NUTRITION AND GROWTH 141 



whether addition of any amino acid would produce 

 an effect, and hence, therefore, to find out directly the 

 specific action of tryptophane. 



A prominent feature in connection with the mice 

 given zein alone was a condition of torpor; the mice 

 were very inactive and made no movement when 

 handled or touched, the ears, feet, and tail were cold, 

 the coat was glairy and the eyes were half-closed. 

 Those fed tryptophane with zein showed a strikingly 

 different behavior, being active and apparently healthy 

 even up to the end of life. In both instances death 

 was not caused by a lack of food intake, as all animals 

 gave evidence of appetite. Quantitatively, sufficient 

 food was received but qualitatively something essen- 

 tial to life was lacking. It is possible that had lysine, 

 the other amino acid lacking in zein, been fed also, 

 even better results would have been obtained. Tryp- 

 tophane undoubtedly is essential for the maintenance 

 of life, although the specific role it plays has not yet 

 been determined. As the authors mentioned above 

 point out, "If it [tryptophane] serves as a basis for 

 the elaboration of a substance absolutely necessary 

 for life something, for instance, of an importance 

 equal to that of adrenaline then, in starvation, or 

 when it is absent from the diet, a supply is likely to 

 be maintained from the tissue-proteins, the demand 

 for it would become one of the factors determining 

 tissue breakdown. In the case of young animals which 

 directly benefit from the addition of a protein con- 

 stituent otherwise absent from their diet, to the extent 



