TRUE & HARVEY: ABSORPTION OF CALCIUM SALTS 507 
A glance at the curves shows that in some respects the course of 
absorption is markedly different from that seen in the case of Ca( NOg)o. 
Alike in the distilled water control and in the solutions originally 
containing 11.08 and 15.6 grm. norm. respectively, the solutions gain 
ions and not even at the time of greatest absorption are the plants able 
to reduce the ion concentration to that seen at the beginning of the 
experiment. These quantities of the salt in question are insufficient 
to prevent the solutions from acting practically like distilled water 
HO, 550 
00 + 900 
850 850 
G0 B00 
750 
V 
[A 
a 
NORMAL CONCENTRATION X 106 
BS 
Y 
[| 
| 
LIAS 
58 — 
g 
OLAS 12 13) G14 a da ae 
DAYS 
Fic. 2. For explanation see text. 
by withdrawing a preponderating quantity of ions from the seedlings. 
When the concentration of CaSO, reaches about 30 grm. norm. in a 
million liters, an equilibrium of some sort seems to be established 
between the plant and the medium with the result that neither ab- 
sorption nor leach is marked. A similar equilibrium point appears 
at approximately the same concentration in the case of Ca(NOs)2 
solutions. It is important to note that the concentration of the 
calcium sulphate solutions at the time of maximum absorption in 
