160 HOW CROPS GROW. 
Wheat. a Pee rd Sane 
oa 
oy ; ‘v,, Ca inaiyels Analysis 
_ e seven : " 
ait ei pee analyses. Schulze. Schulze. 
Pte 2 caw esses 81.3 28.8 27.7 33.4 85.9 
Sodaiswovceeeeras 3.2 4.3 4.0 — 1.0 
Magnesia........ 12.3 11.6 15.0 11.8 13.7 
DAM ecciexins ieee 3.2 3.9 1.9 3.6 2.9 
Oxide of Iron... 0.7 0.8 1.0 0.8 0.7 
Phosphoric acid.46.1 45.6 47,1 46.9 45.0 
Sulphuric acid... 1.2 1.9 1.7 —_ —_ 
BiliCascensasicce dD 2.6 2.1 4 0.7 
Chiorine......... 0.2 q 0.1 _ _ 
; 0. 
By reference to the table, (p. 152,) it will be observed 
that the pea and bean kernel, together with the allied vetch 
_and lentil, (p. 379,)also nearly agree in ash-composition. 
So, too, the ashes of the root-crops, turnips, carrots, and 
beets, exhibit a general similarity of composition, as may 
be seen in the table, (p. 154-5). 
The seeds of the oil-bearing plants likewise constitute a 
group whose members agree in this respect, p. 379. 
5. The ash of the same species of plant is more or less 
variable in composition, according to circumstances. 
The conditions that have already been noticed as in- 
fluencing the proportion of ash are in general the same 
that affect its quality. Of these we may specially notice: 
a. The stage of growth of the plant. 
6. The vigor of its development. 
c. The variety of the plant or the relative development 
of its parts, and 
d. The soil or the supplies of food. 
a The stage of growth. The facts that the different 
parts of a plant yield ashes of different composition, and 
that the different stages of growth are marked by the 
development of new organs or the unequal expansion of 
those already formed, are sufficient to sustain the point 
now in question, and render it needless to cite analytical 
evidence. In a subsequent chapter, wherein we shall at- 
tempt to trace some of the various steps in the progressive 
