THE HORMONES IN HUMAN REPRODUCTION 



be derived from progesterone and from nothing else been 

 found in the urine. Either it escapes from the body, in lower 

 animals than man, in some elusive form ; or it is broken down 

 so completely that its chemical fragments are undistinguish- 

 able among the simple remnants of bodily chemicals that make 

 up the excretions (Appendix II, note 6). 



Action of progesterone on the muscle of the uterus. In 

 1927 a well-known Austrian scientist, Hermann Knaus, dis- 



Fio. 17. Arrangement of apparatus for maintaining excised pieces of 

 uterine muscle under physiological conditions and recording its con- 

 tractions. 



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