Chapter 40

hypothesis of pangenesis.

In the early half of the present chapter I have given a long list of plants in which through bud-variation, that is, independently of reproduction by seed, the fruit has suddenly become modified in size, colour, flavour, hairiness, shape, and time of maturity; flowers have similarly changed in shape, colour, in being double, and greatly in the character of the calyx; young branches or shoots have changed in colour, in bearing spines and in habit of growth, as in climbing or in weeping; leaves have changed in becoming variegated, in shape, period of unfolding, and in their arrangement on the axis. Buds of all kinds, whether produced on ordinary branches or on subterranean stems, whether simple or much modified and supplied with a stock of nutriment, as in tubers and bulbs, are all liable to sudden variations of the same general nature.

In the list, many of the cases are certainly due to reversion to characters not acquired from a cross, but which were formerly present and have since been lost for a longer or shorter time;—as when a bud on a variegated plant produces plain leaves, or when the variously-coloured flowers of the Chrysanthemum revert to the aboriginal yellow tint. Many other cases included in the list are probably due to the plants being of crossed parentage, and to the buds reverting either completely or by segments to one of the two parent-forms.[154]

We may suspect that the strong tendency in the Chrysanthemum to produce by bud-variation differently-coloured flowers, results from the varieties having been at some time intentionally or accidentally crossed; and this is certainly the case with some kinds of Pelargonium. So it may be to a large extent with the bud-varieties of the Dahlia, and with the “broken colours” of Tulips. When, however, a plant reverts by bud-variation to its two parent forms, or to one of them, it sometimes does not revert perfectly, but assumes a somewhat new character,—of which fact, instances have been given, and Carrière gives[155] another in the cherry.

Many cases of bud-variation, however, cannot be attributed to reversion, but to so-called spontaneous variability, as is so common with cultivated plants raised from seed. As a single variety of the Chrysanthemum has produced by buds six other varieties, and as one variety of the gooseberry has borne at the same time four distinct kinds of fruit, it is scarcely possible to believe that all these variations are due to reversion. We can hardly believe, as remarked in a previous chapter, that all the many peaches which have yielded nectarine-buds are of crossed parentage. Lastly, in such cases as that of the moss-rose, with its peculiar calyx, and of the rose which bears opposite leaves, in that of the Imatophyllum, etc., there is no known natural species or variety from which the characters in question could have been derived by a cross. We must attribute all such cases to the appearance of absolutely new characters in the buds. The varieties which have thus arisen cannot be distinguished by any external character from seedlings; this is notoriously the case with the varieties of the Rose, Azalea, and many other plants. It deserves notice that all the plants which have yielded bud-variations have likewise varied greatly by seed.

The plants which have varied by buds belong to so many orders that we may infer that almost every plant would be liable to variation, if placed under the proper exciting conditions. These conditions, as far as we can judge, mainly depend on long-continued and high cultivation; for almost all the plants in the foregoing list are perennials, and have been largely propagated in many soils, under different climates, by cuttings, offsets, bulbs, tubers, and especially by budding or grafting. The instances of annuals varying by buds, or producing on the same plant differently coloured flowers, are comparatively rare: Hopkirk[156] has seen this with _ Convolvulus tricolor_; and it is not uncommon with the Balsam and annual Delphinium. According to Sir R. Schomburgk, plants from the warmer temperate regions, when cultivated under the hot climate of St. Domingo, are eminently liable to bud-variation. I am informed by Mr. Sedgwick that moss-roses which have often been taken to Calcutta always there lose their mossiness; but change of climate is by no means a necessary contingent, as we see with the gooseberry, currant, and in many other cases. Plants living under their natural conditions are very rarely subject to bud-variation. Variegated leaves have, however, been observed under such circumstances; and I have given an instance of variation by buds on an ash-tree planted in ornamental grounds, but it is doubtful whether such a tree can be considered as living under strictly natural conditions. Gärtner has seen white and dark-red flowers produced from the same root of the wild _Achillea millefolium_; and Prof. Caspary has seen a completely wild _ Viola lutea_ bearing flowers of two different colours and sizes.[157]

