$8 Stiidies of Diffusion through Rubber Membranes [Sept. 



was inaugiirated we also saw a late reference to the well-known 

 fact, regarding the swelling of rubber in lipin solvents, on which our 

 work was based.*^ Ten months later we demonstrated these findings 

 at a meeting of the American Society of Biological Chemists (see 

 page 64). 



The succeeding sections of this paper present reprinted prelim- 

 inary reports on various portions of the studies which thus far have 

 developed from the observations described above. It is my Inten- 

 tion to discuss in detail each seotion of the work, and additional ex- 

 periments, at the earliest opportunity, when I hope to dwell more 

 particularly on the significance of such results for the Student of the 

 functions of cell membranes, and for the investigator of the co- 

 ordinations and equilibria in intracellular affairs. 



IL ON THE DIFFUSIBILITY OF BIOLOGICAL SUBSTANCES 



THROUGH RUBBER' 



The writer and his associates have f ound that many ether-soluble 

 substances of biological origin, such as fat and cholesterol, pass 

 readily from ether Solutions through rubber membranes into ether 

 when the mechanical conditions for such diffusions are favorable. 

 Lecithans appear to be wholly indiffusible. 



Many substances which are soluble in fatty oils, Chloroform, al- 

 cohol, acetone, ethyl acetate, and other solvents of similar powers, 

 or in mixtures of such solvents, promptly diffuse through rubber 

 under suitable conditions. Collodion is one of the products which 

 appears to be indiffusible under such circumstances. When an ordi- 

 nary ethereal Solution of collodion (containing 24 per cent. of alco- 

 hol) is dialyzed in a rubber Condom against ether in a closed vessel, 

 the alcohol rapidly passes to the exterior and the collodion gradually 

 gelatinizes. Liquid accumulates in the bag under these conditions. 



Various inorganic substances diffuse through rubber under the 



found to diffuse from benzene through a rubber membrane into benzene; and 

 camphor diffused from pyridin, alcohol, and toluol through rubber membranes 

 into the same solvents, respectively. A recent study of Kahlenberg's paper in the 

 original makes it evident that our results may be explained on the theory of 

 diffusion which Kahlenberg has done much to render convincing. 



'Flack and Hill: Journal of Physiology, 1910, xl, p. xxxiii. 



' Gies : Proceedings of the Biological Section of the American Chemical 

 Society: Science, 1911, xxxiv, p. 223; Biochemical Bulletin, 1911, i, p. 125. 



