7 3 2 CHEMISTR Y OF RESPIRA TION. 
prevent vigorous contractions of the uterus, the blood in the umbilical 
vein of the foetus was brighter than that in the arteries ; and that the 
difference in colour of the umbilical vein and arteries disappeared 
during - asphyxia of the mother, to reappear when artificial respiration 
was performed. Pfiiiger 1 had also noticed that the colour of the 
umbilical vein was reddish brown in the normal condition, but became 
black during asphyxia. 
The results obtained by Zweifel were confirmed and extended by 
Zuntz, 2 who showed that during asphyxia of the mother the foetal blood 
lost oxygen in the placenta, the blood of the umbilical vein becoming 
darker than that of the corresponding arteries: that when the maternal 
vessels supplying the placenta were compressed the umbilical vein 
became as dark as the arteries: that a foetus respiring air through its 
lungs lost oxygen in the placenta, which was left connected with an ex- 
cised piece of the uterus ; that during normal breathing of the mother 
the umbilical vein coming from the intact placenta contained blood as 
red as the arterial blood of the 'uterus, and that movements of the 
foetus made the blood of the umbilical arteries darker in colour. Zuntz 
maintains that the oxidation taking place in the foetus must be small, 
for the difference in the colours of the umbilical arteries and vein is 
slight, corresponding to a difference of about 1 per cent, in the amount 
of oxygen : and the foetus can live for a long time upon the oxygen in 
its blood, when respiration by the placenta or lungs is prevented. 
According to Zuntz's estimate, the human foetus would need daily 
0-169 grin, of oxygen per kilo, of its weight, as compared with 
14-15 grins., the amount required by an adult. 3 Pfiiiger 4 and 
Zuntz found that the blood of the foetus, in comparison with that 
of an adult, had a low specific gravity and was poor in corpuscles 
and haemoglobin : these results, however, are opposed to those 
of Hayem, 5 Hoesslin, 6 Sorensen, 7 Wiskemann, 8 Preyer, 9 Denis, 10 and 
others, 11 who found higher values for the foetus than for the 
mother. 
The difference in the tension of oxygen in the blood of the 
umbilical artery of the foetus and the maternal blood is small, 
but it is sufficient, owing to the intimate relationship of the 
maternal and foetal circulations, to supply the oxygen needed by the 
fcetus. 1 - 
Cohnstein and Zuntz 13 have analysed the blood of the umbilical 
artery of a foetal sheep, winch was 53 cm. long, weighed 153." gnus., 
1 Arch./, d. ges. Physiol., Bonn, 1S6S, Bd. i. S. 80. 
1 Ibid., Bonn, 1S77. Bd. xiv. S. 605. 
3 This is contested by Wiener, Arch. f. Gunnel:, Berlin, 1884, Bd. xxiii. S. 1S3. This 
paper gives numerous references to the work on the general metabolism of the fetus, but 
does not disprove the relatively small oxidation in the fretus. 
4 Arch./, d. ges. Physiol., Bonn, 186S, Bd. i. S. 61 ; 1875, Bd. x. S. 274. 
3 Compt. rend. Acad. d. sc, Paris. 1877, tome lxxxiv. p. 1166. 
6 Ztschr.f. Biol., Miinehen, 1882, Bd. xviii. S. 612. 
7 Jahresb. ii. d. Fortschr. d. Awed. a. Physiol., Leipzig, 1878, Bd. v. Abth. 3, S. 192. 
8 Ztschr.f. Biol., Miinehen, 1876, Bd. xii. S. 434. 
a " Speeielle Physiol, des Embryo." Leipzig, 1883, S. 144. 
10 Ann. de chim. etphys., Paris, 1842, Ser. 3, tome v. p. 313. 
ii Poggiale, Coi/ipf. rind. Arm!, d. *-., Paris, 1847. tome xxv. p. 112; Panum, 
Virchow's Archiv, Bd. xxix. S. 4S1. See also Cohnstein ami Zuntz, Arch. f. d. ges. Physiol., 
Bonn, 1884, Bd. xxxiv. S. 183. 
12 Zuntz, ibid., 1877. Bd. xiv. S. 626. 
13 Arch. f. d. ges. Physiol. Bonn, 18S4. Bd. xxxiv. S. 206, 231. 
