Sterility from the excessive development of the organs of Growth or Vegetation.—Plants which from any cause grow too luxuriantly, and produce leaves, stems, runners, suckers, tubers, bulbs, etc., in excess, sometimes do not flower, or if they flower do not yield seed. To make European vegetables under the hot climate of India yield seed, it is necessary to check their growth; and, when one-third grown, they are taken up, and their stems and tap-roots are cut or mutilated.[105] So it is with hybrids; for instance, Prof. Lecoq[106] had three plants of Mirabilis, which, though they grew luxuriantly and flowered, were quite sterile; but after beating one with a stick until a few branches alone were left, these at once yielded good seed. The sugar-cane, which grows vigorously and produces a large supply of succulent stems, never, according to various observers, bears seed in the West Indies, Malaga, India, Cochin China, Mauritius, or the Malay Archipelago.[107] Plants which produce a large number of tubers are apt to be sterile, as occurs, to a certain extent, with the common potato; and Mr. Fortune informs me that the sweet potato (Convolvulus batatas) in China never, as far as he has seen, yields seed. Dr. Royle remarks[108] that in India the Agave vivipara, when grown in rich soil, invariably produces bulbs, but no seeds; whilst a poor soil and dry climate lead to an opposite result. In China, according to Mr. Fortune, an extraordinary number of little bulbs are developed in the axils of the leaves of the yam, and this plant does not bear seed. Whether in these cases, as in those of double flowers and seedless fruit, sexual sterility from changed conditions of life is the primary cause which leads to the excessive development of the organs of vegetation, is doubtful; though some evidence might be advanced in favour of this view. It is perhaps a more probable view that plants which propagate themselves largely by one method, namely by buds, have not sufficient vital power or organised matter for the other method of sexual generation.
Several distinguished botanists and good practical judges believe that long- continued propagation by cuttings, runners, tubers, bulbs, etc., independently of any excessive development of these parts, is the cause of many plants failing to produce flowers, or producing only barren flowers,—it is as if they had lost the habit of sexual generation.[109] That many plants when thus propagated are sterile there can be no doubt, but as to whether the long continuance of this form of propagation is the actual cause of their sterility, I will not venture, from the want of sufficient evidence, to express an opinion.
That plants may be propagated for long periods by buds, without the aid of sexual generation, we may safely infer from this being the case with many plants which must have long survived in a state of nature. As I have had occasion before to allude to this subject, I will here give such cases as I have collected. Many alpine plants ascend mountains beyond the height at which they can produce seed.[110] Certain species of Poa and Festuca, when growing on mountain-pastures, propagate themselves, as I hear from Mr. Bentham, almost exclusively by bulblets. Kalm gives a more curious instance[111] of several American trees, which grow so plentifully in marshes or in thick woods, that they are certainly well adapted for these stations, yet scarcely ever produce seeds; but when accidentally growing on the outside of the marsh or wood, are loaded with seed. The common ivy is found in Northern Sweden and Russia, but flowers and fruits only in the southern provinces. The Acorus calamus extends over a large portion of the globe, but so rarely perfects fruit that this has been seen only by a few botanists; according to Caspary, all its pollen-grains are in a worthless condition.[112] The Hypericum calycinum, which propagates itself so freely in our shrubberies by rhizomes, and is naturalised in Ireland, blossoms profusely, but rarely sets any seed, and this only during certain years; nor did it set any when fertilised in my garden by pollen from plants growing at a distance. The Lysimachia nummularia, which is furnished with long runners, so seldom produces seed-capsules, that Prof. Decaisne,[113] who has especially attended to this plant, has never seen it in fruit. The Carex rigida often fails to perfect its seed in Scotland, Lapland, Greenland, Germany, and New Hampshire in the United States.[114] The periwinkle (Vinca minor), which spreads largely by runners, is said scarcely ever to produce fruit in England;[115] but this plant requires insect-aid for its fertilisation, and the proper insects may be absent or rare. The Jussiaea grandiflora has become naturalised in Southern France, and has spread by its rhizomes so extensively as to impede the navigation of the waters, but never produces fertile seed.[116] The horse-radish (Cochleria armoracia) spreads pertinaciously and is naturalised in various parts of Europe; though it bears flowers, these rarely produce capsules: Professor Caspary informs me that he has watched this plant since 1851, but has never seen its fruit; 65 per cent of its pollen-grains are bad. The common Ranunculus ficaria rarely bears seed in England, France, or Switzerland; but in 1863 I observed seeds on several plants growing near my house.[117] Other cases analogous with the foregoing could be given; for instance, some kinds of mosses and lichens have never been seen to fructify in France.
