I04 THE CEREALS IN AMERICA 



do not crush under the pressure of the thumb nail. After that 

 time the increase is slight. The indications are that if allowed 

 to stand beyond the period of full maturation, a slight decrease 

 in the actual substance of the grain may take place. This is 

 explained by Deherain on the ground that the seed continues 

 to respire, thus giving off carbon dioxide. 



159. Influence of Ripening Upon Composition. — In general, 

 there is a decrease in the percentage of ash, nitrogen and fiber 

 as the grain ripens, due to the increase in carbohydrates other 

 than fiber. This is due to the endosperm developing later in the 

 growth of the wheat. The germ develops first, and later, when 

 the endosperm develops, the percentage of ash and nitrogen 

 becomes less, although the actual amount may remain the same, 

 or, as is probably the case, may increase. The changes in com- 

 position after the grain has reached the dough stage appear to 

 be very slight.^ 



While the stage of maturity of grain through the ordinary 

 range of wheat harvest does not affect materially the quality 

 (composition) of the grain, climatic conditions which affect the 

 full maturity of the grain may materially modify the quality. 

 The higher percentage of nitrogen in the spring wheat is prob- 

 ably due, in part at least, to a lack of full maturation. (74) 

 The per cent of nitrogen decreases somewhat in the straw 

 up to the dough stage. The per cent of crude fiber increases 

 in the straw throughout the ripening period, while there are 

 corresponding decreases in the other carbohydrates. 



160. Influence of Shocking. — There is always danger of over- 

 ripe grain shelling out in the harvesting, and there is also 

 danger of lodging. It is not good farm practice, therefore, to 

 delay han^esting until wheat is entirely ripe. Investigations 

 have proved beyond question that at the early stages of seed 

 fcormation a considerable transfer of material from the straw to 



1 Mich. Bui. loi, p. 8. 



