AND ITS APPENDAGES. 649 



are often swallowed in the same way, and may be found in the 

 meconium. 



The gastric juice is not secreted before birth ; the contents of the 

 stomach being generally in small quantity, clear, nearly colorless, 

 and neutral or alkaline in reaction. 



The liver is developed at a very early period. Its size in pro- 

 portion to that of the entire body is, in fact, very much greater in 

 the early months than at birth or in the adult condition. In the 

 foetal pig we have found the relative size of the liver greatest 

 within the first month, when it amounts to very nearly 12 per cent. 

 of the entire weight of the body. Afterward, as it grows less rapidly 

 than other parts, its relative weight diminishes successively to 10 

 per cent, and 6 per cent. ; and is reduced before birth to 3 or 4 per 

 cent. In the human subject, also, the weight of the liver at birth 

 is between 3 and 4 per cent, of that of the entire body. 



The secretion of bile takes place, as we have intimated above, 

 during foetal life, in a very scanty manner. We have found it, in 

 minute quantity, in the gall-bladder, as well as in the small intes- 

 tine at birth ; but it does not probably take any active part in the 

 nutritive or other functions of the foetus before that period. 



The glycogenic function of the liver commences during foetal life, 

 and at birth the tissue of the organ is abundantly saccharine. It is 

 remarkable, however, that in the early periods of gestation sugar is 

 produced in the foetus from other sources than the liver. In very 

 young foetuses of the pig, for example, both the allantoic and 

 amniotic fluids are saccharine, a considerable time before any sugar 

 makes its appearance in the tissue of the liver. Even the urine, in 

 half-grown foetal pigs, contains an appreciable quantity of sugar, 

 and the young animal is therefore, at this period, in a diabetic con- 

 dition. This sugar, however, disappears from the urine before birth 

 and also from the amniotic fluid, as has been ascertained by M. Ber- 

 nard j 1 while the liver begins to produce a saccharine substance, and 

 to exercise the glycogenic function, which it continues after birth. 



Development of the Pharynx, (Esophagus, &c. We have already 

 seen that the intestinal canal consists at first of a cylindrical tube 

 terminated at each extremity of the abdominal cavity by a rounded 

 cul-de-sac (Fig. 241, c, c) ; and that the openings of the mouth and 

 anus are subsequently formed by perforations which take place 

 through the integument and the intervening tissues, and so estab- 



: Levonsde Physiologic Experira^ntale, Paris, 1855, p. 398. 



