66 CHANGES OF COMPOSITION [chap. 



soil to soil, climate to climate, etc., than the grain. 

 When the filling of the endosperm has been pretty well 

 completed — which is about a week or a fortnight before 

 the time at which the grain would usually be regarded 

 as fit to cut — the ripening process sets in, and this is, in 

 the main, characterised by a drying up of what has been 

 previously accumulated. During this last fortnight the 

 dry matter of the grain increases little, if at all ; certainly 

 it is stationary in amount, or even declining, during the 

 last week, and water is being constantly removed. The 

 main feature, then, of the ripening process is desiccation ; 

 at the same time, other rearrangements in the chemical 

 nature of the constituents can be seen : non-protein 

 nitrogen compounds pass over into the protein state, 

 and the proportion of sugar falls, but these changes are 

 not large compared with the drying up which is taking 

 place. It would appear that it is possible to cut wheat 

 rather earlier than the usually recognised stage of 

 ripeness without any loss of weight in the crop, by 

 which means losses by shedding, birds, etc., might also 

 be reduced, the only practical question being whether 

 the final drying process can be better effected while the 

 wheat is standing, or after it is cut and shocked or even 

 put into stack. 



Certain other practical consequences depend upon 

 this migration process ; for example, if from any cause 

 the crop is cut before migration is complete, then the 

 straw will be so much richer in both fertilising and food 

 constituents. Similarly, in bad seasons, when ripening 

 is imperfect, the migration process is always found to be 

 much less complete, so that a higher proportion of the 

 accumulated material is left in the straw. Heavy 

 manuring, again, especially manuring of a nitrogenous 

 character, is always attended by a less complete migra- 

 tion, leaving the straw by so much the richer. Straw 



