72 BOTANICAL GAZETTE [yULY 
Inheritance of albinism.—Baur’s has investigated the cause and inheritance 
of the white-margined condition found in the leaves of some of the common vari- 
eties of pelargonium and other forms. The white region of such leaves is com- 
posed of cells having colorless instead of green chromatophores, and the periphery, 
including the growing points, of such plants is found to be composed of 2 or 3 rows 
of colorless cells. Green cells are ordinarily descended from green, and white 
from white. 
When reproduced by seed the white-margined forms, since their sexual cells 
are from the peripheral white region, produce pure white offspring, which, having 
no chlorophyll, are incapable of growth. The occasional white branches produce 
pure white offspring; and the green branches produce pure green offspring. 
From the union of a “white” with a “green”’ sexual cell three kinds of plants 
are produced: pure green, which breed true; pure white; and green-white mosaics. 
It is probable that all belong to the last class, the pure white and green being 
extreme cases in which one type of cell has displaced the other at an early stage. 
In the hybrids which show a mosaic of white and green cells in their cotyledons, 
if the growing point is situated in a green part, then the plant produces only green 
parts thereafter; if in a white part, only white will be produced; if on the border 
between white and green, a sectorial chimera will be produced, one side of which 
will bear only green leaves and the other side only white. The production of a 
chimera of this sort by grafting was recently described by WINKLER" in Solanum. 
If the growing point is periclinally divided into green and white cells, then 
the leaves appearing will have the characteristic white margins. In other words, 
the white-margined varieties of pelargonium are periclinal chimeras, the white and 
green cells of which are both genetically descended from cells of their own sort. 
Islands of white tissue surrounded by green in the young seedlings show that 
the white cell may originate repeatedly from green cells. BAur’s hypothesis of 
the origin of these types of cells is that the fertilized egg contains both types of 
chromatophore, which are distributed chance-wise in subsequent cell. divisions. 
If a daughter cell thus comes to have only colorless chromatophores, then all its 
descendants will be colorless, 
tophores in a “white” 
: development of chromatophores in the embryo, and the form in which they may be 
present in the sexual cells, is greatly needed.—R. R. Gates. 
Ee Epwiy, Das Wesen und die Erblichkeitsverhaltnisse der “Varietates 
albomarginatae Hort.” yon P elargonium zonale. Zeits. Abst. u. Vererbungslehre 
13330-351. figs. 20. 1909. 
‘4 WINKLER, Hans, Ueber Pfro i ima Be; 
, . pfbastarde und pflanzliche Chimiren. 
Deutsch. Bot. Gesells, 25:568-576. figs. 3. 1907. See Bor. GazETTE 47:84. 1999 
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