ESTRANE 



This means the same as the complete formula above. When- 

 ever, in formulas cited hereafter, a linkage point is written 

 without indication of the elements, it means a carbon atom 

 with enough hydrogen atoms to fill up its quota of 4 valences. 

 Unsaturated carbon atoms will be indicated by double bonds. 



The relation of estrane to simpler organic compounds. 

 Those substances derived from estrane which are of interest 

 to us as hormones belong to a group of compounds called 

 sterols, which have already been characterized briefly in 

 Chapter IV. The relation of the sterols to more familiar sub- 

 stances can be explained as follows : 



Three benzene rings condensed in line form the substance 

 anthracene : 



ANTHRACENE 



In a slightly different arrangement, exactly the same atoms 

 constitute phenanthrene : 



{ ^i5 } 



