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PROTEIN METABOLISM 



[PT. Ill 



In 192 1 Sznerovna made estimations of the nitrogen contained in 

 the body of the embryo, and that contained in the allantoic fluid 

 at different stages of incubation. She found that the ratio of these, 



Table 140. 



Day 



Milligrams nitrogen present in 

 embryo each day (cumulative) 



Milligrams nitrogen excre- 

 ted by the embryo up to 

 LeBreton each day (cumulative) 



Sznerovna's ratio 



(Nitrogen in embryo/ 



Nitrogen excreted) 



SchaeiTer Sznerovna Needham Sznerovna Murray LeBreton 



0-95 

 4-2 



5-5 



[4-1 



23-t 



6 

 0-00234 

 0-00500 

 0-0149 

 0-095 

 0-279 

 0-5344 

 0-8772 

 1-3161 

 I -8699 

 2-5546 

 3-3810 

 4-3376 

 5-5101 

 6-9155 

 8-8452 

 [1-0038 



17-5 



16-4 

 15-3 



566-2 

 533-4 

 325-6 

 106-5 

 47-7 

 39-32 

 37-13 

 38-59 

 41-64 



48-53 

 55-86 

 60-94 

 61-74 

 59-35 

 53-55 

 48-07 



9 



624-0 



420-9 



260-6 



68-3 



28-7 



23-4 



21-4 



24-3 

 30-8 



39-9 



45-5 

 48-9 

 48-1 

 46-6 

 44-1 

 34-3 



i.e. nitrogen in embryo/nitrogen in allantoic fluid, was practically a 

 constant, wavering round about 17 (see Table 140). In other words, 

 for every i gm. of nitrogen in 

 the allantoic fluid, there were 

 to be found 1 7 grams of nitro- 

 gen in the body of the embryo. 

 Her estimations did not begin 

 before the loth day, so in view 

 of the relations which we have 

 already found to hold between 

 the early and late periods of 

 development, a recalculation of 

 her ratio was desirable. 



It was assumed that only small 

 errors would be introduced by 

 calling the urea nitrogen plus 

 the uric acid nitrogen the nitrogen present in the allantoic fluid, and 

 two different sets of figures for the total nitrogen in the embryo were 

 available. The important difference between the nitrogen figures 



Days ^ 



Fig. 327. 



