MEMBRANE CHANGES DURING STIMULATION 377 



tion of semi-permeability is a universal effect of poisoning 

 with chloroform or similar substances; this effect is seen 

 in the wilting of turgid plant tissues, increase of electrical 

 conductivity, or diffusion of substances (e.g., coloring 

 materials) from the cells. The leaves of the common 

 false indigo plant, which blacken on death, also afford a 

 striking demonstration.^ If the leaves are poisoned with 

 chloroform in the absence of oxygen (e.g., in a gas 

 chamber with hydrogen) , they remain green ; if they are 

 then exposed to air they blacken immediately. When 

 Hving, intact leaves are exposed to oxygen at 100 atmos- 

 pheres, no blackening results. On the other hand, 

 mechanical injury, natural death, or poisoning all 

 produce this effect at air tension. The essential condi- 

 tion for the reaction is apparently the destruction of 

 diffusion-preventing partitions which during life keep 

 the interacting substances apart. According to Chiari,^ 

 autolysis of animal tissues is similarly hastened by ether 

 or chloroform. It thus seems probable that in many if 

 not all cells the external layer of protoplasm (plasma 

 membrane) is not the only semi-permeable structure 

 present, but that it is continuous with a system of 

 similarly constituted films pervading the protoplasmic 

 system and determining the spatial distribution of the 

 water-soluble cell-constituents.^ 



If a temporary breakdown of film-structure can 

 determine chemical effects of this kind, the possibility 

 presents itself that in cells of a different type of organiza- 

 tion, e.g., muscle cells, other chemical reactions, including 



^ Cf. Harvey, loc. cit. 



2 Chiari, Arch, exper. Path. u. Pharmakol., LX (1909), 256. 



3 Compare Hofmeister's Chemische Organisation der Zelle. 



