44 ACTIONS OF DRUGS ON SURFACES 



loidal solution molecules may be oriented parallel to 

 one another by long-range forces. More recently 

 ROTHEN has obtained results which can be interpreted 

 to mean that relatively specific forces, such as those be- 

 tween antibodies and antigens, may extend over a dis- 

 tance of at least loo A.U. The biologist is tempted by 

 such phenomena as the adlineation of chromosomes in 

 meiosis, and the reaction of cells to one another, to pos- 

 tulate similar forces extending up to several microns. If 

 the field of action of these forces is as extended as some 

 suppose, then they must be of fundamental importance 

 in such phenomena as differentiation, chromosome 

 mechanics, fibre adlineation and enzyme action. From 

 the scanty information which is available it is already 

 clear that the operation and the specificity of these for- 

 ces is greatly affected by the net charge on the molecules 

 concerned, and also by its detailed distribution. It is 

 therefore plain that we have here a fertile field for the 

 study of the action of drugs. But our knowledge is at 

 present so restricted that it is not possible to do more 

 than indicate the immense possibilities which exist here 

 for future research. 