As wild plants are so rarely liable to bud-variation, whilst highly cultivated plants long propagated by artificial means have yielded many varieties by this form of reproduction, we are led through a series such as the following,—namely, all the eyes in the same tuber of the potato varying in the same manner,—all the fruit on a purple plum-tree suddenly becoming yellow,—all the fruit on a double-flowered almond suddenly becoming peach like,—all the buds on grafted trees being in a very slight degree affected by the stock on which they have been worked,—all the flowers on a transplanted heartsease changing for a time in colour, size, and shape,—we are led by such a series to look at every case of bud-variation as the direct result of the conditions of life to which the plant has been exposed. On the other hand, plants of the same variety may be cultivated in two adjoining beds, apparently under exactly the same conditions, and those in the one bed, as Carrière insists,[158] will produce many bud-variations, and those in the other not a single one. Again, if we look to such cases as that of a peach-tree which, after having been cultivated by tens of thousands during many years in many countries, and after having annually produced millions of buds, all of which have apparently been exposed to precisely the same conditions, yet at last suddenly produces a single bud with its whole character greatly transformed, we are driven to the conclusion that the transformation stands in no _direct_ relation to the conditions of life.

We have seen that varieties produced from seeds and from buds resemble each other so closely in general appearance that they cannot be distinguished. Just as certain species and groups of species, when propagated by seed, are more variable than other species or genera, so it is in the case of certain bud-varieties. Thus, the Queen of England Chrysanthemum has produced by this latter process no less than six, and Rollisson’s Unique Pelargonium four distinct varieties; moss-roses have also produced several other moss-roses. The Rosaceæ have varied by buds more than any other group of plants; but this may be in large part due to so many members having been long cultivated; but within this same group, the peach has often varied by buds, whilst the apple and pear, both grafted trees extensively cultivated, have afforded, as far as I can ascertain, extremely few instances of bud-variation.

The law of analogous variation holds good with varieties produced by buds, as with those produced from seed: more than one kind of rose has sported into a moss-rose; more than one kind of camellia has assumed an hexagonal form; and at least seven or eight varieties of the peach have produced nectarines.

The laws of inheritance seem to be nearly the same with seminal and bud-varieties. We know how commonly reversion comes into play with both, and it may affect the whole, or only segments of a leaf, flower, or fruit. When the tendency to reversion affects many buds on the same tree, it becomes covered with different kinds of leaves, flowers, or fruit; but there is reason to believe that such fluctuating varieties have generally arisen from seed. It is well known that, out of a number of seedling varieties, some transmit their character much more truly by seed than others; so with bud-varieties, some retain their character by successive buds more truly than others; of which instances have been given with two kinds of variegated Euonymus and with certain kinds of tulips and pelargoniums. Notwithstanding the sudden production of bud-varieties, the characters thus acquired are sometimes capable of transmission by seminal reproduction: Mr. Rivers has found that moss-roses generally reproduce themselves by seed; and the mossy character has been transferred by crossing from one species of rose to another. The Boston nectarine, which appeared as a bud-variation, produced by seed a closely allied nectarine. On the other hand, seedlings from some bud-variations have proved variable to an extreme degree.[159] We have also heard, on the authority of Mr. Salter, that seeds taken from a branch with leaves variegated through bud-variation, transmit this character very feebly; whilst many plants, which were variegated as seedlings, transmit variegation to a large proportion of their progeny.

Although I have been able to collect a good many cases of bud-variation, as shown in the previous lists, and might probably, by searching foreign horticultural works, have collected very many more cases, yet their total number is as nothing in comparison with that of seminal varieties. With seedlings raised from the more variable cultivated plants, the variations are almost infinitely numerous, but their differences are generally slight: only at long intervals of time a strongly marked modification appears. On the other hand, it is a singular and inexplicable fact that, when plants vary by buds, the variations, though they occur with comparative rarity, are often, or even generally, strongly pronounced. It struck me that this might perhaps be a delusion, and that slight changes often occurred in buds, but were overlooked or not recorded from being of no value. Accordingly, I applied to two great authorities on this subject, namely, to Mr. Rivers with respect to fruit-trees, and to Mr. Salter with respect to flowers. Mr. Rivers is doubtful, but does not remember having noticed very slight variations in fruit-buds. Mr. Salter informs me that with flowers such do occur, but, if propagated, they generally lose their new character in the following year; yet he concurs with me that bud-variations usually at once assume a decided and permanent character. We can hardly doubt that this is the rule, when we reflect on such cases as that of the peach, which has been so carefully observed, and of which such trifling seminal varieties have been propagated, yet this tree has repeatedly produced by bud-variation nectarines, and only twice (as far as I can learn) any other variety, namely, the Early and Late Grosse Mignonne peaches; and these differ from the parent-tree in hardly any character except the period of maturity.

