﻿CHLOROPHYLL AND GROWTH 



were brought into diffuse light with gradually 

 increasing intensity, the normal appearance 



was fi- 

 nally 

 resum- 

 ed. The 

 color of 

 the eti- 

 olated 

 leaves was of the cus- 

 tomary waxy yellow, 

 pon which the rtddish pur- 

 ple color areas characteris- 

 tic of the external tissue 

 were boldly apparent. The 

 spathe exhibited great vari- 

 ety of reaction, but in gen- 

 eral it did not attain full 

 development. This was 

 the invariable result if this 

 member alone was enclosed 

 in a covering excluding 

 light. And although not 

 responsive to the directive 

 action of light or gravity, 

 it assumed an upright or 

 outwardly recurved posi- 

 tion in darkness. 

 If plants with mature 

 leaves were placed in the dark chamber a re- 



FlG. 14. — Arissema tri 

 phyllum grown in an at 

 mosphere free from car 

 bon dioxide. 



