368 Stout: Bud-variation in Pelargonium 



sectoral arrangement with a more or less bilateral distribution of 

 the two kinds of cells. In certain types of Pelargonium the green 

 cells are outside as one or two layers covering the white cells. In 

 some individuals streaks of one of the tissues are mingled with the 

 other. 



Baur is able to interpret the conditions in these various forms 

 by using the conception developed by Winkler (1907) in his re- 

 markable discoveries regarding the so-called chimera-nature of 

 graft hybrids. Baur introduced the term periclinal chimera for 

 the condition where the peripheral cell-layers are different from 

 the enclosed tissues and sectoral chimera for the cases where there 

 is more or less of a bilateral or radial distribution. The term 

 hyper chimera, first suggested by Strasburger (1909), is used for 

 the cases where there is a more or less intimate mixture of the 

 different kinds of cells. 



On these various chimeras of Pelargonium, wholly green or 

 wholly white shoots may arise. This is due to the fact that the 

 two kinds of cells which are maintained by the cell divisions in the 

 meristematic regions become segregated in the growing points, 

 the process not being essentially different from that by which 

 peripheral, sectoral, or hyperchimeras arise. 



The various types of these Pelargonium chimeras are familiar 

 to horticulturists and have been propagated rather widely by 

 cuttings, thus preserving quite uniformly the different forms. The 

 periclinal chimeras having white peripheral cell layers are com- 

 monly cultivated forms on account of the striking effect of the 

 white-margined leaves. 



One of these varieties is known by the trade name of Madame 

 Sailer oi. During the summer of 1912 a plant of this type which 

 was grown in an outdoor bed at the propagating houses of the 

 New York Botanical Garden produced a branch in which the 

 relative position of the two kinds of cells is reversed. When the 

 cutting was made during the early part of the summer it possessed 

 only leaves with the white margin. In October of that year, 

 when first brought to the attention of the writer, the plant ap- 

 peared as shown in the photograph here reproduced (see plate 20). 

 Two branches, one the main and the other a lateral branch, bore 

 leaves with the white cell layers placed externally to the green as 



