58 E. J. STIEGLITZ 



swelling of colloid membranes as do the univalent ions and that 

 this effect is primarily a surface one. It is his belief that any 

 diffusion of electrolytes depends not only upon the osmotic 

 pressure, but also upon the 'salt effect' upon the surface of the 

 proteins on the membrane. Fischer (18, p. 51) states that iron 

 (ferric) is the most effective electrolytic basic radical inhibiting 

 the swelling of fibrin in water and acid. This is said to be 

 equally true for other proteins. Calcium is considerably less 

 effective in this connection, but among the acid radicals the 

 citrate is the strongest. As both ferric and citrate ions are 

 present during the period of secretion of such substances 

 as phenolsulphonephthalein, carbonate, and probably calcium, 

 they are directly associated with changes in the colloidal condi- 

 tion of the cytoplasm of the secretory cells. This effect is 

 directly proportional to the concentration of the ions up to 

 certain limits, an observation coinciding with the fact that with 

 decreasing iron concentration the cloudy carbonates of calcium 

 may gradually reappear in the urine before it is completely free 

 of the ferric radical. 



Assuming the Fischer theory of the physicochemical nature of 

 water absorption, retention, and secretion by tissues on a basis 

 of changes in the cell colloids (18, pp. 151 to 171), and realizing 

 that the different parts of a single cell contain colloids of differ- 

 ent natures, we find it is possible to explain the inequalities in 

 water content (and similarly, salt content) of different parts of 

 the same cell. An example of such inequalities is the accumula- 

 tion of iron under the brush border in the first series. Fischer 

 states (18, p. 165): " Concentration differences can be main- 

 tained in different parts of the same cell, between different cells 

 or between cells and their surrounding media even in the absence 

 of 'membranes' because of inequalities in distribution, deter- 

 mined by solubility, adsorption or chemical differences, or all 

 three together." Meyer (67) and Overton (68) have pointed 

 out that the rate of adsorption of substances by a cell is depend- 

 ent upon the relative solubility in water and lipoids, or, in other 

 words, upon its partition coefficient, and in the same way this 

 controls the intracellular distribution. The adsorptive power 



