92 D. NOEL PA TON, B. P. WATSON, AND J. KERR ON 



The results of our determination of the non-protein nitrogen show that excretory 

 products are constantly present in both fluids throughout the whole of pregnancy, 

 and that in the sheep, as Doderlein found in the cow, an increase occurs as pregnancy 

 advances. From the beginning and throughout the whole time the amount is higher 

 in the allantoic than in the amniotic fluid. 



The study of the distribution of nitrogen in the various excretory substances is still 

 under investigation, but the observations so far made show — 



1st. That in the amniotic fluid somewhere between 70 and 80 per cent, of the 

 nitrogen is in the form of urea (or allantoin?), and that the proportion is not altered 

 throughout the course of pregnancy. 



2nd. That in the allantoic fluid only about 50 to 70 per cent, of the nitrogen is in 

 urea and allantoin. 



That a large amount of this nitrogen of the amniotic fluid is urea has been demon- 

 strated by the separation of urea as the oxalate. 



The constant occurrence of nitrogen in simple combinations, and the fact that a 

 considerable proportion of this is urea, is a strong argument in favour of the view that 

 both allantoic and amniotic fluids are derived from the foetal kidney. 



(d) Pigment. — At the beginning of pregnancy both allantoic and amniotic fluids 

 are colourless, the amniotic fluid being water-clear and the allantoic slightly turbid ; 

 but in the later stages the amniotic fluid of the sheep becomes of an amber-yellow 

 colour. In the cow the allantoic fluid has the same colour, but the amniotic fluid often 

 becomes colourless. 



After shaking with ether a brown fluid is left, which gives the spectrum of urobilin. 

 This further indicates the renal origin of the fluid. 



(e) Sugar. — The earliest record of the presence of sugar in the foetal fluids which we 

 have found is by Majewski (loc. cit., 1858). Subsequent observers, e.g. Doderlein, 

 have failed to observe it. 



We have found it to be a constant constituent of both allantoic and amniotic fluids 

 of the sheep, cow, pig, cat, and dog, and of the mixed fluids of the rabbit, ferret, and 

 guinea-pig. 



The variations in its amount in the two fluids throughout pregnancy have been 

 studied in the sheep. The analyses were made in the usual manner by Fehling's 

 method. The results are given in the following tables (K and L) : — 