Some of these endemic and naturalised plants are probably rendered sterile from excessive multiplication by buds, and their consequent incapacity to produce and nourish seed. But the sterility of others more probably depends on the peculiar conditions under which they live, as in the case of the ivy in the northern part of Europe, and of the trees in the swamps of the United States; yet these plants must be in some respects eminently well adapted for the stations which they occupy, for they hold their places against a host of competitors.
Finally, the high degree of sterility which often accompanies the doubling of flowers, or an excessive development of fruit, seldom supervenes at once. An incipient tendency is observed, and continued selection completes the result. The view which seems the most probable, and which connects together all the foregoing facts and brings them within our present subject, is, that changed and unnatural conditions of life first give a tendency to sterility; and in consequence of this, the organs of reproduction being no longer able fully to perform their proper functions, a supply of organised matter, not required for the development of the seed, flows either into these organs and renders them foliaceous, or into the fruit, stems, tubers, etc., increasing their size and succulency. But it is probable that there exists, independently of any incipient sterility, an antagonism between the two forms of reproduction, namely, by seed and buds, when either is carried to an extreme degree. That incipient sterility plays an important part in the doubling of flowers, and in the other cases just specified, I infer chiefly from the following facts. When fertility is lost from a wholly different cause, namely, from hybridism, there is a strong tendency, as Gärtner[118] affirms, for flowers to become double, and this tendency is inherited. Moreover, it is notorious that with hybrids the male organs become sterile before the female organs, and with double flowers the stamens first become foliaceous. This latter fact is well shown by the male flowers of dioecious plants, which, according to Gallesio[119] first become double. Again, Gärtner[120] often insists that the flowers of even utterly sterile hybrids, which do not produce any seed, generally yield perfect capsules or fruit,—a fact which has likewise been repeatedly observed by Naudin with the Cucurbitaceæ; so that the production of fruit by plants rendered sterile through any cause is intelligible. Kölreuter has also expressed his unbounded astonishment at the size and development of the tubers in certain hybrids; and all experimentalists[121] have remarked on the strong tendency in hybrids to increase by roots, runners, and suckers. Seeing that hybrid plants, which from their nature are more or less sterile, thus tend to produce double flowers; that they have the parts including the seed, that is the fruit, perfectly developed, even when containing no seed; that they sometimes yield gigantic roots; that they almost invariably tend to increase largely by suckers and other such means;—seeing this, and knowing, from the many facts given in the earlier parts of this chapter, that almost all organic beings when exposed to unnatural conditions tend to become more or less sterile, it seems much the most probable view that with cultivated plants sterility is the exciting cause, and double flowers, rich seedless fruit, and in some cases largely-developed organs of vegetation, etc., are the indirect results—these results having been in most cases largely increased through continued selection by man.
REFERENCES
[1] For England, see below. For Germany, see Metzger, ‘Getreidearten,’ 1841, s. 63. For France, Loiseleur-Deslongchamps (‘Consid. sur les Céréales,’ 1843, p. 200) gives numerous references on this subject. For Southern France, see Godron, ‘Florula Juvenalis,’ 1854, p. 28.
[2] ‘A General Treatise of Husbandry,’ vol. 3 p. 58.
[3] ‘Gardener’s Chronicle and Agricult. Gazette,’ 1858, p. 247; and for the second statement, Ibid., 1850, p. 702. On this same subject see also Rev. D. Walker’s ‘Prize Essay of Highland Agricult. Soc.’ vol. ii. p. 200. Also Marshall ‘Minutes of Agriculture,’ November, 1775.
