Nutrition 



117 



TABLE 21. 



ESSENTIAL AND DISPENSABLE AMINO ACIDS WHEN AMINO ACID 



MIXTURES PROVIDE AN ANIMAL'S NITROGEN SUPPLY 



* Serine can replace glycine for Tetrahymena. 



fPhenylalanine and tyrosine not both needed; either one sufficient for Aedes. 



+Citrulline can substitute for arginine for Aedes. 



§Glycine and glutamic acid needed for maximum growth— chick. 



II Tyrosine needed if phenylalanine low— chick, rat, man. 



*|Arginine needed for growth, not for maintenance— rat. 



**Cystine needed only if methionine low— rat, man. 



