The Gardeners' Chronocle July 22, 1899.
THE HYBRIDISATION CONFERENCE
THE arrangements made by the Royal Horticultural Society to collect into a "record" what information had been obtained upon the great subject of Hybridisation were commenced in Chiswick Gardens on Tuesday last, July 11. Dr. Masters, F.R.S., occupied the chair, and the substance of his introductory speech, setting forth the objects the Conference hoped to attain, and extending a welcome to all taking part in the proceedings, whether Britishers or "friends from across the sea," is given in our leading article on p. 50.
The Conference was held in a tent erected near to the Council-room in the Gardens, and the attendance throughout, notwithstanding the great heat, was satisfactory. The programme for the first day was adhered to pretty closely, and below we are able to give summaries of all the papers read.
HYBRIDISATION AND CROSS-BREEDING AS A METHOD OF SCIENTIFIC RESEARCH.
Mr. W. Bateson, M.A., F.R.S., read the first paper, which dealt with "Hybridisation and Crossbreeding as a Method of Scientific Research." It was he with whom the original idea of the Conference started, and he is an example of the broad-minded men that are to be found in the ranks of the zoologists. He said that he had accepted with great pleasure the invitation of the committee to address & gathering of persons interested in the subject. Such an opportunity could not be better used than in pointing out exactly what are the legitimate aims of the methods in question, and what it may be hoped that they will prove. He assumed that the scientific importance of this work lies primarily in its direct bearing on the problem of species.
Though we now believe all forms of life to be connected in descent, yet the fact that they are divided into species is certainly true. The existence of species is a fact that must be faced. How did they arise in evolution?
The two great difficulties besetting all theories of descent are—
Here comes in the work of the breeder, and his experiments are the only ones which can answer these questions. By each work, Mr. Bateson Said, it had already been shown both that variation was often large, and that varieties were discontinuously produced; that such varieties are perpetuated in crossing, and are not, as a matter of fact, obliterated.
This work is to show us which variations are thus discontinuously produced, and which are not; we have speculated long enough on the general theories of evolution; it is better to attack the special case of—How did species A arise from species B.
Taking hairiness and smoothness as typical forms of variation, It was shown that in Matthiola incana, Lychnis vespertina, and Biscutella laevigata, though the relation is in each case a discontinuous one, the mode by which the discontinuity is maintained is different. Plants of these species were produced illustrating the experiments made by Miss E. R. Saunders in Cambridge, from which these results have been obtained. Here the test of cross-breeding revealed at once that variety and type might stand to each other in venous physiological relationships. We talk of "species and varieties" as though the phenomena denoted by these terms are homogeneous. By the test of breeding it is shown that whole sets of distinct phenomena are confused together under these headings. Using the metaphor of chemical science, it is by cross-breeding that the genetic properties of species and varieties must be examined, as the affinities of chemical bodies are.
In this way the confused mass of contradictory properties, which are now attributed to species, may be, unravelled, and we may be delivered from the fruitless debates on this unprofitable subject,
As a practical point Mr. Bateson stated it is by experimental crossing of nearest allies that the work should be begun. It is essential, he continued, that the records should be statistical. Such statistics might at first be rough, but a few notes as to the proportion of offspring, which shows the various characters, are absolutely necessary.
Mr. Bateson in conclusion, emphasised that those who would take part in such work, would earn the gratitude of posterity, and in all probability lay the foundation of a new science t natural history.
Monsieur A. de la Devansaye contributed a paper upon "Fertilisation in the genus Anthurium," in which his previous work upon kindred subjects was briefly alluded to.
[For Aroids, see the Flore des Serres et des Jardins de l'Europe, vol. xxii (1877), p. 37; and for Anthuriums, the succeeding volume, p. 26, as well as the Revue Horticole.]
Two laws already laid down as governing fertilisation and variation in the genus Anthurium were repeated, while a third was added, and strongly emphasised. These are as follows:—
HYBRIDISING AS A MEANS OF PANGENETIC INFECTION.
PROFESSOR DE VRIES explained that Pangenetic infection means the transference of particular qualities from one species to another by means of crossing. Darwin assumed in his Pangenesis that each single peculiarity was represented in the living matter of the cells by a distinct unit. Such unities must, therefore, be capable of isolation and of transmission to allied species.
Many cases in horticultural practice come under this head, but in a scientific way our knowledge on this subject is extremely deficient. Two cases were treated of and illustrated. First were shown twisted stems of Dipsacus sylvestris torsus, the new race with hereditary twisting, raised by Professor de Vries, and of a cross between this race and the ordinary teasel, Dipsacus fullonum, raised by Professor Le Monnier, at Nancy. It was pointed out that the twisting in the two stems of the hybrid, which were demonstrated, was developed to the same high degree as in the seven stems of the parental form, shown for comparison.
