224 THE FCETUS. 



cause such opinions to be appreciated at their just vakie; I shall 

 content myself with remarking here, that in order to admit of what 

 is called a great circulation, the pulsations of the foetal must be iso- 

 chronous with those of the maternal heart. But the mode of aus- 

 cultation introduced by M. Kergaradec proves, as it had indeed 

 been before remarked by Diemerbroeck, that there is no such iso- 

 chronism, and that the fcetal heart beats one half oftener than that 

 of a majority of women. 



574. If it were true that the blood of the umbilical arteries is 

 poured as pretended, into the placental sinuses, it evidently would 

 mix with that of the uterine arteries, which, according to the same 

 theory, is also deposited therein; if so, we must be compelled to 

 believe that the absorbing mouths of the umbilical veins have the 

 faculty of choosing the arterial blood out of this mixture, while the 

 uterine veins take up only venous blood: such an idea is not to be de- 

 fended. Besides, as the matter of injection, even the coarsest, pass- 

 es with an astonishing facility from the arteries to the veins of the 

 placenta without being effused on its uterine surface, it appears tome 

 that we may with certainty conclude that the blood of the foetus is 

 not taken up by the womb. 



575. This does not, however, imply that the blood from the arte- 

 ries re-enters the umbilical vein without undergoing any changes; 

 but rather, only that these changes, purely molecular, are effected 

 in the placenta itself. This elaboration is not the less undeniable 

 because its essence is not understood. It may be compared to that 

 which is effected after birth in the general capillary system; and to 

 that which occurs in the secretory organs, and in the lungs themselves. 

 The fluids of the ovum are brought into contact with those of the 

 mother, and at that instant a change of principles is effected between 

 them, as takes place in the bronchia between the atmospheric air 

 and the venous blood of the lungs; but here all our information is 

 limited. 



576. In the liver. The truly enormous size of the liver during 

 the intra-uterine life, long ago gave rise to the supposition that it 

 was an organ of hematosis, or that it modified the blood in some 

 manner. M. Lobstein appears to be still of this opinion. Fourcroy 

 says that if this modification does take place, it must consist in a 

 kind of decarbonisation and dishydrogenisation. More recently 

 still, MM. Prevost and Dumas thought they had observed that the 

 first blood globules of the foetus appeared in the liver. If, says M. 

 Geoffroy de Saint Hilaire, the liver receives so great a quantity, and 

 exhibits such a considerable size, it is, that it may secrete a great 

 quantity of bile, which, being poured into the small intestine, occa- 



