AUGUST 19, 1921 ALSBERG : PHYSIOLOGICAL CHEMISTRY 327 



plasmolyze. A study of the plasmolyzing power of many hundreds of 

 substances has shown that substances of the most diverse chemical 

 character can enter cells readily. They have neither molecules of 

 similar size, nor similar melting points nor similar boiling points, nor 

 similar chemical affinities. They have one property in common; 

 they are more freely soluble in fatty oils and lipoids than in water. 

 If any of these substances be mixed with water and oil, much of the 

 substance will dissolve in the oil and relatively little in the water. As 

 the physicist would put it, the distribution coefficient for these 

 substances between oil and water is greatly in favor of oil.^^ 



A very good illustration of this phenomenon is furnished by glycerin 

 and its derivatives, mono- and dichlorhydrin.^' Glycerin enters cells 

 very slowly, monochlorhydrin quite rapidly and dichlorhydrin almost 

 instantaneously. Glycerin has no narcotic action, monochlorhydrin 

 has a fairly strong narcotic action and dichlorhydrin quite a powerful 

 narcotic action. In the days of the purely chemical conception of 

 protoplasm, it would have been assumed that chlorine was a "toxo- 

 phore" group, ^^ that perhaps its action depended upon its electro- 

 negative character or that mono- and dichlorhydrin had greater 

 affinity for the cell-substance. The fact is that glycerin is but slightly 

 soluble in oil and very soluble in water while its chlorine derivatives 

 are very much more soluble in oils than in water. ^^ 



Since so many substances that pass readily through the semi-per- 

 meable cell membranes are oil-soluble, many biologists have concluded 

 that the cell membrane is, in part at any rate, composed of fat-like 

 substances, probably lipoids, like lecithin and cholesterin. This in- 

 ference is based on the fact that it has been shown for a great variety 

 of semi-permeable membranes that they permit only those substances 

 to pass through them that are soluble in them. Thus chloroform, but 

 not alcohol, may be made to pass through rubber membranes. Hence 

 it was inferred that since only fat-soluble substances pass readily 

 through the semi-permeable membranes of cells, these membranes 

 must consist, in part at any rate, of fats or fat-like substances such as 



" E. Overton. Studien. ueber die Narkose. (Jena, 1901.) H. Meyer. Arch. exp. 

 Path. Pharm. 42: 109. 1899; 46: 338. 1901. P. Ehrlich. Therap. Monatsh., March, 1887. 



1' E. Overton. Ueber die allgemeine osmottsche Eigenschaften der Zelle. Vierteljahrb. 

 Naturforscherges. Zurich 44: 889. 1899. 



i« C. R. Marshall and H. L. Heath. The pharmacology of the chlorhydrins , 

 a contribution to the study of the relations between chemical constitution and pharmacological 

 action. Journ. Physiol. 22: 1, 2. 1897. 



1" H. KioNKA. Zur Theorieder Narkose. Arch. Int. Pharmacodynamie et Therapie 7. 