[4] Oberlin’s ‘Memoirs,’ Eng. translat., p. 73. For Lancashire see Marshall’s ‘Review of Reports,’ 1808, p. 295.
[5] ‘Cottage Gardener,’ 1856, p. 186. For Mr. Robson’s subsequent statements, see ‘Journal of Horticulture,’ Feb. 18, 1866, p. 121. For Mr. Abbey’s remarks on grafting, etc., Ibid., July 18, 1865, p. 44.
[6] ‘Mém. de l’Acad. des Sciences,’ 1790, p. 209.
[7] ‘On the Varieties of Wheat,’ p. 52.
[8] Mr. Spencer has fully and ably discussed this whole subject in his ‘Principles of Biology,’ 1864, vol. ii. ch. x. In the first edition of my ‘Origin of Species,’ 1859, p. 267, I spoke of the good effects from slight changes in the conditions of life and from cross-breeding, and of the evil effects from great changes in the conditions and from crossing widely distinct forms, as a series of facts “connected together by some common but unknown bond, which is essentially related to the principle of life.”
[9] ‘Essais de Zoologie Générale,’ 1841, p. 256.
[10] Since the appearance of the first edition of this work, Mr. Sclater has published (‘Proc. Zoolog. Soc.,’ 1868, p. 623) a list of the species of mammals which have bred in the gardens from 1848 to 1867 inclusive. Of the Artiodactyla 85 species have been kept, and of these 1 species in 1·9 have bred at least once during the 20 years; of 28 Marsupialia, 1 in 2·5 have bred; of 74 Carnivora, 1 in 3·0 have bred; of 52 Rodentia, 1 in 4·7 have bred; and of Quadrumana 75 species have been kept, and 1 in 6·2 have bred.
[11] Du Rut, ‘Annales du Muséum,’ 1807, tom. ix. p. 120.
[12] ‘Saugethiere von Paraguay,’ 1830, s. 49, 106, 118, 124, 201, 208, 249, 265, 327.
[13] ‘The Naturalist on the Amazons,’ 1863, vol. i. pp. 99, 193; vol. ii. p. 113.
[14] ‘Embassy to the Court of Ava,’ vol. i. p. 534.
[15] ‘Journal,’ vol. i. p. 213.
[16] ‘Säugethiere,’ s. 327.
[17] On the Breeding of the Larger Felidæ, ‘Proc. Zoolog. Soc.,’ 1861, p. 140.
[18] Sleeman’s ‘Rambles in India,’ vol. ii. p. 10.
[19] Wiegmann’s ‘Archiv. fur Naturgesch.,’ 1837, s. 162.
[20] Rengger ‘Säugethiere,’ etc., s. 276. On the parentage of the guinea-pig, see also Isid. Geoffroy St.-Hilaire, ‘Hist. Nat. Gen.’ I sent to Mr. H. Denny of Leeds the lice which I collected from the wild aperea in La Plata, and he informs me that they belong to a genus distinct from those found on the guinea-pig. This is important evidence that the aperea is not the parent of the guinea-pig; and is worth giving, as some authors erroneously suppose that the guinea-pig since being domesticated has become sterile when crossed with the aperea.
[21] Although the existence of the Leporides, as described by Dr. Broca (‘Journal de Phys.,’ tom. ii. p. 370), has been positively denied, yet Dr. Pigeaux (‘Annals and Mag. of Nat. Hist.,’ vol. xx., 1867, p. 75) affirms that the hare and rabbit have produced hybrids.
[22] ‘Quadrupeds of North America,’ by Audubon and Bachman, 1846, p. 268.
[23] Loudon’s ‘Mag. of Nat. Hist.,’ vol. ix., 1836, p. 571; Audubon and Bachman’s ‘Quadrupeds of North America,’ p. 221.
[24] Flourens, ‘De l’Instinct,’ etc., 1845, p. 88.