In the second place, it was attempted to gain a smooth form of Lychnis diurna by crossing the ordinary hairy form of this species with a newly-detected hairless or glabrous variety of L. vespertina. The hybrids of the first generation were all uniformly hairy, but in the second generation they split up in a multiform mixture, in which the characters of the two parental forms were mixed in all possible combinations. Between these it was easy to find the desired glabrous form, having, in all other respects, the characteristics of a true L. diurna. Such plants were isolated, and fertilised artificially. In the following generation, the new variety proved itself to be fully constant. Of 390 plants, all were glabrous, and of the type of L. diurna. The transfer of the hairlessness, which was the aim of the experiment, was therefore completed in the course of three to four years.
A glabrous variety of Lychnis diurna was found some fifty years ago by Sekera near Mürchengrätz, and described under the name of L. Presli. It was shown to be identical with the hairless hybrid form, an original specimen of Sekera being shown in comparison with living specimens of L. vespertina glabra, and of the new L. diurna glabra.
The result of the experiment was, therefore, to copy the Lychnis Presli, Sekera, which is acknowledged by many writers also as a good species, and which probably originated in the Bohemian Alps from L. diurna by following a totally different way.
HYBRIDISAT1ON AND ITS FAILURES.
Rev. Prof. Henslow remarked that any discussion on hybrids necessitates the preliminary enquiry as to what is a species? It may be defined as being known by a collection of presumably constant characters taken from any or all parts of the plant. Bentham superadded that all the individuals of a species are presumably descended from a common parent. Knight and Herbert, as well as other botanists of their day, found it necessary to introduce the element of hybridisation, for it was thought that if two so-called species produced fertile offspring, they must be really one species, and so, said Herbert, "Botanists must entrench themselves within the genera."
Systematists, however, cannot test the point, and therefore cannot utilize physiological affinities in their diagnoses; the result is, consequently, sometimes unsatisfactory, because the number and kind of characters sufficient to indicate a genus or a species is arbitrary, and when it is reduced to a single feature, though theoretically members of the groups would presumably cross, they are often found not to do so. Thus, both an inferior and a superior ovary are found in the genus Saxifraga and in Begonia; but it is really the sole difference between Liliaceae and Amaryllidaceae, yet no cross exists between any member of these two orders.
Again, Laelia and Cattleya cannot be at all sharply distinguished, unless it be by the single feature of the number of pollen-masses; yet they cross as easily as two varieties of the same species.
Now, Rhododendron, Rhodora, and Azalea are as well differentiated morphologically as any three genera usually are; but they happen to cross, and the question arises: Why are they not still to be regarded as good genera?
To take a particular genus, Herbert found, that some closely, i.e., morphologically allied species of Crinum would not cross, while more distantly allied species—in the opinion of some they should be distinct genera—readily crossed. From this and other experiences, he drew the conclusion that it was really a question of "constitution," as much as of "form." That while the rule holds good that plants which are nearly alike in form are more likely to cross, yet it is not always so. Observing that sub-aquatic species of Crinum failed to cross with more xerophilous species, he thus regarded the failures as due to constitutions induced by external conditions.
Similarly, it frequently happens that groups of species from the same country will readily cross among themselves; but will not ally themselves with other groups of widely separated countries. Thus, the East Indian Rhododendrons refuse to unite with American and Asiatic forms; yet they have produced the "greenhouse" forms in great numbers, with varieties of colours. The same observation holds good sometimes with varieties. Thus, some French strains of Scarlet Pelargoniums, though fertile inter se, fail when crossed with English varieties.
Another cause of failure is excessive prepotency. Taking a normal hybrid as being morphologically intermediate between the two parents, it is now known that either parent may be so excessively prepotent, as not only may the offspring show some considerable inclination towards the parent, but it may practically suppress all features of the other. M. Millardet, in crossing the alpine with the Virginian Strawberries, called them "false hybrids."
Non-reciprocity. This is another puzzling cause of failure; for a cross may sometimes be readily produced one way, but all attempts to raise offspring by crossing the parents in the opposite way may totally fail.
This gives only too frequent and disappointing results. It is due to the fact that the development of the pollen-tube may stimulate the surrounding tissues into growth, without its effecting any impregnation of the ovule itself; so that every external appearance of a successful result may be offered by the enlarged and full-sized fruit; yet there may not be a single seed within containing an embryo.
It has often been found, both by Herbert and later experimenters, that perseverance may be ultimately crowned by success after many disappointments. For the impregnation is so susceptible to external conditions—irrespective of morphological affinities—that a species may fail to be crossed, or to cross another, in one season; but such can be effected in another. Some have even asserted that the time of day may make all the difference between success and failure in certain cases. Or, again, even if progeny be obtained, they may be sterile for years, yet finally bear good seed; hence, an expert has no need to despair, in all cases, when he is anxious to secure some special result, as Nature is as likely as not to reward him for his perseverance. George Henslow.
EXPERIMENTS ON HYBRIDISATION AND CROSS-BREEDING.
Mr. C. C. Hurst, F.L.S., was able in his paper to give a number of conclusions based upon his own observations, and to bring forward evidence, sometimes for, but more often against, generally accepted ideas as to the characters of hybrids.
