536 The Philippine Journal of Science 1920 
For the preparation of the culture solutions, the required 
amount of each stock solution was drawn from a burette into 
a volumetric flask partially filled with distilled water, and the 
flask was finally filled to the mark with more water. For the 
cultures in series IV, in which culture solutions ranging from 
0. 50 to 7.00 atmospheres were employed, stock culture solutions 
of 7.00 atmospheres were prepared and the less-concentrated 
culture solutions were made by proper dilution. The culture 
solutions were poured from the volumetric flasks into the culture 
jars, and two drops of the suspension of ferric phosphate were 
added to each complete solution. The culture jars were wide- 
mouthed glass bottles of 250 cubic centimeters capacity, which 
had been used for several years in similar experiments. 
The plants . — The wheat seeds used in these studies were sup- 
plied by the Bureau of Plant Industry of the United States 
Department of Agriculture. The variety was “Fulcaster,” C. 
1. No. 1918, grown at the Arlington Experiment Farm, Arling- 
ton, Va., in 1915. The seeds were germinated in moist chambers 
and then transferred to a netting germinator. At the end of 
about five days, when the seedlings were from 8 to 10 centi- 
meters high, they were transferred from the germinator to the 
culture solutions. 
The internal differences between seedlings grown from the 
same stock of seed and exposed to pratically identical external 
conditions constitute a source of great difficulty in work with 
water-cultures. 35 To minimize such variations, seedlings were 
selected that were as nearly alike as possible, this selection being 
made on the basis of the appearance of the seedlings. Two 
selections were made, the first when the sprouted seeds were 
transferred to the netting germinators, and the second when 
the plants were transferred to the culture jars. 
Six seedlings were used in each culture. These were sup- 
ported by cotton in holes near the margin of the cork, the seed 
remnants remaining below the cork. To prevent entrance of 
light to the roots, the jars were covered with cardboard covers. 
The method of supporting the stem and leaves is important, 
because the rate of transpiration, and probably that of photosyn- 
“ This has been emphasized by Stiles. Stiles, W., On the relation be- 
tween the concentration of the nutrient solution and the rate of growth 
of plants in water culture, Ann. Bot. 29 (1915) 89-96. Observations on 
the influence of aeration of the nutrient solution in water culture experi- 
ments, with some remarks on the water culture method, New Phytol. 16 
(1917) 181-197. 
