36 ABSORPTION AND EXCRETION OF SALTS BY ROO’ 
concentration for each salt or mixture of salts at which of 
peas absorb and excrete electrolytes at the same rate; (2) that if a 
culture solution is initially less concentrated than this equilibrium 
concentration, excretion from the roots overbalances absorption; 
(3) that if a solution is initially more concentrated than this equi- 
librium, absorption overbalances excretion; (4) that absorption 
from solutions initially above equilibrium concentration may carry 
them far below this concentration; (5) that the extent to which pea 
roots can carry the concentration of a solution below equilibrium 
concentration depends upon the ratio of magnesium to calcium; (6) 
that the molecular ratio which favors maximum absorption is 
: (7) that the ratio of magnesium to calcium which insures good 
development of pea roots is : if the solutions are so concentrated 
that their magnesium content alone would inhibit the development 
of lateral roots; but (8) that this ratio is nearer = if the solutions 
are so dilute that the magnesium content alone would not inhibit 
the development of lateral roots. 
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