i go Smith and Butler.— Relation of 
essential to growth, and that the symptoms of potassium starvation, allowing 
for individual idiosyncrasies, were' the same in all the plants. 
The results which we have in turn obtained with wheat, corn, and 
buckwheat will confirm the findings of previous workers, and especially 
emphasize the importance of potassium being present at an early stage in 
the growth of the plant. 
I. The Effect of Absence of Potassium on Growth. 
In our study on the effect of absence of potassium on growth, two 
experiments were carried out with wheat and corn, respectively, and one 
with Japanese buckwheat. 
Experiment i. In this experiment Blue stem Wheat was grown 
twenty-one days in water culture. The plants were obtained from seed 
previously carefully selected for size and weighing not less than 20 mg. nor 
more than 35 mg. An analysis of several samples of this selected seed, 
containing from 800 to 1 ,400 seeds per sample, showed that the mean 
potassium content of a single seed was o-n mg. The seeds were germinated 
on paraffined cork sheeting 2 mm. thick, checkered with holes, which was 
floated on distilled water in a moist chamber also paraffin coated. The 
seeds were placed upon the cork with basal end protruding over the holes 
and the embryo facing upwards, so that upon germination the normal 
direction of growth was immediately assumed. This precaution made 
easier the transfer of the seedlings to the culture solutions, since the 
transfer was made when the plants were very young and it was essential 1 
that all the roots developed be immersed. Three days after the seeds were 
placed in the germinator they had grown sufficiently to permit transference 
to the culture solutions. The culture solutions were contained in glass jars 
10 cm. in diameter and 30 cm. high, containing approximately 1,600 c.c. 
The jars were said by the manufacturer to have been made from sand, soda- 
ash, and lime. Samples taken for analysis showed that the glass had a mean 
potassium content of o *66 per cent. The jars were covered with paraffined 
linen securely tied over the top as support for the plants. Six holes were 
punched in the linen, five equally spaced for the plants and the sixth 
excentrically for a tube 1 2 mm. in diameter and 25 cm. long, through which 
the water lost was added as required. In the preparation of the nutritive 
solutions only chemically pure salts were used, and they were all carefully 
examined spectroscopically for potassium, no more than a trace of this 
element being allowed. Care was also taken in the preparation of the 
distilled water to keep it free from potassium. 
In deciding on the type of nutritive solution to use we had first of all 
to select one that not only grew vigorous and healthy plants, but one that 
could also be modified so as to exclude potassium without any serious 
