XII. 



CEOPS 



239 



by sugar (glucose). Such grain is translucent, and owing to the great 

 shrinkage in drying, very wrinkled. 



Maize requires a warm climate and abundant sunshine. In most 

 soils the manures needed appear to be phosphates, lime, potash and 

 nitrogen, in the order given. 



In chemical composition, the maize grain varies considerably in the 

 different types. As a rule the proportion of fat is dependent upon that 

 of the 'germ in the grain, while the nitrogenous matter is chiefly deter- 

 mined by the proportion of horny matter present. 



The following table gives the average composition of various types, 

 all the figures, except those for water, having being calculated to a basis 

 of an average content of 13-32 per cent of moisture : 



The proteids of maize, according to Osborne, 1 consist chiefly of 

 zein and a proteid soluble in dilute potash solution, together with small 

 quantities of maysin, a globulin, an edestin and a proteose. Zein, on 

 hydrolysis, yields large quantities of leucine, glutamic acid, proline, 

 phenylalanine, tyrosine and alanine but no tryptophane, glycine, or 

 lysine. 



To the absence of tryptophane, the inability of zein to serve as 

 the sole nitrogenous food of animals is attributed by Willcock and 

 Hopkins. 2 



Others attribute the ill effects of zein upon animals to the presence 

 of phenylalanine and tyrosine, from which phenolic compounds are 

 readily split off, and to the poisonous effects of the phenols thus 

 formed. 



The carbohydrates of maize consist chiefly of starch, but sucrose, 

 glucose, dextrin and pentosans are also present. In the immature, 

 sweet corn, the sugar may amount to as much as 9 or 10 per cent. 



Rice (Oryza sativa) is a most important crop in many hot coun- 

 tries and forms the staple food of many millions of human beings. It 

 is generally cultivated in hot, swampy, unhealthy districts, but one 

 variety upland or hill rice will grow at an altitude of 6000 ft. and 

 without irrigation. Organic nitrogenous manures and superphos- 

 phates appear to be the chief manures used. Whole rice or " paddy " 

 is fairly rich in protein, fat and ash, but when deprived of its brown 



1 Jour. Amer. Chem. Soc., 1897, 19, 525. 2 Jour. Physiol., 1906, 35, 88. 



