Germination of Forest Trees 83 
Burns reached the conclusion that shade reduces the temperature 
of the soil and delays germination. Evidently there is a delicate 
balance between soil moisture and soil temperature, so that a 
slight deficiency in either might delay the germination process. 
In Burns’s case the temperature of the soil was so low, that in 
spite of the fact that there was sufficient soil moisture, germina- 
tion was delayed. In the present investigations soil temperature 
was kept at an optimum and measured differences in soil moisture 
were sufficient to result in an acceleration of germination in the 
shade cultures. One unfortunate fact about Burns’s work was 
that he failed to take into account soil moisture. In his experi- 
ments it must be assumed that there was sufficient soil moisture 
for germination. But there is nothing in his report which does 
not indicate that there was too much soil moisture. The recip- 
rocal relation between. soil temperature and soil moisture is well 
known. Furthermore there is an intimate relation between soil 
‘moisture and soil aeration and germination. Such factors as 
these were evidently not taken into account to explain the delay 
in germination in the experiments cited. 
3. Shade increases the length of the germination period. This 
bears out to a certain extent Pittauer’s experiments which showed 
that germination proceeds more rapidly in the light than in the 
shade. 
4. The germination curve of seeds sown in the shade rises more 
rapidly than the curve of seeds sown in the light. This con- © 
clusion does not agree with the results obtained by Pittauer. 
5. The final germination per cent. is usually Iigher in the case 
of seeds sown in the shade than those sown in the light. This 
conclusion, based upon abundant evidence, is not in accord with 
some work done by Atterberg which showed a greater germina- 
tion per cent. in the presence of light than in the absence of it. 
6. Light plays absolutely no part in the germination of tree 
seeds; in fact shade has been found to be exceedingly beneficial 
to germination, other factors being equal. In the work carried 
on by Burns already referred to, there are at least two state- 
ments that a certain amount of light is necessary for satisfactory 
germination. Whether he means to imply by the term “light ” 
