1-0 



Differential increase of 

 ammonia, urea and uric acid 

 excretion by chick embryos 

 (Needham's experiments) 



O Ammonia 



• Urea 



® Uric acid 



•001 



•0001 



U1719 141719 



Control +0-1CC. +0-1cc. +0'1cc. +0-1cc. 



normal 10% 20% 10% lO/ourca 



urea lactic tartronic +0-lcc. 



acid acid 10^ tartronic acid 



I I I' I 'I I 



3 4 5 6 7 8 9 10 1112 13 14 15 16 17 18 19 2021 



Days of development 



Fig. 324. 



