Monstrosities.—A large number of monstrous growths and of lesser anomalies are admitted by every one to be due to an arrest of development, that is, to the persistence of an embryonic condition. But many monstrosities cannot be thus explained; for parts of which no trace can be detected in the embryo, but which occur in other members of the same class of animals occasionally appear, and these may probably with truth be attributed to reversion. As, however, I have treated this subject as fully as I could in my ‘Descent of Man’ (ch. 1 2nd edition), I will not here recur to it.
When flowers which have normally an irregular structure become regular or peloric, the change is generally looked at by botanists as a return to the primitive state. But Dr. Maxwell Masters,[68] who has ably discussed this subject, remarks that when, for instance, all the sepals of a Tropæolum become green and of the same shape, instead of being coloured with one prolonged into a spur, or when all the petals of a Linaria become simple and regular, such cases may be due merely to an arrest of development; for in these flowers all the organs during their earliest condition are symmetrical, and, if arrested at this stage of growth, they would not become irregular. If, moreover, the arrest were to take place at a still earlier period of development, the result would be a simple tuft of green leaves; and no one probably would call this a case of reversion. Dr. Masters designates the cases first alluded to as regular peloria; and others, in which all the corresponding parts assume a similar form of irregularity, as when all the petals in a Linaria become spurred, as irregular peloria. We have no right to attribute these latter cases to reversion, until it can be shown that the parent-form, for instance, of the genus Linaria had had all its petals spurred; for a chance of this nature might result from the spreading of an anomalous structure, in accordance with the law, to be discussed in a future chapter, of homologous parts tending to vary in the same manner. But as both forms of peloria frequently occur on the same individual plant of the Linaria,[69] they probably stand in some close relation to one another. On the doctrine that peloria is simply the result of an arrest of development, it is difficult to understand how an organ arrested at a very early period of growth should acquire its full functional perfection;—how a petal, supposed to be thus arrested, should acquire its brilliant colours, and serve as an envelope to the flower, or a stamen produce efficient pollen; yet this occurs with many peloric flowers. That pelorism is not due to mere chance variability, but either to an arrest of development or to reversion, we may infer from an observation made by Ch. Morren[70] namely, that families which have irregular flowers often “return by these monstrous growths to their regular form; whilst we never see a regular flower realise the structure of an irregular one.”
Some flowers have almost certainly become more or less completely peloric through reversion, as the following interesting case shows. Corydalis tuberosa properly has one of its two nectaries colourless, destitute of nectar, only half the size of the other, and therefore, to a certain extent, in a rudimentary state; the pistil is curved towards the perfect nectary, and the hood, formed of the inner petals, slips off the pistil and stamen in one direction alone, so that, when a bee sucks the perfect nectary, the stigma and stamens are exposed and rubbed against the insect’s body. In several closely allied genera, as in Dielytra, etc., there are two perfect nectaries, the pistil is straight, and the hood slips off on either side, according as the bee sucks either nectary. Now, I have examined several flowers of Corydalis tuberosa, in which both nectaries were equally developed and contained nectar; in this we see only the redevelopment of a partially aborted organ; but with this redevelopment the pistil becomes straight, and the hood slips off in either direction, so that these flowers have acquired the perfect structure, so well adapted for insect agency, of Dielytra and its allies. We cannot attribute these coadapted modifications to chance, or to correlated variability; we must attribute them to reversion to a primordial condition of the species.
The peloric flowers of Pelargonium have their five petals in all respects alike, and there is no nectary so that they resemble the symmetrical flowers of the closely allied genus Geranium; but the alternate stamens are also sometimes destitute of anthers, the shortened filaments being left as rudiments, and in this respect they resemble the symmetrical flowers of the closely allied genus Erodium. Hence we may look at the peloric flowers of Pelargonium as having reverted to the state of some primordial form, the progenitor of the three closely related genera of Pelargonium, Geranium, and Erodium.
