io6o 



PROTEIN METABOLISM 



[PT. Ill 



with the production of haemoglobin and the second with the formation 

 of the bile pigment, which is so noticeable a constituent of the egg 

 in the last few days before hatching, Sendju estimated tyrosine in 

 the same way, using the method of von Fiirth & Fleischmann, and 

 the results he obtained are plotted in Fig. 296. The general picture is 

 very like that for tryptophane — the total amount of the amino-acid 

 decreases, both in yolk and white, while the fraction of it contained 

 in the embryonic body rises to meet the descending total curve at 

 hatching. Sendju's values for the total amount of tyrosine agree to 



Sendiu (Trypbophane) e Embryo 

 I -f ■" <- o White 



• Yolk 

 e Whole egg 



Days 



Days -> 5 



Fig. 295. 



Fig. 296. 



some extent with those given by Plimmer & Lowndes, better at the 

 latter part of the curve than at the former. The fall was regarded by 

 Sendju as indicating the utilisation of the tyrosine for hormones and 

 other special purposes. 



Sendju's estimations of the content of arginine, histidine and lysine 

 are shown in Figs. 297 and 298. There is a general similarity between 

 the graphs, for the amount of substance in the embryo regularly rises 

 till it has absorbed all that outside, while the yolk and white curves 

 show that the material of the white is used regularly before that of 

 the yolk. The behaviour of the curves for total amino-acid, however, 

 shows some variation, histidine distinctly rising, lysine less so, and 



