v GENEEATIVE SYSTEM OF THE FEMALE 171 



fertilisation has not taken place, or after the fifth to sixth month if 

 pregnancy followed, the development of the corpus luteum ceases 

 and the involution begins, in the first case (corpus luteum spurium) 

 rapidly, in the second (corpus luteum verum) much more slowly, so 

 that it is recognisable even at the time of parturition. 



The retrogression of the corpus luteum manifests itself by a 

 diminution in size and a progressive increase of consistence, by 

 which it is converted into a little fibrous nodule, or into a body of 

 hyaline appearance, which is called the corpus- fibrosum albicans 

 (Fig. 57). This occurs owing to the degeneration and reabsorption 

 of the lutein cells, and the simultaneous organisation of the central 

 gelatinous tissue into dense fibrous tissue. Finally, the simple 

 fibrous nodules and the corpora fibrosa albicantia gradually dis- 

 appear owing to hyaline degeneration, and there remains of them 



FIG. 56. Cortical part of a corpus Ititeum of woman in fifth week of pregnancy. Highly 

 magnified. (Hans Rabl.) L, lutein cells ; Ti, theca interna with hypertrophic cells. 



only a cicatricial contraction by which as we have said the 

 surface of the ovary is made always more irregular with age. 



II. With ovulation is initiated in woman the period of puberty, 

 which in our temperate climate occurs at 13 to 15 years of age. 

 It manifests itself by a new phenomenon, the sanguineous flow 

 from the vulva, which is called menstruation (catamenial flux or 

 monthly periods) ; we shall examine this process and its internal 

 causes. Puberty is shown also by a number of metamorphoses 

 which affect the development and the functions of the entire 

 organism. The larynx develops and the voice loses its sharpest 

 notes, but in compensation acquires greater intensity ; the circum- 

 ference of the thorax increases, and the pelvis enlarges ; the sub- 

 cutaneous layer of adipose tissue becomes thicker; the nipples 

 protrude ; hairs appear on the pudendum and in the axillae ; the 

 psychical character is modified, becoming more reserved and 

 modest ; in fact, the whole generative system, external and 



