CHANGES DURING PREGNANCY 533 



coefficient," is increased. It must be clearly understood that this 

 percentage increase in the ammonia nitrogen and decrease in the 

 urea nitrogen refer to the relative proportion of nitrogen excreted 

 as these two substances and not to the absolute amounts excreted, 

 which are diminished. The ammo-acid nitrogen was found bv 

 Leersum l in forty per cent, of pregnant women on the hospital diet 

 to amount to ten per cent, and more of the total nitrogen, whereas 

 it varies between 27 and 7'7 per cent, in the non-pregnant. Similar 

 high figures were obtained by Murlin. Wilson- also found an increase 

 in the amino-acid nitrogen. Polypeptides have also been observed. 3 

 The occurrence of creatin in the urine of normal pregnant women 

 on a creatin-free diet was first demonstrated by Krause and Cramer 4 

 and confirmed by other workers. 5 



These facts have been the chief support of the idea referred to 

 above (see p. 520), that even in normal pregnancy the metabolism is 

 faulty : the high ammonia-nitrogen percentage has been interpreted 

 as indicating an acidosis, the high amino-acid nitrogen was taken as a 

 sign of hepatic insufficiency in the sense that the power of the liver to 

 split off ammonia from the amino-acids of the proteins was impaired. 

 The presence of creatin was looked upon by some authors as a confirma- 

 tion of the existence of hepatic insufficiency. Further confirmation 

 was believed to be presented by the change in the distribution of 

 the sulphur in the urine. The inorganic sulphate sulphur was 1<>\\ 

 in percentage like the urea nitrogen, the unoxidised or neutral 

 sulphur was increased. This was interpreted by Hoffstrom as a 

 diminished power of oxidation on the part of the mother. From 

 this point of view the toxaemias of pregnancy 'and eclampsia, in 

 which very high values for the percentage of ammonia nitrogen had 

 been found, appeared merely as an exaggeration of a pathological 

 metabolism which exists throughout pregnancy. 7 In 1912 Murlin 8 

 wrote: "This theory has obtained so firm a foothold that to-day 

 many obstetricians consider it an additional reason why chloroform 



1 Leersum, " Die Ausscheidung von Aiuiiumauren wiihrend der Schwanger- 

 schaft," Rior/ti'm. Z>-it$i>h., 1908, Festschr. f. Hamburger. 



2 Wilson (K. M.), "Nitrogenous Metabolism in I'lt-u'iiam \ , ./'//,.< //<//////.< 

 Hosp. Bull., vol. xxvii., 1916. 



' Falk and Hesky, " Ueber Ammoniak, Aminosuuren und Peptid-Stickstoff 

 im Harn Gravider," Zeit-sch. f. klin. Mc<L, vol. Ixxi., 1910. 



4 Krause and Cramer, "The Occurrence of Creatin in Diabetic Urine," 

 Proc. P/tf/x. >'<-., Jour. <>f P/ii/siot., vol. xl., 1910. 



5 Van Hoogenhuyze and Doeschate, "Recherches sur lex echanges organ - 

 iques chez les femmes enceintes," Aim. >/' <!i/n. <-f <rnl,*t<'ti:, vol. xxxviii., 

 1911. 



6 Hoffstrom, /<. //. Murlin, /<. <-it. 



7 Ewing and Wolf, "The Metabolism in the Toxaemia of Pregnancy," .!;//</. 

 Jour. ObtteL, vol. lv., 1907. 



8 Murlin and Bailey, " Protein Metabolism in late Pregnanc-y and the 

 Puerperium," Jour. Ai/fr. .!/<'/. A us., vol. lix., 



