THE BIO-CHEMISTRY OF ANIMALS AND PLANTS 697 



and Samuely for an interesting experiment with regard to the 

 synthesis of proteins in the animal body. These observers 

 found that on administering it to a horse which had previously 

 lost a large amount of blood, the composition of the serum 

 proteins remained constant. 



The alcohol-soluble protein of maize was called zein 

 by Gorham, and subsequently maize-fibrin by Ritthausen. 

 Osborne and Chittenden reinvestigated this substance and 

 retained the name zein. It is characterised by its solubility 

 in even strong alcohol of 96 per cent,, and its complete in- 

 solubility in water. Glutaminic acid is also present in large 

 quantities among its cleavage products, and lysine is absent. 

 The indole-molecule (tryptophane) is also missing, and zein 

 represents, therefore, a convenient material to investigate the 

 question how far the absence of certain cleavage products 

 influences the nutritive value of a protein. Hopkins and 

 Willcock found that growth was very favourably influenced 

 in young animals by zein and tryptophane, whilst zein itself 

 was insufficient. 



Hordein is the name given by Osborne to the alcohol- 

 soluble protein of barley. Its differs somewhat from wheat 

 gliadin in its solubilities, and contains more carbon and less 

 sulphur than the latter. The hydrolytic cleavage products, 

 examined by Osborne and Clapp, resemble quantitatively 

 those of the other gliadins. Lysine is absent, and as much 

 as 41 per cent, glutaminic acid was found. The most marked 

 feature, however, is presented by the very large percentage 

 of proline (pyrrolidine-carboxylic acid), which exceeds that yet 

 obtained from any other protein, being practically 14 per cent., 

 or twice as much as that yielded by wheat gliadin. 



4. The Phyto-caseins (or Phyto-vitellins). — These substances 

 are found in maize, barley, rye, and wheat, and amount in 

 some cases to nearly 50 per cent, of the total protein. When 

 these seeds are completely extracted by treatment with water, 

 followed by salt solution and subsequently alcohol, the residue 

 still contains a large amount of protein, which can only be 

 extracted by treatment with very dilute (o'2 per cent.) alkali. 

 From this solution they are precipitated by neutralisation 

 with acids. They are insoluble in water and alcohol, but 

 show both acid and basic properties, being easily soluble in 

 a slight excess of alkali or acid. The question of their per- 