With regard to inheritance by hybrids among the Orchideae, Mr. Hurst pointed out that what we understand by varietal characters, though of great practical importance, are so indefinable, so uncertain, and so fleeting, as to be traced with difficulty, even in the second generation. Specific features, on the other hand, are more lasting, while generic ones persist but little changed for a number of generations, and would not easily breed out.
As bearing upon the impression that varieties are prepotent, the question was treated in more detail under several headings.
In speaking of generic hybrids, which, as a rule, combine the specific characters of their parents in fairly equal proportions, seven cases were reviewed where the reed-like species of Epidendrum were prepotent in every instance when crossed with species of Cattleya, Laelia, and Sophronitis. Also fifteen others, where more distinct genera, mostly of different tribes, have been crossed together, and in every case have reproduced the seed parent almost exactly, both in generic and specific conformation. The explanation offered was, that this is the result of a kind of parthenogenesis, the pollen probably not having power to fertilise the egg-cells in the ordinary way, but exerting sufficient influence to cause them to start growth.
Primary hybrids, we were told, do not by any means differ so widely from the parent as secondary ones. [Compare Monsieur Devansaye on Anthuriums.] Sex has but little influence per se, and in some recorded cases the resulting offspring from both reverse and obverse cross were practically identical.
Further, in connection with primary crosses, Mr. Hurst exemplified the meaning of his term Partial Prepotency. A certain part of one individual hybrid may show the configuration of one parent; a sister plant may, so far as that is concerned, exemplify the other, while a third hybrid from the same cross may combine in the portion under consideration, the structure of both original species. In colour the exact reverse may be the result. A fraction of the hybrid has alone been considered; repeat the process for all the components of the plant, and the scope for variation, under the circumstances, may easily be understood.
The law of Partial Prepotency is founded by Mr. Hurst, he said, upon practical observations with regard to the genus Paphiopedilum=Cypripedium.
The above remarks, it was pointed out, do not agree with the idea that a hybrid leans first towards one parent and then towards the other, for while it may favour, say, the seed parent in evident characters, in minute details it may reproduce the seed parent. [See Monsieur Morel's remarks upon the Clematis à Ville de Lyon, p. 5.]
Passing on to variation in secondary hybrids, twenty-four individuals of a Paphiopedilum exhibited at the Conference were alluded to. They all came from the same capsule, produced by a hybrid between two species when crossed with a third. The parent hybrid failed to show in its leaves, the special colour of one of its immediate ancestors, but the grandchildren reproduced it strikingly. Statistics were then given that do not support the current opinion as to the absolute sterility of hybrids. Ninety distinct genera, said Mr. Hurst, are recorded in which fertile hybrids have been obtained, and only these where all are practically infertile.
Sterility was a term used by Darwin simply to denote diminished fertility, and this occurs in hybrids undoubtedly, but more owing to diminished power in the males than to anything else. In Paphiopedilum, of crosses made between distinct species 95.05 per cent. were fertile; of hybrids crossed with pure species, 91.82 per cent., while only 60 per cent. of the pure species produced seed when fertilised with pollen from hybrids.
Diminution of fertility in hybrids has already been noted by Darwin, Dr. Focke, Dr. Masters, and Professor Macfarlane in plants, as well as by Professor Ewart in the case of zebra hybrids. It is not, however, confined to hybrids, for it occurs within the limits of a single species; for example, certain races of Primula sinensis raised by Messrs. Sutton & Sons, are difficult to propagate on this account, and Mr. Hurst ascribed diminished fertility rather to conditions of life than to difference in form or constitution brought in through hybridisation.
The stability of hybrids next took up Mr. Hurst's attention, and his statistics did not give the impression that self-fertilised hybrids revert to a parent form when propagated by seed. Out of five hundred seedlings of a hybrid Berberis no less than 90 per cent. reproduced the parent form faithfully and well, and not a single individual reverted wholly to either grandparent.
The increased vigour of hybrids is a well-known fact, and Mr. Hurst puts it down as abnormal growth due to out-crossing the strength of a primary hybrid, he obtained, being reduced to the normal again by in-breeding in the second generation. In discussing the limits of crossing, it was computed that while four species have been combined in Gladiolus, and five in Rhododendrons, no less than twenty-seven genera of Orchideae, many, belonging to different tribes, have been linked together by hybridisation, while possibly there may yet be more.
As a rule for breeders it was held out that success might be hoped for within the limits of a tribe, and, generally, experimenters were exhorted not to be discouraged by even several failures, and recommended, in the interests of science, to keep an accurate record of their work whether successful or otherwise.
SECOND DAY, WEDNESDAY, JULY 12, 1899.
Sir Michael. Foster, K.C.B., Sec. R. S., it was much regretted, being unwell and unfortunately confined to his room, the Rev. Professor Henslow, M.A., V.M.H., very kindly took his place, and presided over the second meeting of the Conference, held on Wednesday afternoon at the Westminster Town Hall. In re-opening the proceedings, Professor Henslow expressed his opinion that there was no necessity for a second address from the chair, and contented himself with making a few brief but pertinent remarks in his usual delightful manner upon the value of the Conference. This, he said, depended in a great measure upon the way in which scientific and practical interests were discussed together. As representing the former side himself, he had to own that botanists did not do all the giving, as they were able to get much valuable information from horticulturists, and, indeed, the two bodies of workers had really to make progress band in hand.
