500 Mr. W. Stiles and Dr. F. Kidd. The Comparative 



Table X. — Absorption of Aluminium (Data from Pantanelli). 



* 



Plant organ. 



Salt. 



Concentration. 



Ratio of equivalents 



£ kation , , , 



absorDeci 



anion 



Azolla 



Al(Jf03)3 

 A1(N03)3 

 Alj(S0,)3 



A1,(S04)3 



Als(S0,)3 



-0125 M 

 -0125 M 

 -0120 11 

 -0120 M 

 0-OoM 



1 -008 



1 -570 



2 -5.33 

 8 -513 

 3-681 



As a consequence of this great inequalit}' of absorption, we should expect 

 either an exosmosis of a kation from the tis.sue, or the replacement of the 

 aluminium ion by hydrogen ion from the solvent, the corresponding quantity 

 of hydroxyl ion being absorbed with the aluminium. In the latter case the 

 solution would become acid, and this is indeed the case, as we have ourselves 

 observed. As the mobility of the hydrogen ion is so much greater than that 

 of other kations, the increase of conductivity of the external solution without 

 exosmosis into it is at once explained. 



The results of Pantanelli summarised above also show that with aluminium 

 nitrate the absorption of the aluminium and nitrate is more equal. This 

 agrees with the results obtained by us, for with aluminium nitrate there is 

 no rise in conductivity of the external solution, but a progressive decrease as 

 in the case of salts of the alkali metals. 



With those harmless salts which show in our experiments with carrot a 

 progressive decrease in conductivity, it seems reasonable to conclude, there- 

 fore, that the excess of absorption of one ion over the other is much less than 

 in the case of aluminium nitrate. Moreover, in each series all the salts 

 employed had a common ion, and it is reasonable to suppose, therefore, that in 

 any one series the order in which the differing ions are absorbed is given by 

 the order in which the conductivities of the external solutions are lowered. 



"We have shown in the part of this paper dealing with the results of 

 experiments that the initial order of intake of the ions is not necessarily the 

 same as the final order. This, for instance, is especially noteworthy in the 

 case of the sulphate ion, which appears to be absorbed more rapidly in the 

 beginning than the nitrate or chloride ion, but of which the total quantity 

 absorbed is considerably less than in the case of these monovalent anions. 



The initial order of absorption of kations as indicated by our experiments 

 is as follows : K, [Ca, Na], Li, Mg, Zn, Al ; it is possible the positions of Ca 

 and Na should be reversed. The final order is, however, the following 

 K, Na, Li, [Ca, Mg], the chief difference being in the position of calcium 



