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 
hyperchimera, 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 
Salleroit. 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 