The lantern demonstrations by Mr. Webber, from the U.S. Department of Agriculture, and from Dr. Wilson, of St. Andrew's, were very instructive. After the meeting, a discussion, de omnibus rebus, including copyright in new plants, was indulged in, and proved very acceptable to the auditors.
THE WORK OF THE UNITED STATES DEPARTMENT OF AGRICULTURE IN PLANT HYBRIDISATION.
Mr. Herbert J. Webber, one of the special envoys from the United States department of Agriculture, gave au account of their work which be bears on the question in hand. The department is conducting a series of experiments upon a number of plants, including among others the Orange, Lemon, Pomelo, Pine-apple, Pear and Grape, as well as Wheat, Indian-corn, Cotton, Tomatos, Carnations, Hollyhocks, and Aquilegias.
The speaker discussed the general work which is in progress, and illustrated individual cases of interest by means of lantern-slides. One of the most noteworthy, but at the same time difficult fields of investigation at present pursued, is the production of hardy races of Oranges and Lemons, by hybridising the hardy Citrus trifoliata, which is a deciduous, trifoliate-leaved plant, of very distinct character.
Of forty hybrids of the common Orange ♂, and C. trifoliata ♀, twenty-nine resemble the female-parent almost wholly, while the remaining eleven are clearly intermediate in character. The latter show the effect of the Orange in their increased vigour and larger leaves, with elongated central lobes and laterals, which show a tendency to decrease in size as well as in their evergreen habit. Of fourteen reciprocal hybrids—orange ♀ × C. trifoliata ♂—nine have unifoliate leaves, entirely, resembling the mother-parent; and five have them with three lobes like the male, but with the central one elongated and larger than in the typical trifoliata.
A special point is the complication which arises through the occurrence of polyembryony in Citrus fruits, for besides the embryo developing from the egg-cell proper, which is the only one affected by hybridisation, several other embryos are produced adventitiously from the nucellar tissue of the mother plant.
Seedlings from adventive embryos naturally reproduce the mother parent truly, showing no effects of the hybridisation. A number of photographs was exhibited where several seedlings were seen developing from a single seed, one showing the effect of hybridisation, the others not.
Of 126 hybrids of the Pomelo (Citrus decumana)♀ and Orange (Citrus aurantium)♂, 106 resemble the mother, and, as is almost invariably the case with a few, the rest take after the male-parent. Of 103 reciprocal hybrids, 95 were like the Orange, and 8 like the Pomelo. These experiments were undertaken with the view only of obtaining new valuable varieties.
In other crosses, notably in one where it was sought to unite the loose and easily removable skin of the Mandarin Orange (Citrus nobilis) with the features of the common kind, the same large proportion of plants favoured the seed parent, and a smaller number the pollen parent, which ever way the cross as made.
Experiments to improve the staple of Upland Cotton were also reported upon, and others of which the result is expected to be a tawny cotton similar to the Egyptian kind; which will be suitable for growth in America. It is hoped also to increase the Yield of Indian corn by hybridising the best races commonly grown with distinct varieties, such as the large kerneled Peruvian Corn.
HYBRIDS OF PASSIFLORA, ALBUCA, RIBES, AND BEGONIAS.
DR. J. H. WILSON, F.R.S.E., illustrated some remarks upon hybrids he has obtained, by means of a fine show of lantern slides. Among the Passion-flowers, a cross between Passiflora Buonapartea ♂ × P. coerulea ♀ has been named Margaret Wilson, and was figured in the Gardeners' Chronicle for February 11, 1899. The first-mentioned Passion-flower has a winged quadrangular stem, in the second this is slightly five angled, and the hybrid's stem has the same number of angles, but they are well marked. The flower is structurally a mixture of the two parents from all points of view. The anthers, though well developed, contain but little pollen, and this abnormal. More remarkable is the peculiarity shown by the ovaries: either these contain crumpled, coloured rays, like the coronal ones, or else a miniature ovary, with three styles and stigmas. These structures arise by proliferation of the floral axis at the base of the ovary, but the invaded ovaries are not abnormally enlarged, nor do the ovules seem to be reduced in number. The flowers first produced are most prone to develop the structures above described, while those at the ends of branches have almost always normal ovaries. Assiduous pollination has not yet produced perfect seeds.
A hybrid between P. alba and P. Buonapartea (St. Rule) has three-lobed leaves, like its seed-parent, while the pollen-parent's are ovate In the previous case, where the seed-parent (P. coerulea) had five, or sometimes seven-lobed leaves, the hybrid had invariably three lobes, and if a mean between ovate and three-lobed leaves has been obtained, two-lobed structures might have been Iooked for in the present case. The form has not hitherto produced seed. In the third hybrid between P. Constance Eliott ♀ and P. alba ♂, the leaves are often five-lobed, as in the first, but mixed with the three-lobed form characteristic of the other parent. A fourth cross between P. alba and P. edulis has also resulted in seedlings, but neither these nor the last have yet flowered.