In the peloric form of Antirrhinum majus, appropriately called the “Wonder,” the tubular and elongated flowers differ wonderfully from those of the common snapdragon; the calyx and the mouth of the corolla consist of six equal lobes, and include six equal instead of four unequal stamens. One of the two additional stamens is manifestly formed by the development of a microscopically minute papilla, which may be found at the base of the upper lip of the flower of the common snapdragons in the nineteen plants examined by me. That this papilla is a rudiment of a stamen was well shown by its various degrees of development in crossed plants between the common and the peloric Antirrhinum. Again, a peloric Galeobdolon luteum, growing in my garden, had five equal petals, all striped like the ordinary lower lip, and included five equal instead of four unequal stamens; but Mr. R. Keeley, who sent me this plant, informs me that the flowers vary greatly, having from four to six lobes to the corolla, and from three to six stamens.[71] Now, as the members of the two great families to which the Antirrhinum and Galeobdolon belong are properly pentamerous, with some of the parts confluent and others suppressed, we ought not to look at the sixth stamen and the sixth lobe to the corolla in either case as due to reversion, any more than the additional petals in double flowers in these same two families. But the case is different with the fifth stamen in the peloric Antirrhinum, which is produced by the redevelopment of a rudiment always present, and which probably reveals to us the state of the flower, as far as the stamens are concerned, at some ancient epoch. It is also difficult to believe that the other four stamens and the petals, after an arrest of development at a very early embryonic age, would have come to full perfection in colour, structure, and function, unless these organs had at some former period normally passed through a similar course of growth. Hence it appears to me probable that the progenitor of the genus Antirrhinum must at some remote epoch have included five stamens and borne flowers in some degree resembling those now produced by the peloric form. The conclusion that peloria is not a mere monstrosity, irrespective of any former state of the species, is supported by the fact that this structure is often strongly inherited, as in the case of the peloric Antirrhinum and Gloxinia and sometimes in that of the peloric Corydalis solida.[72]
Lastly I may add that many instances have been recorded of flowers, not generally considered as peloric, in which certain organs are abnormally augmented in number. As an increase of parts cannot be looked at as an arrest of development, nor as due to the redevelopment of rudiments, for no rudiments are present, and as these additional parts bring the plant into closer relationship with its natural allies, they ought probably to be viewed as reversions to a primordial condition.
These several facts show us in an interesting manner how intimately certain abnormal states are connected together; namely, arrests of development causing parts to become rudimentary or to be wholly suppressed,—the redevelopment of parts now in a more or less rudimentary condition,—the reappearance of organs of which not a vestige can be detected,—and to these may be added, in the case of animals, the presence during youth, and subsequent disappearance, of certain characters which occasionally are retained throughout life. Some naturalists look at all such abnormal structures as a return to the ideal state of the group to which the affected being belongs; but it is difficult to conceive what is meant to be conveyed by this expression. Other naturalists maintain, with greater probability and distinctness of view, that the common bond of connection between the several foregoing cases is an actual, though partial, return to the structure of the ancient progenitor of the group. If this view be correct, we must believe that a vast number of characters, capable of evolution, lie hidden in every organic being. But it would be a mistake to suppose that the number is equally great in all beings. We know, for instance, that plants of many orders occasionally become peloric; but many more cases have been observed in the Labiatæ and Scrophulariaceæ than in any other order; and in one genus of the Scrophulariaceæ, namely Linaria, no less than thirteen species have been described in this condition.[73] On this view of the nature of peloric flowers, and bearing in mind certain monstrosities in the animal kingdom, we must conclude that the progenitors of most plants and animals have left an impression, capable of redevelopment, on the germs of their descendants, although these have since been profoundly modified.
The fertilised germ of one of the higher animals, subjected as it is to so vast a series of changes from the germinal cell to old age,—incessantly agitated by what Quatrefages well calls the tourbillon vital,—is perhaps the most wonderful object in nature. It is probable that hardly a change of any kind affects either parent, without some mark being left on the germ. But on the doctrine of reversion, as given in this chapter, the germ becomes a far more marvellous object, for, besides the visible changes which it undergoes, we must believe that it is crowded with invisible characters, proper to both sexes, to both the right and left side of the body, and to a long line of male and female ancestors separated by hundreds or even thousands of generations from the present time: and these characters, like those written on paper with invisible ink, lie ready to be evolved whenever the organisation is disturbed by certain known or unknown conditions.
