Development of Acid -Base Control 



215 



it is evidently lower even than the excretion of ammonia. 

 By one year of age the glomerular filtration rate/kg. had risen 

 above that of adults (McCance and Widdowson, 1952), and 

 more ammonia and surplus anions per kg. were being ex- 

 creted (see Figs. 1 and 3); the amount of ammonia excreted 

 per ml. of glomerular filtrate was near the adult level. 



08 



0-7 



0-6 



0-5 



t O 3 





0-2 



Ol 



Adult 



Before O- 24- 7- I 

 birth 24h. 48h. Sday year 



Fig. 4. The ratio of the ammonia excreted 



(m-mole/24 h.) to the glomerular filtration 



rate (ml./min.). 



The nature of the titratable acidity 



Fig. 5 shows the excretion of titratable acid per kg. of body 

 weight by the babies and the adults. The amount excreted 

 was low during the whole of the first week, but it was rising 

 even though the urine still contained no phosphates. The 

 high excretion at a year is again related to the high intake of 

 protein at that age. 



Fig. 6 shows the percentage of the titratable acidity due to 

 phosphate in the urine of an adult and in the urine of a breast- 

 fed baby in the first week of life. In the adult the percentage 

 depends upon the pH and, since the pH of the urine passed 



