May, I92I] DICKSON — COMPOSITION OF OAT PLANT 267 
tions from the normal maturation of the plant. They sum up their results 
very well in the following statements : 
The character of the crop left to ripen depends very much more upon season than upon 
manuring. There is scarcely any difference in the composition of the truly and normally 
ripened seed. The wide range in the composition of the ash of the grain represents a cor- 
responding deviation from the normal development. 
0\ ZL I \ I 
A/Off n CaO.I rig 0.1 KO.I F 0.1 N 0.1 
Fig. I. Curves showing the average composition of grain and straw of plants grown • 
in the normal solution and in solutions with one nutrient element in each case reduced to 
one tenth the normal amount. 
Likewise LeClerc and Leavitt (1910) attribute the variations in com- 
position of wheat primarily to different climatic conditions and to the effect 
of these climatic factors upon plant growth and maturation. It is undoubt- 
' edly true that environmental factors which alter normal development and 
maturation have an extremely great influence upon the composition of 
