(o) 



J. F. DANIELLI 



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^mm 



-* Polar side-chain 



Non-polar side-chain 



(b) 



<imwg» 



Lipoid molecule 



Protein molecule 



"Polar pore 



Figure i. (a) Diagram of protein molecule; (b) Diagram of pore of membrane. 



experiment, that only a small fraction of the total surface area is involved in permit- 

 ting the abnormally high rate of penetration of these exceptional substances. 



Recently the work of Collander (1949), of Jacobs (1952) and of Ussing and Zeuthen 

 (this symposium) has shown that very small molecules, such as methyl alcohol, 



