38 



ACTIONS OF DRUGS ON SURFACES 



a theory where there is an interesting correlation be- 

 tween a complex physiological effect and a simple phys- 

 ico-chemical phenomenon. As Dale has pointed out, 

 this coincidence cannot be a sufficient explanation of the 



Minutes 



Fig. 7. The relationship between reduction of surface potential of pro- 

 tein monolayers and oestrogenic activity in the stilbene series, a. 4,4' 

 dihydroxy stilbene (i : 150); b. 4,4' dihydroxy dimethyl stilbene 

 (i : 40,000) ;c. 4,4' dihydroxy ethyl stilbene ( I : 5,000) ;d. 4,4' dihydroxy 

 ethyl methyl stilbene (i : 1,000,000); e. 4,4' diethyl stilbene (i : 

 3,000,000); f. 4,4' dihydroxy he xadienediphenyl( I : 2,500,000) ;g. 4,4' 

 dihydroxy dipropyl stilbene (i : 100,000). The reduction in surface 

 potential increases steadily from a — f : substances e and f, which have 

 the maximum oestrogenic activity, also combine most readily with the 

 protein film. Substance g replades the protein film. 



physiological action of oestrogens in producing oestrus, 

 for this change is restricted to certain types of cells of 

 the body, whereas all cells are lavishly provided with 

 protein monolayers. It is not, however, beyond the 

 bounds of possibility that the action of oestrogens on 

 monolayers is the basis, or part of the basis, of their 



