From the Bulletin of ihkTokrby Botanical Club, 40: 367-372, //. 20. 19 July 1913. 1 



, , - . ,. ■ n 1 ' C1BRARY 



A case of bud-variation in Pelargonium NEw yo 



A. B. Stout eOTANlCAL 



liARDtiiN. 



(with plate 20) 



The precise nature of bud-variation is not satisfactorily known. 

 No adequate classification of the various kinds of bud-variation 

 has been made. Recent investigations regarding the nature of 

 plant chimeras indicate that some of the phenomena generally 

 considered as bud-variation are associated with chimeras and are 

 to be explained by the nature of the chimeras. Observations and 

 experiments are now being made at the New York Botanical 

 Garden on various types of bud-variation. In the studies on 

 Pelargonium one case has arisen which seems of special interest 

 in its bearing on the nature of bud-sports from plants that are 

 chimeras. 



Baur (1909 a and b; 191 1) has recently shown that the variega- 

 tion in the case of the "albomarginatae" varieties of Pelargonium 

 sonde is due to the presence of white and green cells which are 

 sharply distinct and which occupy a characteristic position in 

 relation to each other. It has been long known that the paler 

 tissue of these variegated plants owes its characteristics to a lack 

 of chlorophyl in its cells. Baur shows that the plastids are present 

 in the white cells but are colorless. 



Baur further claims that this arrangement of green and white 

 cells in the leaf can be explained by the arrangement of the corre- 

 sponding tissues in the growing point and actually shows that in 

 the plants whose leaves have layers of white cells on the exterior 

 there is in the apex of the stem a cap of white cells over the greener 

 cells beneath. In such plants the relative position of the white 

 and the green cells is maintained throughout the development of 

 the leaves. 



By further study Baur (1909 a; 191 1) found that in other cases 

 these two kinds of cells may be variously arranged with reference 

 to each other. In some plants various stems and leaves show a 



367 