To my surprise, I hear from Mr. Salter that he brings the principle of selection to bear on variegated plants propagated by buds, and has thus greatly improved and fixed several varieties. He informs me that at first a branch often produces variegated leaves on one side alone, and that the leaves are marked only with an irregular edging or with a few lines of white and yellow. To improve and fix such varieties, he finds it necessary to encourage the buds at the bases of the most distinctly marked leaves, and to propagate from them alone. By following with perseverance this plan during three or four successive seasons, a distinct and fixed variety can generally be secured.

Finally, the facts given in this chapter prove in how close and remarkable a manner the germ of a fertilised seed and the small cellular mass forming a bud, resemble each other in all their functions—in their power of inheritance with occasional reversion,—and in their capacity for variation of the same general nature, in obedience to the same laws. This resemblance, or rather identity of character, is shown in the most striking manner by the fact that the cellular tissue of one species or variety, when budded or grafted on another, may give rise to a bud having an intermediate character. We have seen that variability does not depend on sexual generation, though much more frequently its concomitant than of bud reproduction. We have seen that bud-variability is not solely dependent on reversion or atavism to long-lost characters, or to those formerly acquired from a cross, but appears often to be spontaneous. But when we ask ourselves what is the cause of any particular bud-variation, we are lost in doubt, being driven in some cases to look to the direct action of the external conditions of life as sufficient, and in other cases to feel a profound conviction that these have played a quite subordinate part, of not more importance than the nature of the spark which ignites a mass of combustible matter.

REFERENCES

[1] Since the publication of the first edition of this work, I have found that M. Carrière, _Chef des Pépinières au Mus. d’Hist. Nat.,_ in his excellent Essay ‘Production et Fixation des Variétés, 1865,’ has given a list of bud-variations far more extensive than mine; but as these relate chiefly to cases occurring in France I have left my list as it stood, adding a few facts from M. Carrière and others. Any one who wishes to study the subject fully should refer to M. Carrière’s Essay.

[2] ‘Gardener’s Chronicle,’ 1854, p. 821.

[3] Lindley’s ‘Guide to Orchard,’ as quoted in ‘Gardener’s Chronicle,’ 1852, p. 821. For the _Early mignonne peach, see_ ‘Gardener’s Chronicle,’ 1864, p. 1251.

[4] ‘Transact. Hort. Soc.,’ vol. ii. p. 160.

[5] _See also_ ‘Gardener’s Chronicle,’ 1863, p. 27.

[6] ‘Gardener’s Chronicle,’ 1852, p. 821.

[7] ‘Gardener’s Chronicle,’ 1852, p. 629; 1856, p. 648; 1864, p. 986. Other cases are given by Braun ‘Rejuvenescence,’ in ‘Ray Soc. Bot. Mem.,’ 1853, p. 314.

[8] ‘Ampélographie,’ etc., 1849, p. 71.

[9] ‘Gardener’s Chronicle,’ 1866, p. 970.

[10] ‘Gardener’s Chronicle,’ 1855, pp. 597, 612.

[11] ‘Gardener’s Chronicle,’ 1842, p. 873; 1855, p. 646. In the ‘Chronicle,’ p. 876, Mr. P. Mackenzie states that the bush still continues to bear the three kinds of fruit, “although they have not been every year alike.”

[12] ‘Revue Horticole,’ quoted in ‘Gardener’s Chronicle,’ 1844, p. 87.

[13] ‘Rejuvenescence in Nature,’ ‘Bot. Memoirs Ray Soc.,’ 1853, p. 314.

[14] ‘Comptes Rendus,’ tom. xli. 1855, p. 804. The second case is given on the authority of Gaudichaud, ibid., tom. xxxiv. 1852, p. 748.

[15] This case is given in the ‘Gardener’s Chronicle,’ 1867, p. 403.

[16] ‘Journal of Proc. Linn. Soc.,’ vol ii. Botany, p. 131.

[17] ‘Gardener’s Chronicle,’ 1847, p. 207.

