249 



The same soil was used repeatedly, but it was carefully screened 

 and brought to "normal weight" before using. 



When a 30% saturation or less was desired, it was possible to 

 mix thoroughly the soil and the required amount of water without 

 puddling. Soil containing higher percentages of saturation could not 

 be prepared in this manner. The most convenient and efficient way of 

 securing a rapid and an equal distribution of the water in 50 and 75% 

 saturations was to place a thin layer of soil in the pan and spray it 

 with the proportionate amount of water, then add another layer and 

 spray again. This process was continued until the desired amount of 

 soil was in the pan and the proper amount of water added to give the 

 required moisture content. In a soil thus treated and protected to 

 avoid evaporation, the moisture was found uniformly distributed in 

 a short time. 



6. PI^ANTING 



The grains were planted in rectangular pans 35 cm. by 20 cm. 

 and 7 cm. deep. These pans were provided with closely fitting covers 

 in which w^ere openings for aeration. 



Each pan was furnished with 4 cu. dm. of prepared soil, in which 

 the grains were planted and then uniformly covered with an additional 

 cu. dm. of soil. The grains were placed one-half inch apart in rows 

 one inch apart. As an aid in securing an equal distribution and thus 

 in observing the behavior of the individual grains, a wire netting with 

 one-half inch mesh was placed on the surface of the soil and the grains 

 were inserted through it at regular intervals. They were thrust into 

 the soil in an upright position until the butts were flush with the sur- 

 face, and were then covered with the final cu. dm. of soil. To prevent 

 the grains from being pushed out of the loose soil of the low moisture 

 cultures by the growth of the root, the soil was slightly compressed by 

 placing a glass plate on the surface and applying a slight pressure with 

 the hand both before and after the addition of the soil used for cover- 

 ing. 



The gross weight of the pan and contents was then taken. The 

 pans used were provided with a shoulder just beneath the cover which 

 served to support a wire netting on which was kept moist blotting 

 paper. In this way the loss of water was greatly reduced, amount- 

 ing to only 2 or 3 c.c. in twenty-four hours. The original weight was 

 kept constant by the addition of water each morning by means of an 

 atomizer. 



The pans were kept covered during the period of germination 

 and until the seedlings were well through the soil. The critical period 

 of the test then being passed, the covers were removed to admit light. 



