440 CONCLUSION AXD SUMMARY Chap. XI. 



from which the characters in question could have been derived 

 by a cross. We must attribute all such, cases to the appear- 

 ance 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 Eose, 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, 01 

 producing on the same plant differently coloured flowers, 

 are comparatively rare : Hopkirk 15B has seen this with Con- 

 volvulus tricolor ; and it is not uncommon with the Balsam 

 and annual Delphinium. According to Sir R. Sehomburgk, 

 plants from the warmer temperate regions, when cultivated 

 under the hot climate of St. Domingo, are eminently liable to 

 bud-variation. lam informed by Mr. Sedgwick that moss- 

 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. Varie- 

 gated leaves have, however, been observed under such circum- 

 stances ; 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. Gartner 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 



156 i Fi L>ra Anomala,' p. 164. Gesell. zu Konigsberg,' Bani vi., Feh 



li7 ' Schriften der physisch-okon. 3, 1865, s. 4. 



