20 BOTANICAL GAZETTE [JANUARY 
of growth, as the solution strength, with which the soil is moistened, 
decreases. Normal growth is reached at about 2m/1000. Between 
the point at which no growth takes place and where normal growth 
Fic. 1.—Copper sulfate series in soil. Aug. 24-30. 1905. 
may be attained, we will, for convenience, call the tension line or line 
of stress. It means that region of concentration in which a struggle 
for life is apparent. In jig. 2, which is a photograph of the same 
series 12 days old arranged in opposite direction, it will be noted 
Fic. 2.—Copper sulfate series in soil. Aug. 24-Sept. 26. 1905. 
that 2/1000 to n/2500 has grown more than the control. Also that 
n/100 and gn/t000, which were growing in fig. 1, are now dead. It 
thus. shows that during the first six days the seedling was able to 
endure a higher concentration than afterward; and further, that 
acceleration does not 
occur until after the 
reserve food of the seed 
has been exhausted. 
The solution series 
represented in fig. 3 had 
concentrations from left 
Fic. Pini sulfate series in solution. 
Aug. 22-30. 1905 to right as follows: 
gn/ 1000, 8n/1000, 
7n/toce, 6n/1000, 5/1000, 4n/1000, 3n/1000, 2n/1000, n/1000, 
n/2500, n/5000, n/7500, n/10000, control. In this series no 
