Variation of animals and plants under domestication, v.2

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346 LAWS OF VARIATION. CUAP. XXVI. Monen has described 17 a marvellous flask-shaped flower of the Calceo­laria, nearly four inches in length, which was almost completely pelo~ie; it grew on the summit of the plant, with a normal flower on each s1de; Prof. We. twood also has described 18 three similar peloric flowers, which all occupied a central position on the flower-branches. In the Orchid~ous genus, Phalrenopsis, the terminal flower has been seen to become pelonc. In a Laburnum-tree I observed that about a fourth part of the racemes produced terminal flowers which had lost their papilionaceous structure. These were produced after almost all the other flowers on the same racemes bad mtbered. The most perfectly pelorised examples had six petals, each marked with black sb·ire like those on tho standard-petal. The keel seemed to resist the change more than the other petals. Dutrochet has described 19 an exactly similar case in France, and I believe these are the only two instances of pelorism in the laburnum which have been Tecorded. Dutrochet remarks that the racemes on this tree do not properly produce a terminal floweT, so that, as in the case of the Galeobdolon, their position as well as their structure are both anomalies, which no doubt are in some manner related. Dr. Masters has briefly described another legumi­nous plant,20 namely, a species of clover, in which the uppermost and central flowers were regular or had lost their papilionaceous structure. In some of these plants the flower-heads were also proliferous. Lastly, Linaria produces two kinds of peloric flowers, one having simple petals, and the other having them all spurred. The two foTms, as Naudin remarks, 21 not mrely occur on the same plant, but in this case the spurred form almost invariably stands on the summit of the spike. The tendency in the terminal or central flower to become peloric more fre­quently than other flowers, probably Tesults from "the bud which stands "on the end of a shoot receiving the most sap; it grows out into a stronger "shoot than those situated lower down." 22 I have discussed the connection between pelorism and a central position, partly because some few plants are known normally to produce a te1·minal flower different in structure from the lateral ones; but chiefly on account of the following case, in which we see a tendency to variability or to reversion connected with the same position. A great judge of Auriculas 28 states that when an Auricula throws up a side bloom it is pretty sure to keep its character; but that if it grows from the centre or heart of the plant, whatever the colour of the edging ought to be, "it is just as likely to come in any other "class as in the one to which it properly belongs." This is so notorious a then to sow tho seed separately, and observe whether the one or the other lot of ~codlings varieJ. tho most. 17 Quoted in 'Journal of IIorticultme,' Feb. 2-:1:, 1863, p. 152. 18 ' Gardener's Chronicle,' 1866, p. 612. For tho PlwJreuopsis, see idem, 1867, p. 211. 19 1\Icmoires .. des Vegcta ux,' 1837, tom. ii. p. L70. 2o 'Journal of Hor ticulture,' July 23, 18C1, p. 311. 21 'Nouvelles Archives du l\lnseum,' tom. i. p. 137. 22 Hugo von 1\Iohl, 'The Vegetable 0 ' 11,' Eng. tr., 1852, p. 76. 23 Tho Rev. H. H. Dombrain, in · J ourual of Horticulture,' 1861, Juno 4th, p. 17'1; and Juno 25th, p. 2fH; 1862, April 2Dih, p. 83. CHAP. XXVI. RELATIVE POSITION OF PARTS. 347 fact, that some florists regularly pinch off the central trusses of flowers. Whether in the highly improved varieties the departure of the central trusses from their proper type is due to reversion, 1 do not know. MT. Dombrain insists that, whatever may be the commonest kind of imper­fection in each variety, this is generally exaggerated in the central truss. Thus one variety "sometimes has the fault of producing a little green " floret in the centre of the flower," and in central blooms these become excessive in size. In some central blooms, sent to me by Mr. Dombrain, all the organs of the flower were rudimentary in structure, of minute size, and of a green colour, so that by a little further change all would have been converted into small leaves. In this case we clearly see a ten­dency to prolification-a term which, I may explain to those who have never attended to botany, means the production of a branch or flower, or bead of flowers, out of another flower. Now Dr. Masters 24 states that the central or uppermost flower on a plant is generally the most liable to prolification. Thus, in the varieties of the Auricula, the loss of their proper character and a tendency to prolification, and in other plants a ten­dency to prolification and pelorism, are all connected together, and are clue either to arrested development, or to reversion to a former condition. The following is a more interesting case ; MetzgeT 25 cultivated in Ger­many several kinds of maize brought from the hotteT parts of America, and he found, as has been previously described, that in two or three generations the grains became greatly changed in form, size, and colour; and with respect to two races he expressly states that in the first genera­tion, whilst the lower grains on each head retained their proper character, the uppermost grains already began to assume that character which in the third generation all the grains acquired. As we do not know the aboriginal parent of the maize, we cannot tell whether these changes are in any way connected with reversion. In the two following cases, reversion, as influenced by the position of the seed in the capsule, evidently acts. The Blue Imperial pea is the offspring of the Blue Prussian, and has larger seed and broader pods than its parent. Now Mr. Masters, of Canterbury, a careful observer and a raiser of new varieties of the pea, states 26 that the Blue Imperial always has a strong tendency to revert to its parent-stock, and the reversion "occurs in this manner: the last (or uppermost) pea in the pod is fre­" quently much smaller than the rest; and if these small peas are care­" fully collected and sown separately, very many more, in proportion, " will revert to their origin, than those taken from the other parts of the " pod." Again M. Chatezr says that in raising seedling stocks he succeeds in getting eighty per cent. to bear double flowers, by leaving only a few of the secondary branches to seed; but in addition to this, "at the time " of extracting the seeds, the upper portion of the pod is separated and 2 ~ ' Transact. Linn. Soc.,' vol. xxiii., LSoi, p. 360. ~5 'Dio Getreidearteu ' 1 fH::l, s. 208, 20H. ' 26 ' Gardener's Chronicle,' 1850, p. Hl8. 27 Quoted in ' Gardener's Chron.,' 18G6, p. 71.