49 



variants can spring from single cells. I think this even probable as regards some 

 of the many buds which develop from the bud-crown l ). Herewith is meant 

 the sheath of vigorously vegetating cambium-cells which is found in the callus 

 and the bark, just in the prolongation of the procambium- or cambium-cells of 

 truncated or thrown off buds or branches, which sheath is an active centrum 

 for the originating of new buds. For the rest, it is not the springing forth of 

 a bud or new individual from a single cell which is remarkable, but the fact that 

 this can take place from an already constitudet cell-group. That this really occurs, 

 and also, that a meristem constituted of many cells may be subject to the process 

 of variation, is proved by the following observations. 



At about ninety tat>t(rnum-buds which had developed as variants, nothing 

 particular was to be seen, but at eight or nine were found at the base a greater 

 or smaller number of bud-scales which could with certainty be recognised as 



bud-scales of adami (ad Fig. I A). 



This observation is easy and convincing, as 

 all parts of laburnum, hence the bud-scales too, 

 are covered with silverwhite hairs, especially at 

 the under- or back-side, while the full-grown 

 portions of adami are always devoid of hairs. In 

 all the cases, which I examined more minutely, 

 the line of demarcation between the adami- and 

 /o/w/vww-portion ran in an oblique direction, so 

 that the whole meristem belonged evidently to 

 laburnum. This was constantly confirmed by the 

 experience at the budding, as always pure labunmm- 

 shoots grew from these buds. 



In 1898 an extraordinarily great number of 

 laburnum-va.r\a.nts were formed on my adami-trees. 

 In consequence of the early pruning all the buds 

 were situated low enough to be easily examined 

 with the magnifying-glass. Two of them presented 

 themselves as in Fig. i B. The line of demarcation 

 went precisely over the middle of the bud scales 



Fig i. 



Two laburnum bud-variants on 

 a branch of Cytisus adami; the 

 lower bud A bears at its base 

 adami bud-scales, but is in the 

 higher portion pure laburnum; 

 the upper bud B is precisely for 



one half adami, for the other and not obliquely as in the eight cases above. 

 laburnum. The supposition that the said demarcation would 



also continue precisely over the middle of the 



meristem, proved right at the budding, for both the branches which sprung from 

 these buds in 1899, were exactly for one half, lengthwise, adami, for the other 

 half laburnum. 



One of these mixed branches has attained a length of about i Metre, and 

 produced more than 30 leaves with axillary lateral buds, of which about 15 belonged 

 to laburnum, the other 15 to adami. At its extremity was in the antumn of 18-59 an 

 open summer-bud, still for one half adami, for the other half laburnum; this 

 summer-bud was not closed with bud-scales, and died in the winter of 1899 1900. 



') Translated from the German Knospenkrone. 

 M. W. Beijerinck, Verzamclde Geschriften; Vicrde Deel. 