Dr. Wilson briefly alluded to the crosses among eight or nine species of Albuca which he has raised to the number of seventy or more. Details as to their usual intermediate character, and to the prepotency of A. prolifera, so far as its erect white flowers went when crossed with the drooping blossoms of A. minor. Details as to structure in leaves were illustrated by photomicrographs.
Like two or three other experimenters, Dr. Wilson has crossed the Black Currant and Gooseberry, but he has not obtained fertile seed. The pollen of neither parent species takes effect, but a fruit is now ripening as a result of bringing pollen from Ribes divaricatum. An interesting point is, that while the larvae of the Gooseberry-sawfly will not attack Black Currant, it is only too ready to feast on the odourless leaves of the hybrid.
In Begonias, crossing tuberous kinds with Begonia coccinea, many stages intermediate in habit were obtained; some plants retained all their branches, others shed the outer ones by a process similar to leaf fall; while others, again, approached the tuberous condition. A few details with regard to other experiments concluded an interesting contribution.
HYBRIDISATION VIEWED FROM THE STANDPOINT OF SYSTEMATIC BOTANY.
By R. Allen Rolfe, A.L.S., Kew.
The author gave a summary of his paper, commencing with some remarks of Dean Herbert's of the way his early experiments in hybridisation, were received by systematic botanists, who believed that such experiments would tend to confuse their systems. The practice of hybridisation had since made enormous progress, but was still regarded with disfavour by many systematists, who failed to realise how frequently it was carried on in nature, some going so far as to deny that it took place to any considerable extent, if at all, and explaining away the numerous supposed wild hybrids by variation, or mistakes on the part of those who professed to recognise them, whom they described in not very complimentary terms as "hybrid-mongers." By degrees, however, it was being recognised that the views of these individuals were entitled to more respect, for a considerable number of these supposed natural hybrids had been reconstructed artificially, by crossing the supposed parents together. The author then proceeded to enumerate examples of such plants, taken from the genera Epilobium, Narcissus, Tragopogon (raised by Linnaeus himself), Verbascum (quite a series of them), Digitalis, Geum, Salix (at least a dozen), Hieracium, Rubus ("that class of undecided forms in the face of which all the efforts of botanical describers miscarry"), the hybrid Oxlip, two Sarracenias, and a few other plants, beside something like a dozen Orchids, one of which he only recognised at the exhibition on the previous day, though as a wild hybrid it had been known for several years. In Hieracium, particularly, many so-called "new species" had recently been described, both on the Continent and in Britain, which had no right to the title. On the other hand some authors had recognised a number of natural hybrids, combining the characters of others with which they grew, and at least four combinations had been effected between distinct species, one of which did duty in botanical works under no less than eleven spurious specific names. In various other cases what had proved to he one variable hybrid had originally been described not as one, but as several species. In several groups of plants natural hybrids were evidently much more common than was generally admitted, but even sceptics could no longer deny the hybrid origin of those which had been reconstructed artificially. Hybrids certainly broke down the limits between species, sections, and even genera in a few cases, which no doubt accounted for the want of sympathy with which artificially raised ones were regarded by systematists, but the fact must be faced that they also occurred in nature, and could not be ignored. They could not be classified either as species or varieties, and when their true rank was understood many of the difficulties now attending the classification of the latter would vanish. He hoped to see many more experiments undertaken with the view of clearing up the origin of these intermediate and doubtful plants which at present were the bugbear of systematists.
M. Henry de Vilmorin directed attention to two new forms of Poppies, both of which—and particularly the second—he claimed to be plants of real merit or horticultural purposes. In each case Papaver bracteatum was crossed with P. somniferum to begin with; while in the second instance, the hybrid was further crossed with P. orientale, which M. de Vilmorin considers to include P. bracteatum. The special point of interest is that an annual has been crossed successfully with a perennial. A fine series of water colour drawings illustrated M. Vilmorin's remarks.
