APPENDIX I 



scores and hundreds of new synthetic compounds of similar 

 constitution. 



To proceed from cyclopentenophenanthrene to estrane, the 

 hydrocarbon first mentioned above, let us imagine the former 

 compound completely saturated with hydrogen and a methyl 

 group (CH3) attached to the carbon atom which we have 

 numbered 13: 



ESTRANE 

 If the first ring is unsaturated, we have estratriene : 



ESTRATRIENE 



The estrogenic hormones. At last we have arrived at an 

 actual hormone, for the best-known of all the estrogenic sub- 

 stances, estrone^ is like estratriene except that it has a hy- 



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