148 THE AMINO ACIDS 



of which remains obscure. It is also evident that the 

 establishment of a satisfactory non-protein dietary 

 affords an opportunity for the study of any specific 

 influence which a peculiar type of protein, or one with 

 an unusual type of internal structure, may exert in 

 nutrition. 



In addition to casein Osborne and Mendel have 

 demonstrated that perfectly satisfactory results may 

 be yielded when other types of pure proteins are 

 employed, a single one sufficing for all the nitrogen 

 requirements of white rats. Thus, adequate growth 

 has been secured with lactalbumin from cow's milk, 

 ovalbumin from hen's egg, ovovitellin from hen's egg, 

 edestin from hemp seed, cannabin from hemp seed, glu- 

 tenin from wheat, glycinin from the soy bean, globulin 

 from squash seed, globulin from cotton seed, excelsin 

 from Brazil nut, and glutelin from maize. 



Taking advantage of the opportunity afforded them, 

 the above mentioned authors have studied the influ- 

 ence which a peculiar protein, for example, one lack- 

 ing one or more important amino acid, may exert in 

 nutritional processes. It soon became evident that all 

 proteins do not promote growth under otherwise 

 favorable conditions. Gliadins of rye and wheat, 

 which are deficient in glycocoll and lysine and on the 

 other hand are very rich in glutamic acid, and hordein 

 of barley, which closely resembles gliadin in chemical 

 constitution, are capable of giving maintenance, but 

 fail to induce growth. A condition of stunting is 

 brought about, old animals retaining the characteris- 