[25] See ‘Annual Reports Zoolog. Soc.,’ 1855, 1858, 1863, 1864; ‘Times’ newspaper, Aug. 10th, 1847; Flourens, ‘De l’Instinct,’ p. 85.
[26] ‘Säugethiere,’ etc., s. 34, 49.
[27] Art. Brazil, ‘Penny Cyclop.,’ p. 363.
[28] ‘The Naturalist on the Amazons,’ vol. i. p. 99.
[29] A list of the species of birds which have bred in the Zoological Gardens from 1848 to 1867 inclusive has been published by Mr. Sclater in ‘Proc. Zoolog. Soc.,’ 1869, p. 626, since the first edition of this work appeared. Of Columbæ 51 species have been kept, and of Anseres 80 species, and in both these families 1 species in 2·6 have bred at least once in the 20 years. Of Gallinæ 83 species have been kept and 1 in 27 have bred; of 57 Grallæ 1 in 9 have bred; of 110 Prehensores 1 in 22 have bred; of 178 Passeres 1 in 25·4 have bred; of 94 Accipitres 1 in 47 have bred; of 25 Picariæ and of 35 Herodiones not one species in either group has bred.
[30] ‘Encyclop. of Rural Sports,’ p. 691.
[31] According to Sir A. Burnes (‘Cabool,’ etc., p. 51), eight species are used for hawking in Sinde.
[32] Loudon’s ‘Mag. of Nat. Hist.,’ vol. vi., 1833, p. 110.
[33] F. Cuvier, ‘Annal. du Muséum,’ tom. ix. p. 128.
[34] ‘The Zoologist,’ vol. vii.-viii., 1849-50, p. 2648.
[35] Knox, ‘Ornithological Rambles in Sussex,’ p. 91.
[36] ‘The Zoologist,’ vol. vii.-viii., 1849-50, p. 2566; vol. ix.-x., 1851-2, p. 3207.
[37] Bechstein, ‘Naturgesch. der Stubenvögel,’ 1840, s. 20.
[38] ‘Ornithological Biography,’ vol. v. p. 517.
[39] A case is recorded in ‘The Zoologist,’ vol. i.-ii., 1843-45, p. 453. For the siskin breeding, vol. iii.-iv., 1845-46, p. 1075. Bechstein ‘Stubenvögel,’ s. 139, speaks of bullfinches making nests, but rarely producing young.
[40] Yarrell’s ‘Hist. British Birds,’ 1839, vol. i. p. 412.
[41] Loudon’s ‘Mag. of Nat. History,’ vol. xix., 1836, p. 347.
[42] ‘Mémoires du Muséum d’Hist. Nat.,’ tom. x. p. 314: five cases of parrots breeding in France are here recorded. See also ‘Report Brit. Assoc. Zoolog.,’ 1843.
[43] ‘Annals and Mag. of Nat. Hist.,’ Nov. 1868, p. 311.
[44] ‘Stubenvögel,’ s. 105, 83.
[45] Dr. Hancock remarks (‘Charlesworth’s Mag. of Nat. Hist.’ vol. ii., 1838, p. 492), “it is singular that, amongst the numerous useful birds that are indigenous to Guiana, none are found to propagate among the Indians; yet the common fowl is reared in abundance throughout the country.”
[46] ‘A Week at Pert Royal,’ 1855, p. 7.
[47] Audubon, ‘American Ornithology,’ vol. v. pp. 552, 557.
[48] Mowbray on Poultry, 7th edit., p. 133.
[49] Temminck, ‘Hist. Nat. Gén. des Pigeons,’ etc., 1813, tom. iii. pp. 288, 382; ‘Annals and Mag. of Nat. Hist.,’ vol. xii., 1843, p. 453. Other species of partridge have occasionally bred; as the red-legged (P. rubra), when kept in a large court in France (see ‘Journal de Physique,’ tom. xxv. p. 294), and in the Zoological Gardens in 1856.
[50] Rev. E. S. Dixon, ‘The Dovecote,’ 1851, pp. 243-252.
[51] Temminck, ‘Hist. Nat. Gén. des Pigeons,’ etc., tom. ii. pp. 456, 458; tom. iii. pp. 2, 13, 47.
