1914] Guy West Wilson 205 



ous plants on the lower heated soils. For this reason it was im- 

 practicable to keep the pots under observation until flowering time. 



Experiment hi. Rye. The plants in this experiment were 

 first photographed at the end of a week (Fig. 6) and again at the 

 end of the second week (Fig. 7). The plants were all very healthy, 

 highly colored and sturdy. In the low-temperature pot (95 ) the 

 plants were slightly more colored than those of the check, and 

 showed a better and more even growth. In the two higher-tem- 

 perature pots the growth was retarded and the plants were weaker, 

 but their heightened color showed the effect of the higher percentage 

 of soluble matter in the soil on which they were grown. Germina- 

 tion was seriously retarded by heating to 175 . From the various 

 cultures made of rye it would appear that there was a slight acceler- 

 ation of growth on the soil subjected to a temperature of 95 , while 

 the higher temperatures showed a proportionate retardation. These 

 plants were severely attacked by mildew, those on the soils which 

 had been heated to the higher temperatures suffering most seriously. 



Experiment iv. Barley. At the end of the first week, when 

 the barley plants were photographed (Fig. 8), germination was 

 about equal in all the pots. The rate of growth varied considerably. 

 The plants on the soil that had been heated to 95 ° were slightly 

 taller than the check, those on the soil of the next member of the 

 series (135 ) were slightly retarded in growth, and those on the last 

 one ( 1/5°) were markedly retarded in growth. While no repetition 

 of this experiment was attempted, the results indicated that the 

 growth of barley was affected less than that of any of the small 

 grains grown in these soils, yet the highest temperature caused a 

 serious retardation. It is probable that the optimum for barley is 

 slightly higher than for the other plants which were used in this 

 series of experiments. 



General discussion. While the soil used in these experiments 

 was, from the agricultural standpoint, a very poor loam, all the 

 crops grown were those which might be considered best adapted to 

 the type of soil used. Barley, alone of the series, is usually re- 

 garded as demanding a soil which might be termed rich, while 

 buckwheat and rye are noted for their ability to grow on soils low 

 in plant food. Wheat, however, demands a richer soil than the last 

 named crops. 