[18] Herbert, ‘Amaryllidaceæ,’ 1838, p. 369.

[19] ‘Gardener’s Chronicle,’ 1843, p. 391.

[20] Exhibited at Hort. Soc. London. Report in ‘Gardener’s Chronicle,’ 1844, p. 337.

[21] Mr. W. Bell ‘Bot. Soc. of Edinburgh,’ May, 1863.

[22] ‘Revue Horticole,’ quoted in ‘Gardener’s Chronicle,’ 1845, p. 475.

[23] ‘Bastarderzeugung,’ 1849, s. 76.

[24] ‘Journal of Horticulture,’ 1861, p. 336.

[25] W. P. Ayres, in ‘Gardener’s Chronicle,’ 1842, p. 791.

[26] W. P. Ayres, ibid.

[27] Dr. Maxwell Masters, ‘Pop. Science Review,’ July, 1872, p. 250.

[28] ‘Gardener’s Chronicle,’ 1861, p. 968.

[29] Ibid., 1861 p. 945.

[30] W. Paul, in ‘Gardener’s Chronicle,’ 1861, p. 968.

[31] Ibid., p. 945.

[32] For other cases of bud-variation in this same variety, _ see_ ‘Gardener’s Chronicle,’ 1861, pp. 578, 600, 925. For other distinct cases of bud-variation in the genus Pelargonium _see_ ‘Cottage Gardener,’ 1860, p. 194.

[33] Dr. Maxwell Masters, ‘Pop. Science Review,’ July, 1872, p. 254.

[34] Rev. W. T. Bree, in Loudon’s ‘Gardener’s Mag.,’ vol. viii. 1832, p. 93.

[35] ‘The Chrysanthemum: its History and Culture,’ by J. Salter, 1865, p. 41, etc.

[36] Bree, in Loudon’s ‘Gardener’s Mag.,’ vol. viii. 1832, p. 93.

[37] Bronn ‘Geschichte der Natur,’ B. ii. s. 123.

[38] T. Rivers, ‘Rose Amateur’s Guide ‘ 1837 p. 4.

[39] Mr. Shailer, quoted in ‘Gardener’s Chronicle,’ 1848 p. 759.

[40] ‘Transact. Hort. Soc.,’ vol. iv. 1822, p. 137; ‘Gardener’s Chronicle,’ 1842, p. 422.

[41] _See also_ Loudon’s ‘Arboretum,’ vol. ii. p. 780.

[42] All these statements on the origin of the several varieties of the moss-rose are given on the authority of Mr. Shailer, who, together with his father, was concerned in their original propagation. _See_ ‘Gardener’s Chronicle,’ 1852, p. 759.

[43] ‘Gardener’s Chronicle,’ 1845, p. 564.

[44] ‘Transact. Hort. Soc.,’ vol. ii. p. 242.

[45] ‘Shriften der Phys. Oekon. Gesell. zu Königsberg,’ Feb. 3rd, 1865, s. 4. _See also_ Dr. Caspary’s paper in ‘Transactions of the Hort. Congress of Amsterdam,’ 1865.

[46] ‘Gardener’s Chronicle,’ 1852, p. 759.

[47] ‘Transact. Hort. Soc.,’ vol. ii. p. 242.

[48] Sir R. Schomburgk, ‘Proc. Linn. Soc. Bot.,’ vol. ii. p. 132.

[49] ‘Gardener’s Chronicle,’ 1862, p. 619.

[50] Hopkirk’s ‘Flora Anomala,’ 167.

[51] ‘Sur La Production et la Fixation des Variétés,’ 1865, p. 4.

[52] ‘Journal of Horticulture,’ March, 1865, p. 233.

[53] ‘Gardener’s Chronicle,’ 1843, p. 135.

[54] Ibid., 1842, p. 55.

[55] ‘Gardener’s Chronicle,’ 1867, p. 235.

[56] Gärtner ‘Bastarderzeugung,’ s. 305.

[57] Mr. D. Beaton, in ‘Cottage Gardener,’ 1860, p. 250.

[58] ‘Gardener’s Chronicle,’ 1850, p. 536.

[59] Braun, ‘Ray Soc. Bot. Mem.,’ 1853, p. 315; Hopkirk’s ‘Flora Anomala,’ p. 164; Lecoq ‘Géograph. Bot. de l’Europe,’ tom. iii. 1854, p. 405; and ‘De la Fécondation,’ 1862, p. 303.