As one or two contributors of papers were not present in person to read them, there still remained some little time at the disposal of the Conference, which was devoted to a general discussion. The Chairman set the ball rolling by pointing out what a small amount of attention had been paid daring the proceedings to the microscopic structure of hybrids, except by Dr. Wilson. The latter worker, he said, had mentioned Mr. McFarlane's paper on "The Histology of Primary Hybrids," and expressed his opinion that in secondary ones the characters of ancestral species would be much more difficult to trace. Professor Henslow was able to endorse this from his own minute and detailed examination of Messrs. Veitch's greenhouse Rhododendrons, though it must be remembered that they all arose from species presumably nearly allied in structure, and hailing from the same part of the world, With hybrids derived from species of markedly different conformation, such as might depend upon adaptation to a different climate for instance, the task of picking out Specific points which were not found to exist with hybrid Rhododendrons, might be rendered possible. Then Mr. Burbidge brought before the meeting the very great difficulties that had arisen, and do still arise, in systematic work through the Latin names, which have been, and are given, to horticultural hybrids. This speaker was in favour of none but English names being applied; but if the old practice was continued, one should adopt some such plan as combining two generic or specific names, or parts of them, as had been done by Dr. Masters and Sir Michael Foster, and of which the word Laelio-Cattleya was another instance. In come cases it was stated that classical names had been given to hybrids with the express reason, sad to relate, of hiding their real origin. One reason for It, it will be remembered, was hinted at in Dr. Masters' address. The Rev. G. H. Engleheart, M.A., addressed the meeting upon the difficulty of finding the results of others' experience in hybridising, all the records being scattered about, and he suggested that a handbook should be compiled with a view to saving hybridisers much time end trouble. Another point with a practical bearing raised by the same speaker was with regard to the present condition of affairs, where the inventor could protect the results of his brainwork and labour, but anyone rather than the raiser of a new variety obtained the pecuniary reward for the pains taken.
Mr. Geo. Paul, as one commercially interested, spoke upon the same subject, saying that legislation might well be introduced, but Mr. Bunyard, following, showed a way in which a raiser could ensure whatever profit he required by raising sufficient stock before distributing any, and putting a sufficiently high price upon each plant sold. He had often told Mr. Rivers how the latter had given away his varieties, for he (Sir Bunyard) had sometimes, with his facilities and skilled men, raised a bigger stock in a short time than Mr. Rivers himself had in hand.
He pointed out that legislation would be powerless to preserve the rights of the raiser of a new variety or a new plant; prunings might be conscientiously thrown upon the rubbish-heap, but someone else might give them away, and as many plants as there were cuttings struck, or buds inserted, could be reared elsewhere by persons who had not paid for the privilege.
Mr. Willet Hays, of the United States, pointed out how the work of experiment stations might help the producer of a new variety by testing it in various parts of the country, and by proving its adaptability to the region and other advantages, at the same time as it was being made known to growers, and before it was distributed.
Mr. WILLIAM CUTHBERTSON, Rothesay, said he had this summer bloomed Mr. E. J. Lowe's hybrid between an Aquilegia and Clematis Montana. The plant resembled an Aquilegia, but the flower was half saucer-shaped and without spurs. It was bearing seed, and to anyone who wished a few seeds for scientific purposes he would have pleasure in sending them. Some years ago he had tried another of Mr. Lowe's hybrids, one said to be between a Sunflower and a Dahlia, but at the time he was not impressed with it and had not grown it since.
The Chinese Yam (Dioscorea Batatas) has an elongated tuber, penetrating with its bigger end the soil for 3 to 4 feet, and consequently not easily to be dug up. Mons. P. Chappellier, in trying to obtain a variety that should not present this disadvantage to the culturist, made a series of hybridising experiments, of which he furnished an account.
He took principally the species D. Decaisneana, with a spherical tuber as the seed parent, and crossed it with the pollen of the Chinese Yam, without, however, getting very far towards gaining his end, though obtaining some thousands of seedlings.
Most interesting, however, was one individual hybrid he obtained between the two species, for it bore both male and female flowers, these, of course, being restricted to different plants in the parent species; the seeds, however, did not ripen. Another experiment was made in sheer desperation. Mons. Chappellier tried to cross the pigmy D. pyrenaica with D. Batatas, but obtained no result whatever.
Monsieur Chappellier briefly alluded also to a hybrid he had obtained from Mirabilis longiflora ♀, and M. jalapa ♂. This pre-eminently displayed the common characteristics of hybrids to be more vigorous than either parent species, a single plant of the one in question bearing no fewer than four hundred flowers at one time. The plants are also fertile inter se, but such variations arise among the seedlings that it is necessary to propagate them vegetatively. Reprints also of his paper on Recent Hybrids of Crocus sativa (Bul. Soc. Bot. de France, vol. xliv., Feb. 20, 1897), and others bearing upon the question, were sent to the Conference by M. Chappellier.
PROGRESS IN THE UNITED STATES.
PROFESSOR BAILEY, of Cornell University, in his paper on the progress of Hybridisation in the United States of America, gave a bold summary of results rather than an investigation into specific experiments in hybridisation. In judging the question it must be remembered that the standards are different on the two sides of the Atlantic, because the natural and economic conditions are not the same.
In relation to area, intensive gardening is rarer in America than in Europe; there are relatively fewer glass-houses, less interest in individual plants, and less of the amateur's instinct. On the other hand, larger tracts of land are devoted to horticulture. Fruit-growing is more developed than anywhere else in the world, and greater interest is taken in cos. mopolitan varieties.
Again, there is much less interest in hybrids, simply as hybrids. Those hybrids most valued in America are those which fulfil some particular conditions of withstanding sun, or rain, or drought; and it must be remembered that there is as great s diversity of climate in the United States as in the whole of Europe. Hybrid ornamental plants, such as Cannas, Lilies, &c., are quite common over the water, but they are purchased from Europe; and Professor Bailey suggested that we probably should not care for this to be altered.
