372 Strout: BUD-VARIATION IN PELARGONIUM 
and that cellular interaction is a potent factor in influencing cell 
differentiation and in determining the physical characteristics of 
such organs as leaves. 
The bud-sports which arise from the various Pelargonium 
chimeras are, we may say, rather simple cases of variation due to 
a mechanical rearrangement of the kinds of cells already present. 
Their appearance is a confirmation of the rule that like produces 
like in its application to cell lineage rather than evidence of spon- 
taneous somatic mutation or variation. In this case the real 
variation occurs when the white cells appear as the progeny of 
green cells. The frequency of this spontaneous variation in 
Pelargonium (and in other cases as well) and the real nature and 
the causes of the process.are problems for future solution. 
New YorK BOTANICAL GARDEN. 
LITERATURE CITED 
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(1909b). Propfbastarde, “ae: oe Pe und Hyperchi- 
maren. Ber. Deuts. Bot. Ges. 27: 603-605. 
pach Einfiihrung in die experimentelle Vererbungslehre. 
Strasburger, E. (1909). Meine Sgelaeea zur Frage der Propf-_ 
bastarde. Ber. Deuts. Bot. Ges. 27: 511-528 
Winkler, H. (1907). Uber Propfbastarde und pilanalich Chimaeren. 
Ber. Deuts. Bot. Ges. 25: 568-576. 
(1909). Weitere Mitteilungen iiber Propfbastarde Zeits. Bot. 
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(1910). Ueber das Wesen der Bluse Ber. Deuts. 
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