[52] Bates, ‘The Naturalist on the Amazons,’ vol. i. p. 193; vol. ii. p. 112.
[53] Temminck, ‘Hist. Nat. Gén.,’ etc., tom. ii. p. 125. For Tetrao urogallus, see L. Lloyd, ‘Field Sports of North of Europe,’ vol. i. pp. 287, 314; and ‘Bull. de la Soc. d’Acclimat.,’ tom. vii., 1860, p. 600. For T. scoticus, Thompson, ‘Nat. Hist. of Ireland,’ vol. ii. 1850, p. 49. For T. cupido, ‘Boston Journal of Nat. Hist.,’ vol. iii. p. 199.
[54] Marcel de Serres, ‘Annales des Sc. Nat.,’ 2nd series, Zoolog., tom. xiii. p. 175.
[55] Dr. Hancock, in ‘Charlesworth’s Mag. of Nat. Hist.,’ vol. ii., 1838, p. 491; R. Hill, ‘A Week at Port Royal,’ p. 8; ‘Guide to the Zoological Gardens,’ by P. L. Sclater, 1859, pp. 11, 12; ‘The Knowsley Menagerie,’ by D. Gray, 1846, pl. xiv.; E. Blyth, ‘Report Asiatic Soc. of Bengal,’ May 1855.
[56] Prof. Newton, in ‘Proc. Zoolog. Soc.,’ 1860, p. 336.
[57] ‘The Dovecote and Aviary,’ p. 428.
[58] ‘Ornithological Biography,’ vol. iii. p. 9.
[59] ‘Geograph. Journal,’ vol. xiii., 1844, p. 32.
[60] Loudon’s ‘Mag. of Nat. Hist.,’ vol. v., 1832, p. 153.
[61] ‘Zoologist,’ vols. v.-vi., 1847-48, p. 1660.
[62] ‘Transact. Entomolog. Soc.,’ vol. iv., 1845, p. 60.
[63] ‘Transact. Linn. Soc.,’ vol. vii. p. 40.
[64] See an interesting paper by Mr. Newman in the ‘Zoologist,’ 1857, p. 5764; and Dr. Wallace, in ‘Proc. Entomolog. Soc.,’ June 4th, 1860, p. 119.
[65] Yarrell’s ‘British Birds,’ vol. i. p. 506; Bechstein ‘Stubenvögel,’ s. 185; ‘Philosoph. Transact.,’ 1772, p. 271. Bronn (‘Geschichte der Natur,’ Band ii. s. 96) has collected a number of cases. For the case of the deer, see ‘Penny Cyclop.,’ vol. viii. p. 350.
[66] ‘Journal de Physiologie,’ tom. ii. p. 347.
[67] For additional evidence on this subject, see F. Cuvier in ‘Annales du Muséum,’ tom. xii. p. 119.
[68] Numerous instances could be given. Thus Livingstone (‘Travels,’ p. 217) states that the King of the Barotse, an inland tribe which never had any communication with white men, was extremely fond of taming animals, and every young antelope was brought to him. Mr. Galton informs me that the Damaras are likewise fond of keeping pets. The Indians of South America follow the same habit. Capt. Wilkes states that the Polynesians of the Samoan Islands tamed pigeons; and the New Zealanders, as Mr. Mantell informs me, kept various kinds of birds.
[69] For analogous cases with the fowl, see Réaumur, ‘L’Art de faire Eclore,’ etc., 1749, p. 243; and Col. Sykes, in ‘Proc. Zoolog. Soc.,’ 1832, etc. With respect to the fowl not breeding in northern regions, see Latham’s ‘Hist. of Birds,’ vol. viii., 1823, p. 169.
[70] “Mém. par divers Savans,” ‘Acad. des Sciences,’ tom. vi., 1835, p. 347.
[71] Youatt on Sheep, p. 181.
[72] J. Mills, ‘Treatise on Cattle,’ 1776, p. 72.
[73] Bechstein, ‘Stubenvögel,’ s. 242.
