THE FEMALE REPRODUCTIVE ORGANS. 889 



ane. After the fetus is delivered the contractions of the uterus 

 continue until the placenta also is expelled as the "after-birth." 

 During these latter contractions the fetal blood in the placenta is, 

 for the most part, squeezed into the circulation of the new-born 

 child. The hemorrhage from the walls of the uterus due to the rup- 

 ture of the placenta may be profuse at first, but under normal con- 

 ditions is soon controlled by the firm contraction of the uterine walls. 



The Mammary Glands. At the time of puberty the mam- 

 mary glands increase in size, but this growth is confined mainly 

 to the connective tissue; the true glandular tissue remains rudi- 

 mentary and functionless. At the time of conception the gland- 

 ular tissue is in some way stimulated to growth. Secreting alveoli 

 are formed, and during the latter part of pregnancy they produce 

 an incomplete secretion, scanty in amount, known as colostrum. 

 After delivery the gland evidently is again brought under the 

 influence of special stimuli. It becomes rapidly enlarged and a 

 more abundant secretion is formed. For the first day or two 

 this secretion still has the characteristics of colostrum, but on 

 the third or fourth day the true milk is formed and thereafter is 

 produced abundantly, during the period of lactation, under the in- 

 fluence of the act of milking. If during this period a new con- 

 ception occurs the milk secretion is altered in composition and 

 finally ceases. On the other hand, if the act of nursing is aban- 

 doned permanently the glands after a preliminary stage of turgid- 

 ity undergo retrogressive changes that result in the cessation of 

 secretory activity. The colostrum secretion that occurs during 

 pregnancy and for a day or two after birth differs from milk in 

 its composition and histological structure. It is a thin, yellowish 

 liquid containing a larger percentage of albumin and globulin 

 and a smaller percentage of milk-sugar and fat than normal milk. 

 Under the microscope it shows, in addition to some fat droplets, 

 certain large elements, the colostrum corpuscles.- These con- 

 sist of spherical cells filled with fat droplets, and are most probably 

 leucocytes filled with fat which they have ingested. Colostrum 

 corpuscles may occur in milk whenever the secretion of the gland 

 is interfered with, and their presence may be taken as an indi- 

 cation of an incomplete secretion. 



The Connection Between the Uterus and the Mammary 

 Gland. The physiological connection between the uterus and 

 the mammary gland is shown by the facts mentioned in the pre- 

 ceding paragraph. That the ovary also shares in this influence 

 either directly or through its effect on the uterus is shown by 

 the fact that after complete ovariotomy the mammary gland under- 

 goes atrophy. This undoubted influence of one organ upon the 

 other might be exerted either through the central nervous system 



