268 Non-Isolable Races. 
viously results in an insufficient assimilation of carbonic 
acid gas. Thus the variegated parts grow less vigor- 
ously and are less resistant than the corresponding green 
ones. The Cy perns alter nifolius of our greenhouses, the 
Aspidistra elatior and a number of other favorite varie- 
ties show this clearly. Arundo do mix often attains a 
height of three or more meters whereas its striped vari- 
ety is scarcely half that height. Leaves of the variegated 
Aspidistra very often have one of their longitudinal 
halves green, but the other colorless. In such cases the 
leaf is distorted owing to the insufficient growth of the 
colorless half. The same thing happens in many other 
cases. 
The yellow leaves and parts of leaves, however, are 
not entirely without the green coloring matter, nor wholly 
without the power of assimilation. Most of them give 
a green extract when put into alcohol, and if examined 
under the microscope patches of green tissue can be found 
here and there, especially near the veins. The power to 
sustain life, however, is often lacking and the leaves die 
shortly after their growth is completed. Therefore, a 
high degree of the anomaly is not in favor, because the 
plants which possess it often become disfigured by the 
edges of their leaves turning brown. Many plants in 
which the variegation has gone too far die in their very 
early stages, while others have not sufficient strength to 
flower and bear seed. This latter circumstance is of 
special interest because it follows that plants with a high 
degree of variegation as a rule can have no part in the 
propagation of the variety. 1 In the opinion of some 
1 It is perhaps scarcely necessary to state that these remarks do 
not apply to brown and purple leaves or those with red spots. For 
information on this point see STAHL'S excellent article Ueber bunte 
Laubbldttcr, Ann. Jard. Bot. Buitenzorg., Vol. XIII, Pt. 2, 1896, p. 137. 