[60] ‘Des Variétés,’ 1865, p. 5.

[61] W. Mason, in ‘Gardener’s Chronicle,’ 1843, p. 878.

[62] Alex. Braun, ‘Ray Soc. Bot. Mem.,’ 1853, p. 315; ‘Gardener’s Chronicle,’ 1841, p. 329.

[63] Dr. M. T. Masters, ‘Royal Institution Lecture,’ March 16th, 1860.

[64] _See_ Mr. W. K. Bridgeman’s curious paper in ‘Annals and Mag. of Nat. Hist.,’ Dec. 1861; also Mr. J. Scott, ‘Bot. Soc. Edinburgh,’ June 12th, 1862.

[65] ‘Journal of Horticulture,’ 1861, p. 336; Verlot, ‘Des Variétés,’ p. 76.

[66] _See also_ Verlot, ‘Des Variétés,’ p. 74.

[67] ‘Gardener’s Chronicle,’ 1844, p. 86.

[68] Ibid., 1861, p. 963.

[69] Ibid., 1861, p. 433; ‘Cottage Gardener,’ 1860, p. 2.

[70] M. Lemoine (quoted in ‘Gardener’s Chronicle,’ 1867, p. 74) has lately observed that the Symphytum with variegated leaves cannot be propagated by division of the roots. He also found that out of 500 plants of a Phlox with striped flowers, which had been propagated by root-division, only seven or eight produced striped flowers. _See also_ on striped Pelargoniums, ‘Gardener’s Chronicle,’ 1867, p. 1000.

[71] Anderson’s ‘Recreations in Agriculture,’ vol. v. p. 152.

[72] For wheat, _see_ ‘Improvement of the Cereals,’ by P. Shirreff, 1873, p. 47. For maize and sugar-cane, Carrière, ibid., pp. 40, 42. With respect to the sugar-cane Mr. J. Caldwell of Mauritius, says (‘Gardener’s Chronicle,’ 1874, p. 316) the Ribbon cane has here “sported into a perfectly green cane and a perfectly red cane from the same head. I verified this myself, and saw at least 200 instances in the same plantation, and the fact has completely upset all our preconceived ideas of the difference of colour being permanent. The conversion of a striped cane into a green cane was not uncommon, but the change into a red cane universally disbelieved, and that both events should occur in the same plant incredible. I find, however, in Fleischman’s ‘Report on Sugar Cultivation in Louisiana for 1848,’ by the American Patent Office, the circumstance is mentioned, but he says he never saw it himself.”

[73] ‘Gardener’s Chronicle,’ 1857, p. 662.

[74] ‘Gardener’s Chronicle,’ 1841, p. 814.

[75] Ibid., 1857, p. 613.

[76] Ibid., 1857, p. 679. _See also_ Philips ‘Hist. of Vegetables,’ vol. ii. p. 91, for other and similar accounts.)

[77] ‘Journal of Proc. Linn. Soc.,’ vol. ii. Botany, p. 132.

[78] Loudon’s ‘Gardener’s Mag.,’ vol. viii. 1832, p. 94.

[79] ‘Gardener’s Chronicle,’ 1850, p. 536; and 1842, p. 729.

[80] ‘Des Jacinthes,’ etc., Amsterdam, 1768, p. 122.

[81] ‘Gardener’s Chronicle.’ 1845. p. 212.

[82] Loudon’s ‘Encyclopædia of Gardening,’ p. 1024.

[83] ‘Production des Variétés,’ 1865, p. 63.

[84] ‘Gardener’s Chronicle,’ 1841, p. 782; 1842, p. 55.

[85] ‘Gardener’s Chronicle,’ 1849. p. 565.

[86] ‘Transact. Lin. Soc.,’ vol. ii. p. 354.

[87] Godron, ‘De l’Espèce,’ tom. ii. p. 84.

[88] M. Carrière has lately described in the ‘Revue Horticole,’ (Dec. 1st, 1866, p. 457,) an extraordinary case. He twice inserted grafts of the _Aria vestita_ on thorn-trees (_épines_) growing in pots; and the grafts, as they grew, produced shoots with bark, buds, leaves, petioles, petals, and flower-stalks, all widely different from those of the Aria. The grafted shoots were also much hardier, and flowered earlier, than those on the ungrafted Aria.

