50 



The second branch has become about !/ 2 M. long, and bore more than 12 leaves 

 with axillary buds, again belonging for one half to laburnum, for the other to adami. 

 In the autumn of 1899 a closed winter-bud with bud-scales was formed at the 

 extremity. Though the line of demarcation seemed also to go over the middle of this 

 terminal bud, a laburnum-branch developed from it in the summer of 1900, which 

 only at the base bore some ada mi-leaves, so that the separation within the bud 

 must have run obliquely and divided the meristem into a larger laburnum- and a 

 smaller adami-portion. 



This description proves that the two halves of the mixed branches* have 

 each grown from an independent half of the meristem, which half cannot consist 

 of less than one cell, so that the continued growing of the branches with one 

 terminal cell is out of question, accordingly it is certain that the branches of 

 Cytisus adami grow with at least 2., and probably many more meristem cells. 



The two separating lines between laburnum and adami which are seen over the 

 full length of the mixed branches*, easily discernible on the bark as the confines 

 between a portion set with hairs and another without, ran in 1899 for the greater 

 part of course between the leaves, but in some places also through the leaves 

 themselves. Some of these mixed leaves* were situated exactly for one half on the 

 laburnum- for the other on the adami-portion of the branch. In this case the trifoliate 

 leaf was as exactly for one half an adami- and for the other a laburnum-\eai, and 

 over the whole length of the petiole and the midrib of the terminal leaflet the 

 line of demarcation was distinctly discernible. This would, if necessary, be sufficient to 

 prove that also each leaf takes birth from at least two, and probably more meristem 

 cells. But the pluricellular origin of the leaves of the higher plants has, so far as I 

 know, never been called in question, though this has been the case concerning the 

 origin of the lateral buds. 



So, it was of importance to establish whether the axillary buds of these 

 mixed leaves*, exactly placed on the confine, would likewise produce mixed 

 branches*, by which the question would be answered if one bud might spring forth 

 from two or more cells at a time. The answer was not dubious : all the buds, 

 placed in the axils of the leaves, which were for one half laburnum, for the other 

 adami, produced, in the summer of 1900, as well laburnum- as adaii-\eaves, and in 

 this case, too, some leaves again were mixed, namely partly adami- partly /a&urnum-lea,ves. 



In most cases the line of demarcation went very obliquely through the mixed 

 buds of this second generation, so that the whole meristem early in the year 

 consisted of only adami or only laburnum. In one of these buds however the boundary 

 line went precisely through the middle, but this bud contained an inflorescence 

 of which the summit had died off in the winter of 1899 1900. At the base were 

 however pure laburnum- and pure adawi-fiowers, and one flower was precisely for one 

 half laburnum, for the other adami, so that also flowers evidently spring not from one 

 cell, but from a cell-group. 



The preceding description proves that in the springing forth of the laburn'tm- 

 variant from Cytisus adami, as well a whole meristem may be concerned as half of it, 

 and that the cause which gives rise to the appearance of a bud-variant is active 

 when the meristem is completely formed, and not in the far-back moment when the 

 cell-group, which later manifests itself as a meristem, was still a single cell. For if 