REFERENCES
[1] Youatt on Sheep, pp. 20, 234. The same fact of loose horns occasionally appearing in hornless breeds has been observed in Germany; Bechstein, ‘Naturgesch. Deutschlands.’ b. 1 s. 362.
[2] Youatt on Cattle, pp. 155, 174.
[3] Youatt on Sheep, 1838, pp. 17, 145.
[4] I have been informed of this fact through the Rev. W. D. Fox on the excellent authority of Mr. Wilmot: see also remarks on this subject in an article in the ‘Quarterly Review,’ 1849, p. 395.
[5] Youatt, pp. 19, 234.
[6] ‘The Poultry Book,’ by Mr. Tegetmeier, 1866, p. 231.
[7] Loudon’s ‘Gardener’s Mag.,’ vol. x., 1834, p. 396: a nurseryman, with much experience on this subject, has likewise assured me that this sometimes occurs.
[8] ‘Gardener’s Chronicle,’ 1855, p. 777.
[9] Ibid., 1862, p. 721.
[10] Mr. Boner speaks (‘Chamois-hunting,’ 2nd edit., 1860, p. 92) of sheep often running wild in the Bavarian Alps; but, on making further inquiries at my request, he found that they are not able to establish themselves; they generally perish from the frozen snow clinging to their wool, and they have lost the skill necessary to pass over steep icy slopes. On one occasion two ewes survived the winter, but their lambs perished.
[11] See some excellent remarks on this subject by Mr. Wallace ‘Journal Proc. Linn. Soc.,’ 1858, vol. iii. p. 60.
[12] Dureau de la Malle ‘Comptes Rendus,’ tom. xli., 1855, p. 807. From the statements above given, the author concludes that the wild pigs of Louisiana are not descended from the European Sus scrofa.
[13] Capt. W. Allen, in his ‘Expedition to the Niger,’ states that fowls have run wild on the island of Annobon, and have become modified in form and voice. The account is so meagre and vague that it did not appear to me worth copying; but I now find that Dureau de la Malle (‘Comptes Rendus,’ tom. xli., 1855, p. 690) advances this as a good instance of reversion to the primitive stock, and as confirmatory of a still more vague statement in classical times by Varro.
[14] ‘Flora of Australia,’ 1859, Introduct., p. ix.
[15] ‘De l’Espèce,’ tom. ii. pp. 54, 58, 60.
[16] Mr. Sedgwick gives many instances in the ‘British and Foreign Med.-Chirurg. Review,’ April and July, 1863, pp. 448, 188.
[17] In his edit. of ‘Youatt on the Pig,’ 1860, p. 27.
[18] Dr. P. Lucas, ‘Héréd. Nat.,’ tom. ii. pp. 314, 892: see a good practical article on the subject in ‘Gard. Chronicle,’ 1856, p. 620. I could add a vast number of references, but they would be superfluous.
[19] Kölreuter gives curious cases in his ‘Dritte Fortsetzung,’ 1766, ss. 53, 59; and in his well-known ‘Memoirs on Lavatera and Jalapa.’ Gärtner, ‘Bastarderzeugung,’ ss. 437, 441, etc. Naudin in his “Recherches sur l’Hybridité,” ‘Nouvelles Archives du Muséum,’ tom. i. p. 25.
[20] Quoted by Mr. Sedgwick in ‘Med.-Chirurg. Review,’ April, 1861, p. 485. Dr. H. Dobell in ‘Med.-Chirurg. Transactions,’ vol. xlvi., gives an analogous case in which, in a large family, fingers with thickened joints were transmitted to several members during five generations; but when the blemish once disappeared it never reappeared.
[21] Verlot ‘Des Variétés,’ 1865, p. 63.
[22] ‘Nouvelles Archives du Muséum,’ tom. i. p. 25. Alex. Braun (in his ‘Rejuvenescence,’ Ray Soc., 1853, p. 315) apparently holds a similar opinion.
[23] Mr. Teebay in ‘The Poultry Book,’ by Mr. Tegetmeier, 1866, p. 72.
[24] Quoted by Hofacker ‘Ueber die Eigenschaften,’ etc., s. 98.
[25] Azara, ‘Essais Hist. Nat. de Paraguay,’ tom. ii. 1801, p. 372.
