50 MEMBRANE PEPMEABILITY AND DRUG ACTLON 



differences in permeability which may exist between the 

 cells of the host and of the parasitic organism. 

 On the second question, as to whether cells differ in 

 their permeabilities, there are two groups of data to be 

 considered: the permeability of a given cell to different 



TABLE IV 



THE PERMEABILITY OF VARIOUS CELLS TO 

 DIFFERENT SUBSTANCES 



substances and the permeability of different cells to the 

 same substance. Table iii indicates very wide differences 

 in permeability of the cells of Chara to different pene- 

 trating substances. It will be seen that the rate of per- 

 meation of the substances studied varies by a factor of 

 10*. But the range of permeabilities to different sub- 

 stances is in fact even greater than this, for it is incon- 

 venient to study the substances which penetrate ex- 



