CONTENTS 



interaction between the ovaries and the pituitary gland. 

 Menstruation a periodic breakdown of the uterine lining 

 (endometrium) when the corpus luteum retrogresses. 

 Occurrence, however, of anovulatory cycles, without a 

 corpus luteum, and without "premenstrual" changes. Ex- 

 planation of the bleeding as due to shutting oflf of the 

 coiled arteries of the endometrium caused by deprivation 

 of estrogenic hormone or of progesterone; bleeding due 

 to progesterone deprivation believed to be a special case 

 of estrin-deprivation bleeding. Theory of the menstrual 

 cycle based on these ideas. The significance of menstrua- 

 tion unknown. 



CHAPTER VII. ENDOCRINE ARITHMETIC 179 



Calculation of the quantities of the two hormones pro- 

 duced in the ovaries and the rate at which they are se- 

 creted; in the case of the corpus luteum, discussion of 

 such questions as the amount of hormone made by a 

 single cell, the amount made by the whole gland in one 

 day, and divers other matters of interest concerning the 

 quantitative aspect of ovarian function. 



CHAPTER VIII. THE HORMONES IN PREGNANCY 199 



The maintenance of pregnancy a complex a£fair, de- 

 pendent partly on the hormones. The placenta as a source 

 of gonadotrophic and estrogenic hormones ; progesterone 

 also apparently made by the human placenta. Lactation 

 induced by a special hormone of the pituitary gland. 



CHAPTER rx. THE MALE HORMONE 217 



The testis constructed of tubules in which the sperm 

 cells are made; the interstitial cells. The seminal ducts, 



{ aru } 



