March 15, 1895.] 



SCIENCE. 



285 



spurs from one to three inches long. It 

 wtis plain that not more than twenty, at 

 the outside, of even this small number could 

 long persist. The main stem or trunk bore 

 forty-three branches, of which onlj- eleven 

 had much life in them, and even some of 

 this number showed signs of weakness. In 

 other words, in mj- little cherrj' tree, stand- 

 ing alone and having things all its own 

 way, only one bud out of every 175 suc- 

 ceeded in making even a fair start towards 

 a permanent branch. And this struggle 

 must have proceeded with greater severity 

 as the top became more complex, had I not 

 put an end to its ti-avail with the axe ! 



II. 



I am now ready to say that I believe bud- 

 variation to be one of the most significant 

 and important phenomena of vegetable life, 

 and that it is due to the same causes, oper- 

 ating in essentially the same way, which 

 underlie all variation in the plant world. 

 As some of you may not be familiar with 

 the technical use of the term, I will explain 

 that a bud-variety is an unusual or striking 

 form or branch appearing upon a plant ; or, 

 as Darwin put it, bud-variation is a term 

 used to " include all those sudden changes 

 in structure or appearance which occasion- 

 ally occur in full-grown plants in their 

 flower-buds or leaf-buds." A classical ex- 

 ample is the origination of the nectarine 

 from a branch of a peach ti'ee ; and one 

 often hears of Russet apples upon a certain 

 branch of Greening apple tree, of weeping, 

 variegated or cut-leaved shoots on otherwise 

 normal trees, or of potatoes that 'mix in the 

 hill.' Now, this matter of bud- variation 

 has been a most puzzling one to all writers 

 upon evolution who have touched upon it. 

 It long seemed to me to be inexplicable, 

 but I liope that you will now agree with me 

 in saying that it is no more unmtelligible 

 than seminal variation of plants, for I have 

 already shown that there is abundant asex- 



ual variation (of which bud-variation is 

 itself the proof), and that this variation 

 takes place as readily when the phj-ton is 

 growing upon a plant as when it is growing 

 in the soil. The chief trouble has been, in 

 the consideration of this subject, that per- 

 sons have obsei'S'ed and recorded only the 

 most marked or striking variations, or those 

 which appear somewhat suddenly (although 

 suddenness of appearance usually means 

 that the observer had not noticed it before), 

 and that they had therefore thought bud- 

 variation to be rare and exceptional. The 

 truth is, as I have said, that every branch 

 or phj-ton is a bud-variety, diflering in 

 greater or lesser degree from all other 

 phytons on the same plant. These difier- 

 ences, even when marked, may arise in 

 every part of the parent plant, as on stems 

 aerial and subterranean, from bulbs and 

 tubers, or even fi-om the adventitious buds 

 of roots ; and the characters of these vari- 

 eties are as various as those originating 

 from seeds. The nm-serj'man knows that 

 branches differ amongst themselves, for 

 he instructs his budders to cut buds only 

 from the top-most shoots of the nursery 

 rows in order that he may grow straight, 

 vigorous trees ; and every farmer's boy 

 knows that the reddest and earliest apples 

 grow on the uppermost branches, and his 

 father will always tell him that he should 

 never select cions from the center or lower 

 part of a tree. Every skilful horticulturist 

 will tell you that the character of the 

 orchard is determined very largely by the 

 judgment of the propagator in selecting 

 cions. To select out the extreme forms of 

 these variations and to attempt to explain 

 bud-variation by them is exactly like se- 

 lecting the extreme tj^pes of seminal 

 variations, and, by ignoring the lesser ones 

 and the intermediates, to attempt to build 

 thereon a theorj' of the variation of plants. 

 If you ask me why it is that the nectarine 

 was produced upon a branch of a peach 



