"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(N03)2. 

 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 



by withdrawing a preponderating quantity of ions from the seedlings. 

 When the concentration of CaS04 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(N03)2 

 solutions. It is important to note that the concentration of the 

 calcium sulphate solutions at the time of maximum absorption in 



