484 PROCEEDINGS OP THE AMERICAN ACADKMY. 



Of physico-chemical phenomena we have, assuming the permeability of 

 the cell to water, the loss of water from the cell to the solution outside 

 of it, because its osmotic concentration within the cell is in excess of that 

 outside. This process will take place both in the application of the four 

 salts and of milk sugar, but with a very probable difference in degree, 

 depending upon a difference in permeability of the cell to the two kinds 

 of substances. Milk sugar belongs to a class of substances, the sugars in 

 general, found to have very low, if any, power of permeation. Upon the 

 other hand the physiological salts, and especially ionic constituents of 

 them, have been found by Hamburger and others to have more or less 

 power to permeate cells. We now have a better knowledge of the per- 

 meability of the mammalian blood-corjiuscle than of any other free 

 animal cell. Although the subject of its permeability with reference to 

 particular substances, especially electro-negative radicals (ions) of salts, 

 has been much in dispute, certain results are now established with con- 

 siderable certainty. These are well summarized in tabular form by 

 Hamburger (:02, p. 260). As the results — thus far much too meagre 

 in proportion to the importance of the subject — upon different cells 

 accumulate, it becomes evident that among different kinds of cells much 

 similarity exists in regard to the permeating power of such classes of sub- 

 stances as sugars, alkali salts, and possibly alkali earths. This makes the 

 conclusions above stated regarding the permeating power of milk sugar 

 and the four salts, as well as the quantitative difference between the two, 

 in the case of Stentor extremely probable. The experimental evidence 

 which 1 have thus far worked out, as described in the section on Per- 

 meability (p. 503), is very limited, but such as it is it coincides with the 

 results found in other cells. 



Returning from this necessary digression to the case of Stentor in 

 hyperisotonic media, we would have a higher osmotic concentration of 

 milk sugar and of single salts, respectively, outside the cells than inside 

 them. Granted non-permeability in the former case, and a certain 

 degree of permeability in the latter, more water would be abstracted 

 fj om the cells by milk sugar then by the salts. For the inward move- 

 ment of the salts or their ions would tend to establish as high osmotic 

 concentration of these salts within the cell as existed outside of it. This 

 process of equilibration would be absent from the cells in milk sugar. 

 We may now answer with much probability of correctness the following 

 important question. In the total destructive effect produced by the appli- 

 cation of hyperisotonic concentrations of these four salts respectively, is 

 the abstraction of water, i. e., the simple osmotic factor, of determining 



