THE ASH OF PLANTS. 195 
The recommendation to supply silex to grain crops, in 
order to stiffen the straw and prevent falling of the crop 
oefore it ripens, either by directly applying alkali-silicates, 
or by the use of fertilizers and amendments that may 
render the silica of the soil soluble, must, accordingly, be 
sonsidered entirely futile from the point of view of the needs 
of the crop, as it is from that of the resources of the soil. 
Chlorine.—As has been mentioned, both Nobbe and 
Leydhecker found that buckwheat grew quite well up to 
the time of blossom without chlorine. From that period 
on, in absence of chlorine, remarkable anomalies appeared 
in the development of the plant. In the ordinary course 
of growth, starch, which is organized in the mature leaves, 
does not remain in them to munch extent, but is transferred 
to the newer organs, and especially to the fruit, where it 
also accumulates in large quantities. In absence of chlo- 
rine, in the experiments of Nobbe and Leydhecker, the 
terminal leaves became thick and fleshy, from extraordinary 
development of cell-tissue, at the same time they curled 
together and finally fell off, upon slight disturbance. The 
stem became knotty, transpiration of water was suppress- 
ed, the blossoms withered without fructification, and the 
plant prematurely died. The fleshy leaves were full of 
starch-grains, and it appeared that in absence of chlorine 
the transfer of starch from the foliage to the flower and 
fruit was rendered impossible; in other words, chlorine (in 
combination with potassium or calcium) was concluded to 
be necessary to, was, in fact, the agent of this transfer. 
Knop believes, however, that these phenomena are due te 
some other cause, and that chlorine is not essential to the 
perfection of the fruit of buckwheat, (see p. 182). 
Iron.—We are in possession of some interesting facts, 
which appear to throw light upon the function of this 
metal in the plant. In case of the deficiency of this ele- 
ment, foliage loses its natural green color, and becomes pale 
or white even in the full sunshine. In absence of iron a 
