Penetration into Cells 



385 



Dead cells behave somewhat like living ones. In the case 

 of acids of the first class, free C0 2 could be detected as in living 

 cells : while acids of the second class penetrated dead cells at 

 about the same rate and in apparently the same manner with 

 reference to C0 2 liberation as in living cells. 



The rate of penetration of an acid depends therefor upon the 

 nature of the acid used. Previous investigators have neglected 

 the fact that carbonate decomposition would delay changes in 

 the H ion concentration of the cell; and have therefore been mis- 

 led as to the rates of penetration of acids of the first class. 



II 



Plants were also placed in sea water containing the following : 

 (1) enough C0 2 to make the P H 7.2; (2) KHC0 3 , .03M; (3) 

 NaHC0 3 , .03M; the P H of the last two solutions was 7.8. 

 In all three cases free C0 2 accumulated rapidly in the 

 sap, the P H of which first became about 5.2 but later slowly 

 increased and ultimately exceeded the normal. The P H of 

 sap from which the free C0 2 had been blown out was ob- 

 served to have increased; and the longer the cells remained 

 in the solution the more alkaline the C0 2 -free sap became until 

 finally a P H of 8.6 had been reached. This process was quicker 

 in the case of KHC0 3 than in that of NaHCO s , possibly be- 

 cause K' penetrates more rapidly than Na'. The known prepon- 

 derence of K' in the cell-sap of Valonia may be in part due to 

 such selective permeability. When NaCl, KC1 or KN0 3 were 

 dissolved in sea water in the same concentration (.03 M) no 

 such changes in P H were noted. They are therefore character- 

 istic effects of the penetration of HCO s ' into the cell. Details 

 of this study will appear in a later journal. 



