THE PROTOPLASMATIC MEMBRANE 



membrane as are soluble in fat. This is the reason 

 why chloroform and ether are so readily taken up 

 by the cell. Overton showed further that the 

 phenomenon of narcosis is principally founded 

 upon the storing of chloroform by the fatty com- 

 pounds which are most important constituents 

 in the nervous system. Overton's theory was at 

 last confirmed by experiments on aniline dyes. 

 These substances as a rule are soluble only in 

 alcohol or in such organic liquids as dissolve fatty 

 compounds. They are readily taken up by cells. 

 It is easy to prepare from such colouring matters 

 compounds which are soluble in water. This is 

 done by treating them with sulphuric acid. The 

 sulphonic acids thus obtained are substances 

 soluble in water, but insoluble in ether or alcohol. 

 Such solutions cannot enter living cells. 



The conclusion finally drawn by Overton from 

 all these facts was this, that protoplasm is en- 

 veloped in a thin layer which is either rich in fatty 

 substances or is a thin film of fat or oil, as was the 

 opinion expressed by the German physicist 

 Quincke some years before Overton's work 

 appeared. 



There are many facts, indeed, which seem to 

 make such a theory very plausible. Living 

 protoplasm always acts as liquids do in a state of 

 equilibrium. When it enters a state of rest it 

 assumes the shape of a sphere. Such action can 

 be quite distinctly seen in amceba when they are 

 39 