[89] ‘Transact. Hort. Soc.,’ vol. ii. p. 160.

[90] For the cases of oaks _see_ Alph. De Candolle in ‘Bibl. Univers.,’ Geneva, Nov. 1862; for limes, etc., Loudon’s ‘Gard. Mag.,’ vol. xi. 1835, p. 503.

[91] For analogous facts, _see_ Braun ‘Rejuvenescence,’ in ‘Ray Soc. Bot. Mem.,’ 1853, p. 320; and ‘Gardener’s Chronicle,’ 1842, p. 397; also Braun in ‘Sitzungsberichte der Ges. naturforschender Freunde,’ June, 1873, p. 63.

[92] ‘Journal of Hort. Soc.,’ vol. ii. 1847, p. 100.

[93] _See_ ‘Transact. of Hort. Congress of Amsterdam,’ 1865; but I owe most of the following information to Prof. Caspary’s letters.

[94] ‘Nouvelles Archives du Muséum,’ tom. i. p. 143.

[95] _See_ on this head, Naudin, ibid., p. 141.

[96] Braun, in ‘Bot. Mem. Ray. Soc.,’ 1853, p. 23.

[97] This hybrid has never been described. It is exactly intermediate in foliage, time of flowering, dark striæ at the base of the standard petal, hairiness of the ovarium, and in almost every other character, between _C. laburnum_ and _ alpinus_; but it approaches the former species more nearly in colour, and exceeds it in the length of the racemes. We have before seen that 20·3 per cent of its pollen-grains are ill-formed and worthless. My plant, though growing not above thirty or forty yards from both parent-species, during some seasons yielded no good seeds; but in 1866 it was unusually fertile, and its long racemes produced from one to occasionally even four pods. Many of the pods contained no good seeds, but generally they contained a single apparently good seed, sometimes two, and in one case three seeds. Some of these seeds germinated, and I raised two trees from them; one resembles the present form; the other has a remarkable dwarf character with small leaves, but has not yet flowered.

[98] ‘Annales de la Soc. de l’Hort. de Paris,’ tom. vii. 1830, p. 93.

[99] An account was given in the ‘Gardener’s Chronicle’ (1857, pp. 382, 400) of a common laburnum on which grafts of _C. purpureus_ had been inserted, and which gradually assumed the character of _C. adami_; but I have little doubt that _C. adami_ had been sold to the purchaser, who was not a botanist, in the place of _C. purpureus._ I have ascertained that this occurred in another instance.

[100] Gallesio, ‘Gli Agrumi dei Giard. Bot. Agrar. di. Firenze,’ 1839, p. 11. In his ‘Traité du Citrus,’ 1811, p. 146, he speaks as if the compound fruit consisted in part of a lemon, but this apparently was a mistake.

[101] ‘Gardener’s Chronicle,’ 1855, p. 628. _See also_ Prof. Caspary in ‘Transact. Hort. Congress of Amsterdam,’ 1865.

[102] Gärtner (‘Bastarderzeugung,’ s. 611) gives many references on this subject.

[103] A nearly similar account was given by Brabley, in 1724, in his ‘Treatise on Husbandry,’ vol. i. p. 199.

[104] Morren, ‘Bull. de l’Acad. R. des Sciences de Belgique,’ 2de séries, tom. xxviii. 1869, p. 434. Also Magnus ‘Gesellschaft naturforschender Freunde, Berlin,’ Feb. 21st, 1871, p. 13; ibid., June 21st, 1870, and Oct. 17th, 1871. Also ‘Bot. Zeitung,’ Feb. 24th, 1871.

[105] Loudon’s ‘Arboretum,’ vol. iv. p. 2595.

[106] ‘Bastarderzeugung,’ s. 619.

[107] Amsterdam, 1768, p. 124.

[108] ‘Gardener’s Chronicle,’ 1860, p. 672, with a woodcut.

[109] _See_ ‘Gardener’s Chronicle,’ 1869, p. 220.

[110] ‘Gardener’s Chronicle,’ 1869, p. 335.

[111] ‘Gardener’s Chronicle,’ 1869, p. 1018, with remarks by Dr. Masters on the adhesion of the united wedges. _See also_ ibid., 1870, pp. 1277, 1283.

