110 
Research Bulletin No. 3 
Experiment 2. — In this a 6-foot cylinder filled with H O sur- 
face soil and H O subsoil was used. It had been filled and satu- 
rated along with those described on pages 80 and 81. On February 
28. 1911, two mesquite plants were placed in this. In transplant- 
ing the mesquites the surface soil was removed to a depth of 6 
inches and the whole of the soil from the two flowerpots intro- 
duced so as not to disturb the roots of the mesquites, after which 
the open spaces were filled with the H O surface soil which had 
just been removed. A day mulch of H O surface soil was then 
added. Thus there was some Lincoln surface soil in the first 6 
inches of this cylinder but the quantity was small and its relative 
hygroscopicity was so similar to that of the H O surface soil that 
it might be considered as part of the latter. 
The larger of the two plants grew much the more rapidly, but 
both did well until early in April, when the smaller began dying. 
The latter gradually declined until on June 6 it appeared quite 
dead. Its height was 14.5 inches. The other continued to grow 
until it was 47.5 inches high; then it began to drop its leaves, 
one by one, but on June 17 it still appeared quite vigorous. At 
the end of June it had lost most of its leaves and on the evening 
of July 5, a day when the maximum temperature in the green- 
house reached 130° F., it appeared to have been killed. On July 
12, the plant being quite dry, it was removed and the cylinder 
opened. About a dozen leaves remained on the plant when it 
died. 
A small crevice extended to the 9th inch but there was none 
below. Roots were well distributed thruout the subsoil. ( See 
Table 28 and figure 36.) 
The subsoil, as shown in Table 30 and in figure 22, was very 
dry. the moisture content being uniform and distinctly below the 
hygroscopic coefficient. There can be little doubt but that some 
little time before the death of the larger plant all free moisture 
had disappeared from both soil and subsoil. Under more favor- 
able temperature conditions it would probably have continued to 
live for some time, notwithstanding the entire absence of free 
moisture, dropping its leaves one by one. Instead of continuing 
to thus drop its leaves until all were gone it had died with a 
dozen still adhering. The temperature in the shade in the open 
air on that day was 110° F.. while the maximum thermometer in 
the greenhouse recorded a temperature of 130° F. That it was 
not the high temperature, independent of the transpiration, which 
killed the plant is evident from the circumstance that various 
other mesquites and acacias, which were in the same greenhouse 
but which were watered daily, remained uninjured. Even two 
milo plants, those in the McOook and Holdrege cylinders, survived 
( pages 91 and 95). 
