628 History of a Grain of Wheat. [Oct. t 



is probably also an actual disease factor involved. On all these 

 points experimental work is in progress. 



Transfer of Food Material from the Plant to the Grain. — 



Experiments have shown that the wheat plant practically com- 

 pletes its growth, as far as gathering material from the air and 

 from the soil is concerned, a month or five weeks before it is 

 harvested. In this latter period the valuable material already 

 accumulated by the plant is being moved from the stem and 

 the leaves to the seed. This migration is very incomplete. 

 The straw still retains half or more than half of the valuable 

 material manufactured by the plant. Considering that the 

 total material manufactured by the plant represents the limit 

 of its capacity as a living organism and is determined by condi- 

 tions outside our control, such as the soil and water supply, 

 one line of improvement must clearly be to increase the migra- 

 tion into the seed and to ensure that the greatest proportion of 

 the plant ends in the useful grain and not in the comparatively 

 useless straw. Improvement in this direction is especially 

 urgent in the drier countries where there is an absolute 

 limitation of the amount of growth by the insufficient water 

 supply. 



Milling of Wheat. — Turning now to the flour, the object of 

 the modern miller is not to grind wheat into a meal and then 

 sift out the flour, but to crack the berry with the least amount 

 of breaking up of the husk or bran, thus letting the endosperm 

 fall out in a clean condition. The best white flour is practi- 

 cally pure endosperm in a powdered state. It is the most 

 digestible part of the grain, and weight for weight yields the 

 most food. Before the War only about 68 per cent, of the 

 weight of the grain was recovered as white flour; the remainder 

 passed into the various offals, which were chiefly used for pig 

 feeding. Under the stress of w T ar it w r as necessary also to 

 bring into use the less digestible portions of the grain, and the 

 extraction of flour from w T heat w 7 as raised from 68 per cent, 

 to over 90 per cent. Careful digestion experiments w 7 ere made, 

 and they showed that this higher extraction and addition of the 

 less digestible portions of the wheat grain did increase the 

 amount of real food by an amount which was equivalent to an 

 extra two months' supply of wheat. The outer portions of 

 the wheat berry that are rejected from white flour do also con- 

 tain certain specially valuable food adjuncts, but, as many 

 people learnt, are not suited to all constitutions. 



Bread Making- — Flour made from the majority of English 

 wheats without any admixture produces small dense loaves, 