[112] ‘Gardener’s Chronicle,’ 1871, p. 837.

[113] ‘Gardener’s Chronicle,’ 1870, p. 1506.

[114] ‘Sitzungsberichte der Gesellschaft naturforschender Freunde zu Berlin,’ Oct. 17th, 1871.

[115] Ibid., Nov. 17th, 1874. _See also_ excellent remarks by Herr Magnus.

[116] ‘Bastarderzeugung,’ s. 549. It is, however, doubtful whether these plants should be ranked as species or varieties.

[117] Gärtner, ibid., s. 550.

[118] ‘Journal de Physique,’ tom. xxiii. 1873, p. 100. ‘Act. Acad. St. Petersburgh,’ 1781, part i. p. 249.

[119] ‘Nouvelles Archives du Muséum,’ tom. i. p. 49.

[120] L’Hermès, Jan. 14th, 1837, quoted in Loudon’s ‘Gardener’s Mag.,’ vol. xiii. p. 230.

[121] ‘Comptes Rendus,’ tom. xxxiv. 1852, p. 746.

[122] ‘Géograph. Bot. de l’Europe,’ tom. iii. 1854, p. 405; and ‘De la Fécondation,’ 1862, p. 302.

[123] ‘Traité du Citrus,’ 1811, p. 45.

[124] ‘Transact. Linn. Soc.,’ vol. ix. p. 268.

[125] ‘Annals and Mag. of Nat. Hist.,’ March, 1848.

[126] ‘Pomologie Physiolog.,’ 1830, p. 126.

[127] ‘Philosophical Transact.,’ vol. xliii. 1744-45, p. 525.

[128] Mr. Goss, ‘Transact. Hort. Soc.,’ vol. v. p. 234: and Gärtner, ‘Bastarderzeugung,’ 1849, ss. 81 and 499.

[129] ‘Gardener’s Chronicle,’ 1854, p. 404.

[130] Ibid., 1866, p. 900.

[131] _See also_ a paper by this observer read before the International Hort. and Bot. Congress of London, 1866.

[132] ‘Traité du Citrus,’ p. 40.

[133] ‘Transact. Hort. Soc.,’ vol. iii. p. 318. _See also_ vol. v. p. 65.

[134] Prof. Asa Gray, ‘Proc. Acad. Sc.,’ Boston, vol. iv. 1860, p. 21. I have received statements to the same effect from other persons in the United States.

[135] For the French case _see_ ‘Journ. Hort. Soc.,’ vol. i. new series, 1866, p. 50. For Germany, _see_ M. Jack quoted in Henfrey’s ‘Botanical Gazette,’ vol. i. p. 277. A case in England has recently been alluded to by the Rev. J. M. Berkeley before the Hort. Soc. of London.

[136] ‘Philosophical Transactions,’ vol. xlvii. 1751-52, p. 206.

[137] Gallesio, ‘Teoria della Riproduzione,’ 1816, p. 95.

[138] ‘Bot. Zeitung,’ May, 1868, p. 326.

[139] _See_ Dr. J. Stockton-Hough, in ‘American Naturalist,’ Jan. 1874, p. 29.

[140] ‘Transact. Hort. Soc.,’ vol. v. p. 69.

[141] ‘Bull. de l’Acad. Imp. de St. Petersburg,’ tom. xvii. p. 275, 1872. The author gives references to those cases in the Solanaceæ of fruit affected by foreign pollen, but as it does not appear that the mother-plant was artificially fertilised, I have not entered into details.

[142] ‘Bot. Zeitung,’ Sept. 1868, p. 631. For Maximowicz’s judgment, _see_ the paper last referred to.

[143] ‘Journal of Horticulture,’ Jan. 20th, 1863, p. 46.

[144] _See_ on this head the high authority of Prof. Decaisne, in a paper translated in ‘Journ. Hort. Soc.,’ vol. i., new series, 1866, p. 48.

[145] Vol. xliii., 1744-45, p. 525; vol. xlv., 1747-48, p. 602.

[146] ‘Transact. Hort. Soc.,’ vol. v. pp. 65 and 68. _See also_ Prof. Hildebrand, with a coloured figure, in ‘Bot. Zeitung,’ May 15th, 1868, p. 327. Puvis also has collected, ‘De La Dégénération,’ 1837, p. 36)several other instances; but it is not in all cases possible to distinguish between the direct action of foreign pollen and bud-variations.

