1921] GARDNER—GERMINATION 283 
whose germination is not increased simply by making the coats 
permeable, but requires the action of light or a suitable substitute 
to induce good germination. 
MICROCHEMISTRY 
The results of the various mechanical, physical, and chemical 
treatments of the light-sensitive seeds have offered few suggestions _ 
as to the nature of the effects of light on their constituents in 
inducing germination. The substitution of these various agencies 
for light has contributed little to an acceptable explanation of how 
light functions to bring about germination. These treatments, 
however, have served to localize the action of light and to determine 
the part of the seed affected. On the other hand, the microchemical 
examination yielded results which point to an acceptable explana- 
tion of the action of light on light-sensitive seeds. The outstanding 
findings of the microchemical studies were abundance of lipoids in 
each kind of seed and increased acidity of seeds incubated in light. 
Thus there are linked together light, lipoids, and increased acidity. 
ENZYMES ‘ 
Since starch and other carbohydrates were not found in the 
embryos of these seeds and in the endosperms of but two of them, 
it is not necessary to give serious consideration to the probable 
reaction of the products of their hydrolysis. Moreover, since 
proteolytic enzymes were found to be equally active in light and 
darkness in Nicotiana Tabacum and Verbascum Thapsus seeds, 
they need not be considered as important causes of increased 
acidity of the seeds incubated in light. It remains to be considered 
whether the products of the hydrolysis of the lipoids are the cause 
of the increased acidity in light. 
The development of acidity in the watery extract of an ity 
seed like that of the castor bean is generally considered evidence 
of the presence of lipase. Such development of increased acidity 
in light was demonstrated quantitatively for four of the five 
kinds of seeds, thus confirming the results of the microchemical 
examination, and giving reasonable ground for inferring that lipase 
splits the fats thus yielding fatty acids in seeds germinated in light. 