[74] ‘The Andes and the Amazon,’ 1870, p. 107.
[75] Crawfurd’s ‘Descriptive Dict. of the Indian Islands,’ 1856, p. 145.
[76] ‘Bull. de la Soc. d’Acclimat.,’ tom. ix., 1862, pp. 380, 384.
[77] For pigeons, see Dr. Chapuis, ‘Le Pigeon Voyageur Belge,’ 1865, p. 66.
[78] ‘Swedish Acts,’ vol. i., 1739, p. 3. Pallas makes the same remark in his ‘Travels’ (Eng. translat.), vol. i. p. 292.
[79] A. Kerner, ‘Die Cultur der Alpenpflanzen,’ 1864, s. 139; Watson’s ‘Cybele Britannica,’ vol. i. p. 131; Mr. D. Cameron, also, has written on the culture of Alpine plants in ‘Gard. Chronicle,’ 1848, pp. 253, 268, and mentions a few which seed.
[80] ‘Beiträge zur Kenntniss der Befruchtung,’ 1844 s. 333.
[81] ‘Nova Acta Petrop.,’ 1793, p. 391.
[82] ‘Cottage Gardener,’ 1856, pp. 44, 109.
[83] Dr. Herbert, ‘Amaryllidaceæ,’ p. 176.
[84] Gärtner, ‘Beiträge zur Kenntniss,’ etc., s. 560, 564.
[85] ‘Gardener’s Chronicle,’ 1844, p. 215; 1850, p. 470. Faivre gives a good résumé on this subject in his ‘La Variabilité des Espèces,’ 1868, p. 155.
[86] ‘Beiträge zur Kenntniss,’ etc., s. 252, 338.
[87] ‘Journal of Hort. Soc.,’ vol. ii., 1847, p. 83.
[88] ‘Beiträge zur Kenntniss,’ etc., s. 117 et seq.; Kölreuter, ‘Zweite Fortsetzung,’ s. 10, 121; ‘Dritte Fortsetzung,’ s. 57. Herbert, ‘Amaryllidaceæ,’ p. 355. Wiegmann ‘Ueber die Bastarderzeugung,’ s. 27.
[89] ‘Bastarderzengung,’ s. 356.
[90] ‘Teoria della Riproduzione,’ 1816, p. 84; ‘Traité du Citrus,’ 1811, p. 67.
[91] Mr. C. W. Crocker, in ‘Gardener’s Chronicle,’ 1861, p. 1092.
[92] Verlot, ‘Des Variétés,’ 1865, p. 80.
[93] Verlot, ibid., p. 88.
[94] Prof. Allman, Brit. Assoc., quoted in the ‘Phytologist,’ vol. ii. p. 483. Prof. Harvey, on the authority of Mr. Andrews, who discovered the plant, informed me that this monstrosity could be propagated by seed. With respect to the poppy, see Prof. Goeppert, as quoted in ‘Journal of Horticulture,’ July 1st, 1863, p. 171.
[95] ‘Comptes Rendus,’ Dec. 19th, 1864, p. 1039.
[96] ‘Gardener’s Chronicle,’ 1866, p. 681.
[97] ‘Theory of Horticulture,’ p. 333.
[98] Mr. Fairweather, in ‘Transact. Hort. Soc.,’ vol. iii. p. 406: Bosse, quoted by Bronn, ‘Geschichte der Natur,’ B. ii. s. 77. On the effects of the removal of the anthers, see Mr. Leitner, in Silliman’s ‘North American Journ. of Science,’ vol. xxiii. p. 47; and Verlot, ‘Des Variétés,’ 1865, p. 84.
[99] Lindley’s ‘Theory of Horticulture,’ p. 3?3.
[100] ‘Gardener’s Chronicle,’ 1865, p. 626; 1866, pp. 290, 730; and Verlot, ‘Des Variétés,’ p. 75.
[101] ‘Gardener’s Chronicle,’ 1843, p. 628. In this article I suggested the theory above given on the doubleness of flowers. This view is adopted by Carrière, ‘Production et Fix. des Variétés,’ 1865, p. 67.