[147] T. de Clermont-Tonnerre, in ‘Mém. de la Soc. Linn. de Paris,’ tom. iii. 1825, p. 164.

[148] ‘Transact. of Hort. Soc.,’ vol. v. p. 68.

[149] ‘Beiträge zur Kenntniss der Befruchtung,’ 1844, s. 347-351.

[150] ‘Die Fruchtbildung der Orchideen, ein Beweis für die doppelte Wirkung des Pollens,’ ‘Botanische Zeitung,’ No. 44 et seq., Oct. 30th, 1865; and Aug. 4th, 1865, s. 249.

[151] ‘Philos. Transact.,’ 1821, p. 20.

[152] Dr. Alex. Harvey on ‘A remarkable Effect of Cross-breeding,’ 1851. On the ‘Physiology of Breeding,’ by Mr. Reginald Orton, 1855. ‘Intermarriage,’ by Alex. Walker, 1837. ‘L’Hérédité Naturelle,’ by Dr. Prosper Lucas, tom. ii. p. 58. Mr. W. Sedgwick, in ‘British and Foreign Medico-Chirurgical Review,’ 1863, July, p. 183. Bronn, in his ‘Geschichte der Natur,’ 1843, B. ii. s. 127, has collected several cases with respect to mares, sows, and dogs. Mr. W. C. L. Martin (‘History of the Dog,’ 1845, p. 104) says he can personally vouch for the influence of the male parent on subsequent litters by other dogs. A French poet, Jacques Savary, who wrote in 1665 on dogs, was aware of this singular fact. Dr. Bowerbank has given us the following striking case:—A black, hairless Barbary bitch was first accidentally impregnated by a mongrel spaniel with long brown hair, and she produced five puppies, three of which were hairless and two covered with _ short_ brown hair. The next time she was put to a black, hairless Barbary dog; “but the mischief had been implanted in the mother, and again about half the litter looked like pure Barbarys, and the other half like the _short_-haired progeny of the first father.” I have given in the text one case with pigs; an equally striking one has been recently published in Germany, ‘Illust. Landwirth. Zeitung,’ 1868, Nov. 17th, p. 143. It is worth notice that farmers in S. Brazil (as I hear from Fritz Müller), and at the C. of Good Hope (as I have heard from two trustworthy persons) are convinced that mares which have once borne mules, when subsequently put to horses, are extremely liable to produce colts, striped like a mule. Dr. Wilckens, of Pogarth, gives (‘Jahrbuch Landwirthschaft,’ ii. 1869, p. 325) a striking and analogous case. A merino ram, having two small lappets or flaps of skin on the neck, was in the winter of 1861-62 put to several Merino ewes, all of whom bore lambs with similar flaps on their necks. The ram was killed in the spring of 1862 and subsequently to his death the ewes were put to other Merino rams, and in 1863 to Southdown rams, none of whom ever have neck lappets: nevertheless, even as long afterwards as 1867, several of these ewes produced lambs bearing these appendages.

[153] ‘Le Pigeon Voyageur Belge,’ 1865, p. 59.

[154] It may be worth while to call attention to the several means by which flowers and fruit become striped or mottled. Firstly, by the direct action of the pollen of another variety or species, as in the cases given of oranges and maize. Secondly, in crosses of the first generation, when the colours of the two parents do not readily unite, as with Mirabilis and Dianthus. Thirdly, in crossed plants of a subsequent generation by reversion, through either bud or seminal generation. Fourthly, by reversion to a character not originally gained by a cross, but which had long been lost, as with white-flowered varieties, which we shall hereafter see often become striped with some other colour. Lastly, there are cases, as when peaches are produced with a half or quarter of the fruit like a nectarine, in which the change is apparently due to mere variation, through either bud or seminal generation.

[155] ‘Production des Variétés,’ p. 37.

[156] ‘Flora Anomala,’ p. 164.

[157] ‘Schriften der physisch-okon. Gesell. zu Königsberg,’ B. vi. Feb. 3rd, 1865, s. 4.

[158] ‘Production des Variétés,’ pp. 58, 70.

[159] Carrière, ‘Production des Variétés,’ p. 39.