EFFECT OF MICELLE FORMATION 39 



general capacity to promote cell division. Very much 

 more remains to be done, however, before these results 

 of ScHULMAN and Rideal can be adequately claimed to 

 be linked with physiology. 



The Effect of Micelle Formation 



In aqueous solution, when the properties of a solute are 

 dominated by its polar groups, as is the case with methyl 

 alcohol, the solute molecules are dispersed mainly as 

 single molecules. But when there is a great excess of non- 

 polar hydrocarbon groups in the molecule, practically 

 speaking no single molecules exist in an aqueous solu- 

 tion of the substance concerned. Instead, the molecules 

 are organised so that the non-polar parts are tucked 

 away into micelles, which may be spherical or take the 

 form of bimolecular sheets. The polar groups of the 

 molecules are mainly to be found in the interface with 

 the water, so that the non-polar part of the molecules 

 does not in fact necessarily come into direct contact 

 with water molecules. Substances forming solutions of 

 this type are stearic acid, cholesterol and tripalmitin. 



Where there is a balance between polar and non-polar 



+ 

 groups, as in CH3(CH2)9 N Mcg, there is an equilibri- 

 um between single molecules and micelles, which is 

 quite dynamic. If the surface tension of such a solution 

 is studied as a function of concentration it is found that 

 as the concentration is increased, at first the surface 



