Germination of Forest Trees 7 
The data for the mesophilous species are given in Table XII. 
The average figures at the bottom of the table show that germina- 
tion began in dense shade, followed by medium shade and open 
light; that the germination period is longest in the case of the 
dense shade; that germination began first in the loam and last in 
the gravel; and that the germination period was shortest in loam. 
Out of the 10 species listed in this table 7 germinated in the 
dense shade before they did in the open light, 4 out of 8 species 
showed longer germination period in the dense shade than in the 
open light ; and 7 showed shorter germination periods in the loam 
and sand than in the gravel. 
These three groups show exactly the same results so far as 
light and soil moisture go. From the standpoint of soil texture 
there are some interesting results. In the xerophilous species 
germination usually begins in the gravel, in the xero-mesophilous 
species it usually begins in the sand; and in the mesophilous 
species it usually begins in the loam, as the average figures and 
number of species in each case testify. In the xerophilous 
species the germination period is shortest in the loam and gravel, 
in the xero-mesophilous it is shortest in the gravel, and in the 
mesophilous species the period is shortest in the loam. That 
xerophilous species germinate sooner in the sand and gravel than 
in the loam is due undoubtedly to the amount of oxygen in these 
soils. This suggests that oxygen is more necessary for the ger- 
mination of xerophilous species than is the case in mesophilous 
ones. In the mesophilous species germination begins sooner in 
the loam indicating that soil moisture is more necessary to them 
than oxygen. In the case of the light and the soil moisture 
experiments it has been shown that favorable moisture conditions 
lengthen the time of germination. In these cases it was found 
that the shortest periods were in the open light and in the dry 
soil. This same theory is proven in the case of the soil texture 
experiments. It is well known that loam is favorable for ger- 
mination on account of its moisture-retaining properties and that 
gravel is favorable on account of its great amount of aeration. 
Sand is intermediate between these and combines enough of the 
soil moisture property of the loam with the aeration of the gravel 
