316 HOW CROPS GROW. 
At 65° the grains, clover, peas, and flax, began to sprout 
in one to two days; maize, beans, and sugar-beet, in 3 
days, and tobacco in 6 days. 
The time of completion varies with the temperature 
much more than that of beginning. It is, for example, ac- 
cording to Sachs, 
at 41- 55° for wheat and barley 40-45 days, 
«e 95-100° (79 ce ce ae 10-12 ce 
At a given temperature small seeds complete germina- 
tion much sooner than large ones. Thus at 55-60° the 
:rocess is finished with beans in 30-40 days. 
With maize in 30-35 days. 
‘¢ wheat ‘20-25 ‘ 
Sy clover! 8-10) 
These differences are simply due to the fact that the 
smaller seeds have smaller stores of nutriment for the 
young plant, and are therefore more quickly exhausted. 
Proper Depth of Sowing.—The soil is usually the me 
dium of moisture, warmth, etc., to the seed, and it affects 
germination only as it influences the supply of these 
agencies; it is not otherwise essential to the process. The 
burying of seeds, when sown in the field or garden, serves 
to cover them away from birds and keep them from drying 
up. In the forest, at spring-time, we may see innumerable 
seeds sprouting upon the surface, or but half covered with 
decayed leaves. 
While it is the nearly universal result of experience in 
temperate regions that agricultural seeds germinate most 
surely when sown at a depth not exceeding 1-3 inches, 
there are circumstances under which a widely different 
practice 1s admissible or even essential. In the light and 
porous soil of the gardens of New Haven, peas may be 
scwn 6 to 8 inches deep without detriment, and are 
thereby better secured from the ravages of the domestic 
pigeon. 
The Moqui Indians, dwell‘ng upon the table lands 
