268 INTERNAL SECRETIONS 



does not take place until the ovary has initiated the whole 

 chain of changes. 



We have seen also that there is no reason for assuming any 

 essential differences between the corpora lutea graviditatis 

 and those corpora lutea which are periodically formed after 

 ovulation. There is in both cases a formation of luteal cells, 

 the number of which is merely greater in the first case. As 

 already remarked, the attachment of the ovum evidently 

 produces a longer persistence and a greater development of 

 the corpus luteum than is possible in connection merely with 

 menstruation. 



We have seen further that the premenstrual changes in the 

 uterine mucosa resemble those of early pregnancy. 



In view of these considerations it seems justifiable to regard 

 the changes which occur in the organism during pregnancy as 

 a further link in the chain of changes which begin in the 

 organism at the time of sexual maturation. Every menstruation 

 and every pregnancy are really of the nature of a repeated and 

 highly intensified sexual maturation. If the first corpus luteum 

 menstruationis can be called a "puberty gland" in a narrower 

 sense of the term as causing sexual maturation or puberty, all 

 the subsequent corpora lutea menstruationis and all the corpora 

 lutea graviditatis are nothing else than parts of this puberty 

 gland. 



Just as we have compared all the changes occurring in 

 menstruation, heat and pregnancy with those which take place 

 at the time of sexual maturation or puberty in the narrow 

 sense, so in the same way we may compare with the latter the 

 different stages of development preceding sexual maturation. 

 There is indeed at the time of puberty no process which is 

 essentially new to the organism. There is in reality only an 

 extraordinary acceleration of processes which were going on 

 up to this time at a slow rate. This would be true even for an 

 animal like the male rabbit, where there is possibly no internal 

 secretion produced by the gonad between birth and early 

 puberty. Furthermore, the formation of the first corpus 

 luteum is not an essentially new process, since we have seen 

 that there is no real difference as to fimction between atretic 

 follicles and interstitial tissue arising from them on the one 

 hand, and corpora lutea on the other. The first and all the 

 following corpora lutea menstruationis and all the corpora 



