310 
JAMES GEERE DICKSON 
jars of four-gallon capacity were substituted for the smaller ones, 
allowing a greater production of plant substance since the number of 
plants was increased in proportion to the increase in size of the 
containers. 
The plants were grown in quartz sand, 98 percent of which passed 
through a sieve of 0.5 mm. mesh. The sand was digested six hours in 
10 percent hydrochloric acid and washed free of chlorides with distilled 
water. The composition of this washed sand was as follows: 
Si02 99-98% 
FeCls 014 
The average moisture-holding capacity of the air-dried sand after the 
above-described treatment was 25.1 percent by weight. 
Each jar was arranged with a four-inch glass funnel inverted in 
the bottom, into the stem of which was inserted a glass tube of one 
quarter inch diameter that extended above the top of the jar. A 
definite amount of sand was then poured around the funnel, after 
which the jars were covered with heavy paper until they were used 
for planting. 
Pedigreed Swedish select oats, Avena saliva aristata, were used in 
all of the experiments. The seed was sterilized in vacuo with 0.25 
percent mercuric chloride solution and washed in sterile distilled 
water until free from chlorides. The method of sterilization was 
similar to that employed by Hutchinson and Miller (1908), and when 
plated in bouillon agar after this treatment the seed showed no sign of 
infection. The seed after sterilization was germinated between cotton 
towels moistened with sterile distilled water until the primary root 
protruded beyond the seed coats. The seed was then again washed 
and planted; three plants were placed in each pot the first season, 
four the second, and eight the third. The sand in the jars, just pre- 
vious to the planting of the seedlings, had been brought to 60 percent 
of its moisture-holding capacity by pouring the culture solution over 
the surface of the sand, the weight of the jars being recorded. After 
planting the seedlings, the jars were again covered and allowed to 
stand until the seedlings appeared above the surface of the sand, when 
the jars were put on the balance and brought to their former moisture 
content with distilled water. A small waxed-paper tube was placed 
CaO. 
K2O. 
MgO 
P2O5. 
trace 
none 
none 
none 