The hybridising of fruit trees, Vines, Apples, Plums, &c., with native species, was then gone into in some detail, all the work apparently having been undertaken from an economic standpoint, with a view to obtaining plants suitable to special cases. An Apple is wanted to stand the climate of the cold North—Russian races, and Siberian Crab are stocks that have been imported to aid in the pursuit, and so on.
An idea of the magnitude and scope of the work is, that Craig alone made 5000 crosses in Iowa in 1899, and a messenger went 500 miles into Arkansas to obtain pollen to be used at the Experimental Station in the former place.
The European Pear does not thrive in the Southern States, and the introduction of a new specially-raised variety has made profitable Pear-growing possible there.
Attention was also drawn to the Orange experiments brought before the Conference by Mr. Webber. The paper concluded with a list of the chief experimenters, the names of plants dealt with under the heading of particular States, and including Canada.
In his final sentences, Professor Bailey pointed out that by producing a single hybrid which could be named and sold, more immediate results, so far as glory and so on, might be obtained; but when species are blended so that the resulting plants cannot be distinguished from ordinary varieties, them a more useful end is attained.
HYBRIDS IN THE JARDIN DES PLANTES.
MONS. L. HENRY, Curator of the Open-air Department of the Paris Natural History Museum, contributed his notes upon the hybridising experiments, successful or the reverse, to the number of over a hundred, made by himself between the years 1887 and 1899. Perhaps the fullest account which he presented was upon Lilacs, and he sent for exhibition a water-colour drawing of a hybrid and its parents. This was obtained by crossing Syringa Bretschneideri ♀ and S. Josikaea ♂, and the object sought was accomplished, namely, to get darker flowers than those of the seed-parent, while retaining its foliage.
In the converse experiment, S. Bretschneideri ♂ showed its prepotency again, so far as foliage went, the flowers, on the other hand, agreeing with the seed-parent, in colour, form, and size.
M. Henry also made experiments similar to those of M Lemoine, alluded to elsewhere, with a view to clearing up the origin of S. dubia, or Varin's Lilac. By crossing S. vulgaris and S. persica (?S. p. laciniata), he obtained plants identical with Varin's form, so far as foliage went, but unfortunately they died before flowering.
PROPOSED EXPERIMENTS—Monsieur Henry, when alluding to the discovery of the parentage of the Varin's Lilac (Syringa dubia), through the crossing of various species of the genus, took the opportunity of suggesting that the Conference should institute a series of investigations with a view to clearing up the doubtful history of other plants. His first selection of species to be made the subject of hybridising experiments is given below
Mr. CHARLES T. DRUERY, V.M.H., pointed out in his paper on "Fern-crossing and Hybridising," the difficulties arising from the microscopical size of the reproductive organs in Ferns, and their position on the underside of the prothallus. Scientific accuracy as to percentage is one of these, as stray Fern-spores cannot easily be kept out. Florists, he said, can practically make sure that a seed-pod contains A + B, but in Ferns the cross is mainly determined by the resulting combination of characters.
The ordinary process of reproduction in Ferns was entered into in order to emphasise the points alluded to, and then Mr. Druery went on to give details of several planned as well as unintentional crosses which cannot be doubted. Mr. E. J. Lowe's hybrid between Scolopendrium vulgare and Ceterach officinarum is one, and Mr. Druery exhibited fronds of the scaleless Ceterach form with confluent lips and sori infused pairs. P. Schneideri × was next described and brought forward as illustrating the possibilities of endowing exotics allied to our rare British Ferns, with the characteristics of the latter, increasing their beauty, and at the same time rendering them more hardy.
Hints were then given as to facilitating the transit of antherozoids from one prothallus to another in mixed sowings, or where prothalli from separate sowings are subsequently paired, and these were followed by suggestions as to the severance of the sexes by cutting up the prothalli. Crossing in Ferns, continued Mr. Druery, is not limited as in flowers by the necessity of the pollen-tube being of a length agreeing with that of the style, the prothalli being alike except in the case of filmy Ferns, and the size of the Fern proper being quite immaterial. On the other hand it was noticed, in conclusion, that habitual asporogamic reproduction proves an effectual bar to cross-fertilisatlon in many Feins.
A paper was received from M. MOREL on "Hybrids and Mongrels of Clematis," and these may be considered under his various sub-headings.
Clematis coccineo-Pitcheri.—The first experiment in crossing Clematis coccinea ♂ and C. Pitcheri ♀, which belong to the same group, produced a large number of fertile seeds. The seedlings obtained were chiefly interesting from their resemblance inter se, and constituted a form intermediate between the species they were derived from (see E. Andre, Revue Horticole, August, 1893, for a detailed description of the hybrid, as well as for figures of itself and its parents). From C. coccinea it gets its habit of early flowering and its colour, while from C. Pitcheri its vigour, its sepals reflected at their extremities, and its sweet vanilla-like scent. This hybrid seeds copiously and reproduces itself almost exactly, but if pollen from one of the parent species is used, a large number of forms is obtained, that more nearly resemble the pollen parent. Its fertility is adduced as evidence of the near relationship of C. coccinea and C. Pitcheri.
