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These experiments give us some idea as to what percentage of the 
rainfall remains in the soil for the use of the plant in the case of 
large and small rains, but do not quite answer the question how one 
and the same quantity of rain is utilized in moistening the earth 
when it is distributed through a larger or smaller number of rainy 
days. 
On this latter question Wollny has made the following experi- 
ment: A quantity of water corresponding to a rainfall of 60 muilli- 
meters was communicated to an experimental tub, No. 1, all at once, 
while in tub No. 2, 30 millimeters were given the first time and the 
remaining 30 after three days; in the third tub 20 millimeters were 
given at first and 20 millimeters every other day thereafter, and, 
finally, in the fourth tub, 10 millimeters were given every day, so 
that in six days all had received the same quantity of water. These 
experiments were repeated for different kinds of soil and the results 
show that in all cases the quantity of water lost by evaporation is 
larger the more frequently the water was communicated or the greater 
the number of rainy days. A fine illustration of the truth of this 
principle as apphed to practice is narrated by Haberlandt, who found 
that in 1874 the farmers at Postelberg got much better crops than 
those at Lobositz, which could only be attributed to the fact that 
during that year Postelberg had received 246 millimeters of rain- 
fall in forty days, or an average of 6, whereas Lobositz had received 
309 millimeters in seventy-seven days, an average of 4, so that the 
usefulness of the greater quantity of rain in Lobositz did not equal 
that of the smaller quantity at Postelberg. 
Wollny shows that since the period of the heaviest rainfall occurs 
throughout central Europe at the time of the largest evaporation 
from the soil we must conclude that for the naked earth the wetting 
of the soil during the warmer season of the year is controlled much 
more largely by the rainfall than by the evaporation depending, on 
the temperature. His observations with the lysimeter show that the 
precipitation is principally concerned in the moistening of the naked 
soul during the warmer season, while the influence of the temperature 
and the resulting evaporation nearly disappears and is only observ- 
able in periods that are deficient in rain. In most cases the vegeta- 
tion is injured when the atmospheric precipitation during the coldest 
season of the year is insufficient. The precipitation at this time of 
the year is therefore quite as important for the success of the harvest 
as that which falls during the period of vegetation. (Wollny’s 
Forschungen, Vol. XIV, pp. 138-161.) 
A. Seignette has shown that the law of levels propounded by 
Royer is confirmed. This law states that for given plants and for 
other uniform conditions the reserve nutriment in the earth is always 
found at a constant distance below the surface; thus the bulbs of 
