228 INJURY, EECOVEEY, AND DEATH 



forming wrinkles. What part these films or membranes 

 play in permeability is not known. 



When a cell is crushed, so that drops of protoplasm 

 are extruded, it is often observed that each drop behaves 

 as if surrounded with a plasma membrane, and a rupture 

 is in most cases instantly repaired (as long as the cell 

 remains in the normal condition). This might be ex- 

 plained as due to the formation of films upon contact 

 with liquid. 



Kuster (1909; 1910 A, B.) found that when the proto- 

 plasm of a cell was separated into several pieces by 

 plasmolysis the parts would fuse if brought together at 

 once, but if left for a time would no longer do so, indicat- 

 ing that a change had taken place in the surface film. 



Kite (1913) states that a dye which could not pene- 

 trate the cell was able to spread freely in its interior, 

 when introduced by a Barber pipette.*® 



The nature of the cell surface has been the subject of 

 much dispute. Overton based his view that it is lipoid 

 in nature on the ground that lipoid-soluble substances 

 readily penetrate, while those which are not soluble in 

 lipoid do not enter the cell, and stated that this was 

 particularly the case with inorganic salts. It was subse- 

 quently found, however, that cells are permeable to salts,^' 

 and to other substances insoluble in lipoid. He found^' 

 an apparent confirmation of his theory in the behavior of 

 dyes. It had been shown by Ehrlich^^ that basic dyes are 

 taken up by nerves and by lipoid substances. Overton 

 extended this notion to living cells in general and assumed 



"(7/. Pfeffer (1900) 1:107. 

 " See page 203. 

 ° Overton (1900, 1902). 

 "^Ehrlich (1893). 



