CHANGES IN THE MATERNAL ORGANISM 519 



It is possible, though not yet proved, that, in addition to 

 carbonic acid, incompletely oxidised substances may be brought 

 to the placenta from the foetus and oxidised there or in the 

 mother (Bohr 1 ). Such a hypothesis lies at the foundation_of 

 the theory that certain pathological conditions in pregnancy 

 are due to the circulation of toxins manufactured in the product 

 of conception. 



With regard to the total energy exchange, the results of 

 Magnus -Levy, 2 F. Muller, 3 and E. Zuntz 4 tend to show that in 

 the human pregnancy no decrease in metabolism occurs, the 

 metabolic changes being at least as active in the foetus as 

 in the mother. In one experiment Levy found a progressive 

 increase in the oxygen intake during pregnancy, but he does 

 not lay too much stress on the figures, 5 as in all the others no 

 increase in the gaseous exchange per kilo was established. 

 Even in the third month there was a marked increase. The 

 weight increased from 108*4 to 111 '4 kilo, and the oxygen 

 intake from 302 to 320 c.cm. per minute, i.e. from 279 to 

 2'88 c.cm. per kilo per minute. With such figures we 

 must conclude that the early stages of pregnancy have had 

 a favourable influence on the growth of the mother 

 animal, and at the same time have led to a more energetic 

 metabolism. 6 



1 Bohr, Nagel's Handbuch der Physiologic, " Kespiration." 



2 Magnus-Levy, " Stoffwechsel und Nahrungsbedarf in der Schwanger- 

 schaft," Vortrag, Zeitschr. f. Geburtsh. u. Gynak., vol. Hi. ; also v. Noorden, 

 loc. cit., vol. i. 



3 F. Muller, " Diskussion zum Vortrag von Magnus-Levy," see v. Noorden, 

 loc. cit., vol. i. 



4 E. Zuntz, " Der Stoffaustausch zwischen Mutter und Frucht," Ergebn. d. 

 Phys., 1908. 



5 The older investigations of Oddi and Vicarelli ("Influence de la gros- 

 sesse sur 1'echange respiratoire," Arch. ital. de Biol., vol. xv., 1891), showed a 

 progressive increase in the consumption of oxygen during the last third of 

 pregnancy in rats ; but Magnus-Levy raises the objection that the movements 

 of the animals were not restricted. 



6 Such a result is in conformity with those obtained in rats soon after 

 inoculation with malignant new growths ; Cramer (W.), " The Gaseous Meta- 

 bolism in Eats inoculated with Malignant New Growths," 3rd Scient. Rep., 

 Imperial Cancer Research Fund, London, 1908). Magnus-Levy's exceptional 

 result may, however, be due to the fact that the woman under observation 

 had not yet completed her growth. 