Hybrid No. 378.—This is between C. coccinea male ♂and a large-flowered Clematis as yet unnamed (No. 140) ♀, two species which belong to very different groups. The pollen parent contributes the consistence and a number of sepals. The flower is intermediate in form between the urceolate blossoms of C. coccinea and the spreading ones of No. 140, which latter gives the colour. The leaves are more like that of the former species, and the hybrid has proved sterile up to the present.
Hybrid No. 401.—This hybrid, though having the same pollen parent as the last, and produced also from the seeds of a large-flowered Clematis (Oriflamme), almost completely retains the characters and habits of C. coccinea. The number of its sepals is variable, being sometimes four as in the latter species, sometimes five or six as on the other parent. No. 401 has always proved sterile.
Clematis d Ville de Lyon. —This, which M. Morel considers the most beautiful form of the genus yet obtained, was described and figured in the Revue Horticole of April 16, 1899. The parents are C. coccinea ♂, and a large-flowered form called Viviand Morel, and the appearance of the progeny at first sight seems to belie its origin. The foliage of the hybrid is altogether that of a large-flowered form; the enlarged open flowers in no way recall the sepals of C. coccinea, to which its other hybrids retained some resemblance. The colour of the blossoms, as well as the number, dimensions, and arrangement of the stamens, agree with the pollen. parent, which it also resembles in its constitution, being immune against the attacks of the terrible disease that attacks the large-flowered species of Clematis. M. Morel quoted a parallel case of the hybrid Paeonies between Paeonia officinalis ♀, and P. Rossii ♂, which altogether resemble the seed-parent.
Under the title of "Hybrids of the common and of the laciniated Persian Lilac," Monsieur EMILE LEMOINE pointed out that in approaching the subject of hybridisation, the technical processes must be studied by means of which the work is accomplished. His paper illustrates how the classificatory position and origin of certain plant forms may be cleared up by hybridising trials. Opinions differ as to what the Lilac of Varin really is; whether it be a pure species, a hybrid, or simply a form of Syringa vulgaris.
In endeavouring to obtain a double flowered variety, M. Lemoine persistently tried to cross Varin's Lilac ♀, and the common double form ♂, and vice versa, but without success. A like attempt where the Varin's Lilac was replaced by the typical Persian Lilac, and the white form with similar leaves also failed, but all the flowers of the laciniate Persian Lilac, which has very different foliage from the other, yielded seed when supplied with pollen from the common double Lilac. Some sixty seedlings were obtained; some which have produced single, half-double, and double flowers, and the last, have been named Syringa varina duplex. The conclusions are, that Varin's Lilac is a hybrid, and arose as a chance cross between Syringa vulgaris ♀, and S. persica laciniata male ♂. M. Lemoine's cross, in which S. vulgaris was the pollen-parent, has usually leaves which are smaller than the original Varin form, and sometimes at the base of branches are slightly lobed. The experiments point towards the typical Persian Lilacs also being hybrids.
HYBRID MIMULUS, VIOLA, &C.
Dr. STUART, of Chernside, sent in an account of his hybridising work as an amateur horticulturist. First of all he gave a description of his raising of Mimulus tigrinoides from the garden Mimulus (Scarborough Defiance)♀, and M. cupreus ♂. The plants which proved the dwarfest of this particular section of Mimulus were sent out by Mr. Cannell, of Swanley, and were favourites in their day.
Next, the author alluded to his verification of the steps by which Mr. Grieve obtained his "coloured Pelargoniums." Very weak plants, with highly coloured leaves were produced as a result of crosses either way between Golden Choice and Golden Pheasant. To give vigour of constitution a dwarf, horseshoe-leaved species was used as seed parent, and pollen taken from one of the highly coloured forms.
Among Dr. Stuart's seedlings, obtained from a horse-shoe leaved seed-parent crossed with one of Mr. Grieves' highly-coloured forms, those that had parti-coloured leaves showed most tendency to send out a branch with the characteristic tri-colour markings. When these appeared they were cut off and struck, and the plants so raised kept their character wonderfully. Some plants did not, however, show their true character for years.
Passing on to the question of Tufted Pansies, as he calls the plants commonly alluded to as Violas, Dr. Stuart went into the origin of his well-known hybrids on the genus. Following the idea, started by Mr. Wills, of crossing Viola cornuta from the Pyrenees and the garden Pansy, to increase the hardihood of the cultivated varieties, Dr. Stuart chose "Blue King" as the pollen parent, and was able to raise a dozen hybrid seedlings from Viola cornuta. Their flowers showed the long spur of the mother, but were markedly different from known varieties. The reciprocal cross resulted in straggling plants with Pansy-like flowers, that were of no interest horticulturally speaking. By again crossing the first hybrids with garden Pansies, a number of the large flowered kinds were obtained. Much interesting information was also given by Dr. Stuart with regard to hybrid Aquilegias, Trollii, and Primulas.