530 The Philippine Journal of Science 1920 
three-salt solutions containing no chlorides. Apparently normal 
seeds were obtained repeatedly by Johnston from buckwheat 
plants grown in one of Shive’s solutions, without any chloride . 12 
In spite of the fact that these experiments show that chlorine 
is not required in any considerable amount, it is probable that 
plants have never been grown without containing at least small 
amounts of chlorine. Most plants contain some chlorine and, 
besides typical saline plants, many contain relatively large 
amounts of chlorine in their ash . 13 Since seeds probably always 
contain small amounts of this element, it cannot be regarded 
as actually proved that it is absolutely unnecessary. However, 
the fact that chlorine is found in the ash must not, of course, 
be considered proof that it is essential. Thus, sodium, silicon, 
aluminium, barium, strontium, manganese, zinc, arsenic, copper, 
boron, bromine, iodine, fluorine, cobalt, nickel, tin, and lead are 
all found in plant ash, and yet no experiments have shown that 
these are necessary to induce growth. But a very recent paper, 
of which I have seen only a brief review, appears to furnish 
evidence that very small amounts of chlorine are necessary for 
buckwheat. Pfeiffer and Simmermacher 14 studied the signi- 
ficance of chlorine in fertilization experiments. Chlorine is re- 
ported as indispensable for the growth of buckwheat; but the 
amount of chlorine considered to be required was very small, 
and larger quantities of chlorine compounds were regarded as 
injurious. 
As with many other nonessential elements, plants may be 
altered in their manner of growth by supplying them with 
chlorine, in addition to the small amount contained in the seed. 
Such alterations may result in accelerated or retarded growth, 
increase or decrease in yield, etc., and chlorides may therefore be 
12 Johnston, E. S., Seasonal variations in the growth-rates of buckwheat 
plants under greenhouse conditions, Johns Hopkins Univ. Circular (March, 
1917) 211-217. 
13 Hopkins, C. G., Soil Fertility and Permanent Agriculture. New 
York (1910) 603. Wolff, Emil, Aschen-Analysen von landwirtschaftlichen 
Producten, Fabrik-abfallen und wildwachsenden Pfianzen. I. Theil. Berlin 
(1871) ; Aschen-Analysen von land- und fortswirtschaftlichen Producten. 
II, Theil. Berlin (1880). Mangin, M. H., Sur la ficoideglaciale (Mesem- 
brianthemum crystallinum) , Compt. rend. Paris 96 (1883) 80-83. 
14 Pfeiffer, Th., and Simmermacher, W., Landw. Versuchsst. 88 105-120. 
through Chem. Zentralbl. 1 (1916) 1186, and Chem. Abs. 11 (1917) 3365. 