[102] Quoted by Gärtner, ‘Bastarderzeugung,’ s. 567.
[103] ‘Gardener’s Chronicle,’ 1866, p. 901.
[104] Lindley, ‘Theory of Horticulture,’ pp. 175-179; Godron, ‘De l’Espèce,’ tom. ii. p. 106; Pickering, ‘Races of Man;’ Gallesio, ‘Teoria della Riproduzione,’ l816, pp. 101-110. Meyen, (‘Reise um Erde,’ Th. ii. s. 214) states that at Manilla one variety of the banana is full of seeds: and Chamisso (Hooker’s ‘Bot. Misc.,’ vol. i. p. 310) describes a variety of the bread-fruit in the Mariana Islands with small fruit, containing seeds which are frequently perfect. Burnes, in his ‘Travels in Bokhara,’ remarks on the pomegranate seeding in Mazenderan, as a remarkable peculiarity.
[105] Ingledew, in ‘Transact. of Agricult. and Hort. Soc. of India,’ vol. ii.
[106] ‘De la Fécondation,’ 1862, p. 308.
[107] Hooker’s ‘Bot. Misc.,’ vol. i. p. 99; Gallesio, ‘Teoria della Riproduzione,’ p. 110. Dr. J. de Cordemoy, in ‘Transact. of the R. Soc. of Mauritius’ (new series), vol. vi. 1873, pp. 60-67, gives a large number of cases of plants which never seed, including several species indigenous in Mauritius.
[108] ‘Transact. Linn. Soc.,’ vol. xvii. p. 563.
[109] Godron, ‘De l’Espèce,’ tom. ii. p. 106; Herbert on Crocus, in ‘Journal of Hort. Soc.,’ vol. i., 1846, p. 254: Dr. Wight, from what he has seen in India, believes in this view; ‘Madras Journal of Lit. and Science,’ vol. iv., 1836, p. 61.
[110] Wahlenberg specifies eight species in this state on the Lapland Alps: see Appendix to Linnæus’ ‘Tour in Lapland,’ translated by Sir J. E. Smith, vol. ii. pp. 274-280.
[111] ‘Travels in North America,’ Eng. translat., vol. iii. p. 175.
[112] With respect to the ivy and Acorus, see Dr. Broomfield in the ‘Phytologist,’ vol. iii. p. 376. Also Lindley and Vaucher on the Acorus, and see Caspary as below.
[113] ‘Annal. des Sc. Nat.,’ 3rd series, Zool., tom. iv. p. 280. Prof. Decaisne refers also to analogous cases with mosses and lichens near Paris.
[114] Mr. Tuckermann, in Silliman’s ‘American Journal of Science,’ vol. xlv. p. 1.
[115] Sir J. E. Smith, ‘English Flora,’ vol. i. p. 339.
[116] G. Planchon, ‘Flora de Montpellier,’ 1864, p. 20.
[117] On the non-production of seeds in England, see Mr. Crocker, in ‘Gardener’s Weekly Magazine,’ 1852, p. 70; Vaucher, ‘Hist. Phys. Plantes d’Europe,’ tom. i. p. 33; Lecoq, ‘Géograph. Bot. d’Europe,’ tom. iv. p. 466; Dr. D. Clos, in ‘Annal. des Sc. Nat.,’ 3rd series, Bot., tom. xvii. 1852, p. 129: this latter author refers to other analogous cases. See more especially on this plant and on other allied cases Prof. Caspary, “Die Nuphar,” ‘Abhand. Naturw. Gesellsch. zu Halle,’ B. xi. 1870, p. 40, 78.
[118] ‘Bastarderzeugung,’ s. 565. Kölreuter (Dritte Fortsetzung, s. 73, 87, 119) also shows that when two species, one single and the other double, are crossed, the hybrids are apt to be extremely double.
[119] ‘Teoria della Riproduzione Veg.,’ 1816, p. 73.
[120] ‘Bastarderzeugung,’ s. 573.
[121] Ibid., s. 527.