Strout: BupD-VARIATION IN PELARGONIUM 371 
like those which are borne on the branches that are composed 
purely of green tissue. When the white is outside, the leaf is 
much smaller and more like those leaves which are composed only 
of white tissue. Several plants of Pelargonium Madame Salleroi 
of the same clone as the plant producing this bud-variation have 
been under observation in the propagating houses. Several of 
these have produced leaves composed wholly of white cells. These 
have been of practically the same shape and size as the variegated 
leaves on the same plant. The pure white cells are, of course, 
dependent upon the green cells for carbohydrate food. In the 
case of a chimera relationship with the green cells enclosed, there 
may be mechanical and chemical stimuli to the overlying white 
cells that result in a slightly larger leaf. This effect is, however, 
not marked. 
All the potentialities of a large and deeply lobed leaf are present 
in the green cells of a typical leaf of the Madame Salleroi variety. 
When these green cells get to the exterior those potentialities find 
expression, but as long as the peripheral layers of white are uni- 
formly maintained, there is no visible evidence that these poten- 
tialities exist. Their suppression may be due chiefly to mechanical 
limitations imposed by the peripheral layers of white cells which 
decrease the number of cell divisions. 
In the various plant chimeras there is an association of more or 
less independent and different kinds of cells. In the chimeras 
resulting from grafting, the two kinds of cells may be decidedly 
different, producing, when separate, two distinct types of leaves, 
but when associated together, forming leaves of still different 
Patterns. The various chimeras produced by Winkler (1907 and 
1909) and the chimera Crataegomespilus Asnieresti (see illustration 
by Baur 1911, pl. VIIZ) illustrate this phenomenon. In addition 
to such mechanical and physical interactions, Winkler (1910) has 
Presented some evidence that there may be a vegetative fusion of 
cells in graft tissues producing what he would consider as the only 
true graft-hybrid, and he further holds that hybrid modifications 
may also result from the migration of such substances as atropin or 
nicotine between stock and scion. 
These facts indicate that the general phenomena of plant 
chimeras have a very direct bearing on theories of morphogenesis 