[26] These facts are given on the high authority of Mr. Hewitt, in ‘The Poultry Book,’ by Mr. Tegetmeier, 1866, p. 248.
[27] ‘The Poultry Book,’ by Tegetmeier, 1866, p. 97.
[28] ‘Gardener’s Chron. and Agricultural Gazette,’ 1866, p. 528.
[29] Ibid., 1860, p. 343. I am glad to find that so experienced a breeder of cattle as Mr. Willoughby Wood, (‘Gard. Chron.’ 1869, p. 1216), admits my principle of a cross giving a tendency to reversion.
[30] Sclater in ‘Proc. Zoolog. Soc.,’ 1862, p. 163.
[31] ‘History of the Horse,’ p. 212.
[32] ‘Mém. présentés par divers Savans à l’Acad. Royale,’ tom. vi. 1835, p. 338.
[33] ‘Letters from Alabama,’ 1859, p. 280.
[34] ‘Hist. Nat. des Mammiferes,’ 1820, tom. i.
[35] ‘Philosoph. Transact.,’ 1821, p. 20.
[36] Sclater, in ‘Proc. Zoolog. Soc.,’ 1862, p. 163: this species is the Ghor-Khur of N.W. India, and has often been called the Hemionus of Pallas. See also Mr. Blyth’s excellent paper in ‘Journal of Asiatic Soc. of Bengal,’ vol. xviii., 1860, p. 229.
[37] Another species of wild ass, the true E. hemionus or Kiang, which ordinarily has no shoulder-stripes, is said occasionally to have them; and these, as with the horse and ass, are sometimes double: see Mr. Blyth in the paper just quoted and in ‘Indian Sporting Review,’ 1856, p. 320: and Col. Hamilton Smith in ‘Nat. Library, Horses,’ p. 318; and ‘Dict. Class. d’Hist. Nat.,’ tom. iii. p. 563.
[38] Figured in the ‘Gleanings from the Knowsley Menageries,’ by Dr. J. E. Gray.
[39] ‘Darwin’sche Theorie und ihre Stellung zu Moral und Religion,’ p. 85.
[40] Cases of both Spanish and Polish hens sitting are given in the ‘Poultry Chronicle,’ 1855, vol. iii. p. 477.
[41] ‘The Poultry Book,’ by Mr. Tegetmeier, 1866, pp. 119, 163. The author, who remarks on the two negatives (‘Journ. of Hort.,’ 1862, p. 325), states that two broods were raised from a Spanish cock and Silver-pencilled Hamburgh hen, neither of which are incubators, and no less than seven out of eight hens in these two broods “showed a perfect obstinacy in sitting.” The Rev. E. S. Dixon (‘Ornamental Poultry,’ 1848, p. 200) says that chickens reared from a cross between Golden and Black Polish fowls, are “good and steady birds to sit.” Mr. B. P. Brent informs me that he raised some good sitting hens by crossing Pencilled Hamburgh and Polish breeds. A cross-bred bird from a Spanish non-incubating cock and Cochin incubating hen is mentioned in the ‘Poultry Chronicle,’ vol. iii. p. 13, as an “exemplary mother.” On the other hand, an exceptional case is given in the ‘Cottage Gardener,’ 1860, p. 388, of a hen raised from a Spanish cock and black Polish hen which did not incubate.
[42] ‘The Poultry Book,’ by Tegetmeier, 1866, pp. 165, 167.
[43] ‘Natural History Review,’ 1863, April, p. 277.
[44] ‘Essays on Natural History,’ p. 917.
[45] As stated by Mr. Orton, in his ‘Physiology of Breeding,’ p. 12.
[46] M. E. de Selys-Longchamps refers (‘Bulletin Acad. Roy. de Bruxelles,’ tom. xii. No. 10) to more than seven of these hybrids shot in Switzerland and France. M. Deby asserts (‘Zoologist,’ vol. v., 1845-46, p. 1254) that several have been shot in various parts of Belgium and Northern France. Audubon (‘Ornitholog. Biography,’ vol. iii. p. 168), speaking of these hybrids, says that, in North America, they “now and then wander off and become quite wild.”
[47] ‘Journal of Researches,’ 1845, p. 71.
[48] ‘Expedition to the Zambesi,’ 1865, pp. 25, 150.
