NUTRITION \NI> OBOW1 II 



mixed either with zein al ■ or with zein plus small quantith 



tophane. It was found that, with zein alone, th<- m 

 maintain growth; they Losl in weighl and died in from abonl i 

 aboul a month. Other mice fed on the same amount of basal did 

 zein, bu1 to which was also .- 1 < 1 « 1 « ■ < I sunn- tryptophane, although they <li<i 

 qoI grow, were capable of maintaining their body v. eighl and lived in 

 Borne instances for nearly a month and a half. There w< 

 tions of t li»" differei ce in t he efficienc 

 on the zein alone were "very inactive, and remained 

 period of the time in a condition of torpor. The hair iffled, 



half closed, and the ear . I and tail were cold. Th< 



mals, however, gave evid< E having a g I appetite. ( >n the 



hand, the mice to which tryptophane was a manifested a strik- 



ingly differenl behavior, being active and more or rmal until 



jusl before death. Thai both groups of animals failed to live more than 

 forty-four or forty-eight days is probably to 1"- accounted for by the 

 absence in the zein of the other unit, lysine. Had this been added along 

 with the tryptophane i1 is probable, in the lighl of Mendel and I i 

 observations, thai the animals would have survived much long 



To supply the missing unit, besides using the pur.- amino acid, 

 may employ other proteins which contain tin required an I irve 



[II of Fig. 184 . That mixtures of protein f Istuffs are desirabl 



been apparent to those who have studied practical dietetics. We must com- 

 bine the unsuitable protein with others which, although in themselves 

 perhaps also unsuitable, ye1 furnish us with a mixture which contains all 

 the essential units both \'<>v maintenance and growth. As M ndel ints 

 out, these considerations suggesl thai we may be able to utili 

 of the low priced protein by-products of th< al, me i milk in- 



dustries. The tesl of the adequacy of the corrected diel m 

 be determined by experiments of the type which we have jusl described 

 II is probably in stock-raising rather than in connection with human nu- 

 trition thai these facts will prove of practical value; for, not only 

 of man more varied, but it contains animal p - in which the d< 



eies are no1 so common. 



Itfosl important w <<vk of this • I by McC 



lum and his collaboratoi It would take 



this book to discuss the results in detail, bul il m 

 they have shown that, since the adequi 

 multiplicity of factors besides the amino-acid make-up 

 some of which we shall discuss immediatel; 

 tions with various food mixtures must bi 

 of time. The nutritive valu< imon • 



ard did that hml brought the animals 



