RECORD OF THE EXPERIMENTS. 13 
PLAN OF THE EXPERIMENTS. 
Three preliminary experiments were carried through before making 
any conductivity measurements, in order to become acquainted with 
the specific reactions of pea roots to solutions of magnesium and cal- 
cium nitrates. In each of the first two experiments a series of 14 
solutions was used. 
Fic. 6.—Seedlings of culture 12, experiment C, 
EXPERIMENT A. 
= 
5,000 
M ; 
alent concentration at 500° No. 2 was pure magnesium nitrate, No. 
3 was nine-tenths magnesium nitrate and one-tenth calcium nitrate, 
No. 4 eight-tenths magnesium nitrate and two-tenths calcium nitrate, 
etc. Thus each of the 11 cultures of equivalent concentration dif- 
231 
No. 1 was agnesium nitrate. Nos. 2 to 12 were all of equiv- 
