8 12 16 20 24 28 32 36 



-44 -46 



FIGURE 1. The thick lines show the survival periods (in days) of twenty-on< 

 individual mice upon the zein diet with tyrosine added. The thin lines show th< 

 same for nineteen mice upon the zein diet with tryptophane added. [From th< 

 Journal of Physiology > volume 35.] 



