VOLUME LXXI NUMBER 4 
DMS » YS 
BOTANICAL GAZETTE 
APRIL 192t 
EFFECT OF LIGHT ON GERMINATION OF 
LIGHT-SENSITIVE SEEDS 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 279 
Wricut A. GARDNER 
Historical 
Various explanations have been offered for the germination of 
light-sensitive seeds, and several conditions have been shown to 
favor or make possible the germination of such seeds. Rupture 
of coats, increased water supply, variation of quantity and intensity 
of light, reciprocal relation of heat and light, reaction of substratum 
and embryo, activation of enzymes, increased oxygen pressure, 
increased carbon dioxide pressure, and ‘‘certain inhibiting agencies” 
have been suggested as factors affecting the germination of light- 
Sensitive seeds. Although quite possible, it seems hardly probable 
that no one of these is the fundamental or controlling factor. It 
would seem quite probable that one or two of these agencies are 
fundamental and the others are accessory means of setting in 
motion the processes that finally bring about germination. Enzyme 
action has been suggested repeatedly as a fundamental cause of 
germination, but no one has ventured to demonstrate the relation 
of enzymes to the germination of light-sensitive seeds. 
An attempt has been made in this investigation to discover the 
fundamental relation of light to the germination of seeds, and to 
Show just what light does to start germination. The effect of light 
on the germination of seeds has interested botanists for many years. 
249 
