July i-sept. 3®, 1918 Illustrations xv 
Variations in the Moisture Content or the Surface Foot of a Loess p age 
Soil as Related to the Hygroscopic Coefficient 
Fig. 1. Map of a portion of the United States, showing annual precipitation, 
evaporation from a water surface, and frequency of drouths in a 20- 
year period, 1895-1914, to indicate the especially favorable location 
of the Nebraska Agricultural Experiment Station for soil-moisture 
studies. 454 
2. Diagram showing daily precipitation at Lincoln, Nebr., during the 
latter part of tie record-breaking drouth of the spring of 1910. 459 
3. Diagram showing moisture conditions in the surface 6 inches of soil in 
three adjacent fields at the Nebraska Agricultural Experiment Sta¬ 
tion during and just at the close of the record-breaking drouth in the 
spring of 1910. 460 
4. Diagram showing daily precipitation at Lincoln during the season of 
1912. The dates of sampling are indicated by asterisks.... 463 
5. Diagram showing ratio of moisture content to hygroscopic coefficient in 
the surface foot of soil on three adjacent areas at the Nebraska Agri¬ 
cultural Experiment Station during the season of 1912. The data 
illustrate also the relation of the distribution of moisture to both the 
plant cover and the preceding weather. 477 
Subsoiling, Deep Tilling, and Soil Dynamiting in the Great Plains 
Fig. i. Map of the Great Plains area, which includes parts of 10 States and con¬ 
sists of about 400,000 square miles of territory... 485 
2. Ratio of the yield for each crop at each station of plot E (subsoiled) to 
the mean of the yield of plot B (not subsoiled) and plot E (subsoiled) 
and the average of all crops at each station. 501 
3. Ratio of the yield for each crop at each station of plot E (subsoiled) to 
the mean of the yield of plot B (not subsoiled) and plot E (subsoiled) 
and the average of each crop at all stations. 502 
4. Diagram of plots in dynamiting experiment at Ardmore, S. Dak. 512 
Tissue Invasion by Plasmodiofhora brassicae 
Fig. 1. Diagram showing the course taken by the infecting plasmodia in a 
young cabbage root or stem... 552 
2. Diagram showing the course taken by the infecting plasmodia in cab¬ 
bage roots or stems that become infected after vascular elements are 
differentiated. 553 
Life History of Pemphigus populi-transversus 
Fig. 1. Diagram illustrating the seasonal history of Pemphigus populi-trans - 
versus at Baton Rouge, La... 588 
Stem Lesions Caused by Excessive Heat 
Fig. 1. Lesions on seedlings of Pinus ponderosa: Seedlings A and D were 
injured by the sun's rays condensed by a lens. B was injured by a 
hot wire, C by an incandesecent lamp, and E by the direct sun.... 596 
