INDICATIONS OF CONCEPTION. 533 



the liver emerges as a thickened deposit of cells, into which the wall of 

 the intestine bulges so as to form a kind of sac, and from this rudiment 

 a ramified structure arises, which at last recedes from its place of origin, 

 and is connected with the intestine by the hepatic duct. The commence- 

 ment of this structure is about the third week, but it proceeds with so 

 much rapidity that in the third month it nearly fills the abdominal cav- 

 ity. The functions of the liver at this period have already been pointed 

 out, the meconium it secretes being modified bile (page 202). In like 

 manner, from the digestive tract, the pancreas and salivary glands orig- 

 inate from masses of cells, ducts being formed by deliquescence of por- 

 tions within. From the alimentary canal, also by budding and deliques- 

 cence, the lungs arise, their cavity communicating at first by several aper- 

 tures with the pharynx. This occurs about the sixth week. These organs 

 are gradually removed from the place of origin, as in the case of the liver. 



The Wolffian bodies are temporary urinary organs, which precede the 

 kidneys and eventually disappear. They are of an ovoid The Wolffian 

 shape, and consist of a duct from which transverse canals todies. 

 branch forth, the duct discharging into the sinus urogenitalis. They 

 originate about the end of the first month, and commence to degenerate 

 in the third. In fishes they remain as the permanent urinary apparatus. 

 The testes or ovaries arise from the inner margin of the Wolffian body, 

 the former being guided into the scrotum by the gubernaculum. This 

 descent commences between the fourth and fifth month, and is completed 

 at birth or shortly after. 



Among the indications that conception has occurred are usually enu- 

 merated, stoppage of the menses, the placental murmur, the indications of 

 development of the mammary gland, its sense of pain or ten- conception, 

 derness, the color of the areola, the turgescence of the areola and nipple, 

 irritability of the stomach. Quickening, as it is termed, usually occurs 

 about the eighteenth week, and parturition in the fortieth, or at the close 

 of 280 days. With respect to this, it is admitted that the term may be 

 possibly .prolonged, in very rare cases, by 40 days. The French laws le- 

 gitimatize a child born within 300 days ; and that such variations of the 

 proper term may occur is proved by observations made upon domestic 

 animals, in which the duration of pregnancy can be ascertain- p er iod of ges- 

 ed with precision. In the cow, which has the same period of **&<>* 

 gestation as the human female, the shortest period hitherto observed is 

 213 days, the longest 336. The shortest period at which human par- 

 turition can occur, consistent with the viability of the child, appears to 

 be about 23 weeks. 



The act of parturition in its first stage is to be referred to a contrac- 

 tion of the muscular fibres of the fundus and body of the Mechanism of 

 uterus with a synchronous relaxation of those of the cervix, parturition. 



