II02 PROTEIN METABOLISM [pt. iii 



first attacked this problem, estimated the sulphates in the allantoic 

 liquid, and found, as will be described in Section 12-7, that at least 

 as early as the gth day ethereal sulphates were accumulating in the 

 embryonic excreta, showing a detoxication of phenols by synthesis 

 with sulphuric acid. But his work on ornithuric acid was more 

 remarkable. As is well known, the metabolism of the bird reacts to 

 the presence of benzoic acid by combining it with ornithine (diamino- 

 valerianic acid) and excreting it in that form — a mechanism doubtless 

 developed because of the vegetarian diet, and its accompanying 

 abundance of unbreakable benzene rings. In order, therefore, to 

 discover at what stage in development the chick could first bring 

 about this synthesis, Takahashi injected small amounts of sodium 



Table 146. 



The ornithuric acid was identified by solubilities, melting-point and complete ele- 

 mentary analysis. In control normal embryos no ornithuric acid was ever found in 

 any part of the egg. 



benzoate into the egg-white before incubation, and then worked up 

 the various component parts of the egg for benzoic and ornithuric 

 acid. His results, which are given in Table 146, were remarkable, 

 partly because of the large number of eggs used, amounting to 

 some thousands, each one of which received by injection 5 mgm. 

 of sodium benzoate in 10 per cent, solution. The results showed 

 definitely that no ornithuric acid was formed up to the gth day, and 

 that the benzoic acid was then being excreted unchanged, but that 

 on the 14th day, on the contrary, ornithuric acid was undoubtedly 

 being manufactured. It would probably be legitimate to conclude 

 from this that the power to conjoin benzoic acid and ornithine is not 

 always present in the chick embryo, but arises at a definite stage in 

 its development. 



