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Show 4.10 CONCLUSION AND SUMMARY CIIAP. XI. reproduce themselves by seed; and tho moRsy character has been transferred by crossing, from one species of rose to another. The Boston nectarine, which appeared as a bud-variation, producccl by seed a closely allied nectarine. We have however seen, on tho authority of Mr. Salter, that seed taken from a branch with leaves variegated through bud-variation, transmits this character very feebly; whilst many plants, which became variegated as seedling , transmit variegation to a largo 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 more cases, yet their total number is as nothing in comparison with that of seminal varieties. vVith seedling. 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 from being of no value were overlooked or not recorded. Accordingly I applied to two groat authorities on this subject, namely, to Mr. Hivers with respect to fruit-trees, and to Mr. Salter with respect to flowers. Mr. Hivers is doubtful. but doe~ not remember having noticed very slight variations in fruitbudR. 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 tho peach, which has been so carefully observed and of which such trifling seminal varieties have been propagated, yet this tree has repeatedly produced by budvariation 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. CIIAP. XI. OF THE CHAPTER. 411 To m~ s.urprise I hoar from Mr. Salter that he brings the groat prmc1ple of selection to boar on variegated plants propagat~ d. by buds, nnu has thus gr atly improved and fixed several mr~et1es. He informs me that at first a branch often produces vanegatcd leaves on one side alone, and that the ]eaves are ma~·kcrl only with an irregular edging or with a few lines of ~vlnte and yellow. 'l1o improve and fix such varieties, he finds It necessary to encourage tho buds at the bases of the most disti~ctly. marl~ed leaves, and to propagate from them alone. By foll~wmg With perseverance this plan during three or four successive seasons, n, distinct and fixed variety can generally be secured. Finally, the facts given in this chapter prove in how close and remaTkable a manner the germ of a fertilised seed and the small cellular mass forming a bud resemble each other in function,- in theh· powers of inheritance with occasional reversion - and i.n their capacity for variation of the same general nature: in ?bedwnce to the same laws. rrhis resemblance, or rather identity, 1s rendered far more striking if the facts can be trusted which apparently render it probable that the cellular tissue of one s~ecies or variety, when budded or grafted on another, may give r1se to a Lucl having an intermediate character. In this chapter we clearly see that variability is not necessarily contingent on sexual generation, though much more frequently its con? omitant than on bud-reproduction. We see that bud-variability 1s not solely dependent on reversion or atavism to long-lost characters, or to those formerly acquired from a cross, but that it is often spontaneous. But when we ask om·selves 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. END OF VOL. I. |