[49] Dr. P. Broca, on ‘Hybridity in the Genus Homo,’ Eng. translat., 1864, p. 39.
[50] ‘Nouvelles Archives du Muséum,’ tom. i. p. 151.
[51] ‘Bastarderzeugung,’ s. 582, 438, etc.
[52] ‘Die Bastardbefruchtung . . . der Weiden,’ 1865, s. 23. For Gärtner’s remarks on this head, see ‘Bastarderzeugung,’ s. 474, 582.
[53] Prof. Weismann, in his very curious essay on the different forms produced by the same species of butterfly at different seasons (‘Saison-Dimorphismus der Schmetterlinge,’ pp. 27, 28), has come to a similar conclusion, namely, that any cause which disturbs the organisation, such as the exposure of the cocoons to heat or even to much shaking, gives a tendency to reversion.
[54] Yarrell, ‘Phil. Transact.,’ 1827, p. 268; Dr. Hamilton, in ‘Proc. Zoolog. Soc.,’ 1862, p. 23.
[55] ‘Archiv. Skand. Beiträge zur Naturgesch.’ viii. s. 397-413.
[56] In his ‘Essays on Nat. Hist.,’ 1838, Mr. Hewitt gives analogous cases with hen-pheasants in ‘Journal of Horticulture,’ July 12, 1864, p. 37. Isidore Geoffroy Saint-Hilaire, in his ‘Essais de Zoolog. Gen.’ (‘suites a Buffon,’ 1842, pp. 496-513), has collected such cases in ten different kinds of birds. It appears that Aristotle was well aware of the change in mental disposition in old hens. The case of the female deer acquiring horns is given at p. 513.
[57] ‘Cottage Gardener,’ 1860, p. 379.
[58] ‘Art de faire Eclore,’ etc., 1749, tom. ii. p. 8.
[59] Sir H. Holland, ‘Medical Notes and Reflections,’ 3rd edit., 1855, p. 31.
[60] See Steenstrup on the ‘Obliquity of Flounders’: in ‘Annals and Mag. of Nat. Hist.’ May, 1865, p. 361. I have given an abstract of Malm’s explanation of this wonderful phenomenon in the ‘Origin of Species’ 6th Edit. p. 186.
[61] Dr. E. von Martens, in ‘Annals and Mag. of Nat. Hist.’ March, 1866, p. 209.
[62] Darwin, ‘Balanidæ,’ Ray Soc., 1854, p. 499: see also the appended remarks on the apparently capricious development of the thoracic limbs on the right and left sides in the higher crustaceans.
[63] Mormodes ignea: Darwin, ‘Fertilisation of Orchids,’ 1862, p. 251.
[64] ‘Journal of Horticulture,’ July, 1864, p. 38. I have had the opportunity of examining these remarkable feathers through the kindness of Mr. Tegetmeier.
[65] ‘The Poultry Book,’ by Mr. Tegetmeier, 1866, p. 241.
[66] Carl Vogt, ‘Lectures on Man,’ Eng. translat., 1864, p. 411.
[67] ‘On Cattle,’ p. 174.
[68] ‘Natural Hist. Review,’ April, 1863, p. 258. See also his Lecture, Royal Institution, March 16, 1860. On same subject see Moquin-Tandon, ‘Eléments de Tératologie,’ 1841, pp. 184, 352. Dr. Peyritsch has collected a large number of very interesting cases, Sitzb. d. k. Akad. d. Wissensch.: Wien. b. LX. and especially b. LXVI., 1872, p. 125.
[69] Verlot, ‘Des Variétés,’ 1865, p. 89; Naudin, ‘Nouvelles Archives du Museum,’ tom. i. p. 137.
[70] In his discussion on some curious peloric Calceolarias, quoted in ‘Journal of Horticulture,’ Feb. 24, 1863, p. 152.
[71] For other cases of six divisions in peloric flowers of the Labiatæ and Scrophulariaceæ, see Moquin-Tandon, ‘Tératologie,’ p. 192.
[72] Godron, reprinted from the ‘Mémoires de l’Acad. de Stanislas,’ 1868.
[73] Moquin-Tandon, ‘Tératologie,’ p. 186.