224 
Smith and Butler. — Relation of 
Japanese buckwheat obtained from seed containing o-o 6 mg. suffered a 
corresponding loss in weight only when potassium was withheld six days, and 
an Early Dent Corn seed containing 0-85 mg. of potassium gave a plant that 
only showed similar stunting when potassium was withheld twelve days. If 
the potassium content of the seed were the determining factor, then starvation 
symptoms should have appeared in the following order — buckwheat, wheat, 
corn. It should, however, be remembered that wheat and corn are physio- 
logically alike in their potassium requirement, while buckwheat does not 
resemble these plants at all in its potassium requirement. Potassium- 
starved wheat and corn are able to effect a more economical use of potassium 
than buckwheat, though they do not recover from potassium starvation as 
readily. It will be remembered that, as potassium starvation was prolonged 
in wheat and corn, the dry matter produced per gramme of potassium utilized 
increased ; in the case of buckwheat, however, the potassium requirement 
changes little, as the following figures show : 
In the full nutritive solution there was formed by 1 grm. potassium 
16.86 grm. dry matter. 
When potassium was added after 3 days there was formed by 1 grm. potassium 
16-19 grm. dry matter. 
„ „ „ „ 6 ,, „ „ by 1 grm. potassium 
17.16 grm. dry matter. 
„ „ ,, ,, 9 „ „ ,, by 1 grm. potassium 
18- 60 grm. dry matter. 
,, ,, , ,, 12 „ ,, ,, by 1 grm. potassium 
19- 6 r grm. dry matter. 
,, ,, by 1 grm. potassium 
112-23 b rm - dry matter. 
When potassium was absent 
In the case of buckwheat, therefore, we have a plant which, while 
unable to gain in weight as readily as wheat and corn in the absence of 
potassium, is nevertheless better able to recover from the effects of potas- 
sium starvation. Nobbe, Schroeder, and Erdemann 1 noticed that buckwheat 
was practically unable to synthesize starch in the absence of potassium, but 
that this function was resumed when potassium was added to the nutritive 
solution, and we have shown that starved plants renew growth when 
potassium is added to the nutritive solution. On the other hand, we have 
also shown that in the absence of potassium wheat continues to synthesize 
starch, but does not recover so readily from potassium starvation. Never- 
theless, the role of potassium in metabolism must be the same in wheat, 
corn, and buckwheat ; and of the roles assigned to potassium preponderance 
should not be given, it seems to us, to synthesis of starch, though it must be 
recognized that a disturbance in the normal functioning of any metabolic or 
catabolic process usually has a more or less sensible effect on all life- 
processes of the cell, but the magnitude of the disturbance and the exact 
secondary reactions that will ensue need not of necessity be invariably 
the same. 
Loc. cit. ante. 
