W. E. Brenciiley and A. D. Hall 107 



its constituent cells were followed microscopically. An jiccount of this 

 latter part of the work has already been published by one of us' ; it will 

 be sufficient here to say that no connexion could be traced between 

 the progressive changes in the nature of the contents of the cells of 

 the endosperm or their final structure, and the strength of the flour 

 resulting from the grain. 



The following paper deals with the chemical side of the work. 



Method. In tracing the progressive changes in the migration of the 

 materials and the filling up of the wheat grain it is necessary to 

 ascertain the total yield on a unit area at a series of dates throughout 

 the process, because the same plants cannot both be analysed and also 

 allowed to grow on for analysis at a later date. This necessity at once 

 introduces a large experimental error : even if comparatively large plots of 

 Jjjth acre, could be harvested at successive dates, the experimental error 

 in the yield on each occasion would be not less than 10 per cent., and it 

 is increased when the plots are reduced to the very much smaller sizes 

 which alone are manageable in work of this kind. Errors of this 

 kind vitiated the conclusions reached in certain earlier trials not here 

 reported ; in one year particular drills in a wheat field were selected as 

 uniform to the eye, and on each date a fixed number of yards of corn 

 were cut along these drills ; in another year a hundred good ears were 

 selected on each date. The results in both cases led to certain con- 

 clusions, but the experimental error was evidently too large, so the results 

 have been discarded, though they agree with the data obtained by the 

 more accurate methods followed in 1907 and 190<S. 



Certain plots of wheat were selected to provide material, and on a 

 given day when the wheat was coming into flower all available assistants 

 proceeded to mark by means of ties of red wool about 3000 heads of 

 wheat which were in just the same stage of development, as shown by 

 the fact that they had protruded one or more anthers from the middle 

 florets of the ear. Only central stems were marked, never secondary 

 tillered shoots ; thus the work began with material as nearly as possible 

 uniform and at the same stage of development. From among these 

 selected shoots cuttings were made at three-day intervals ; the material 

 was brought down to the laboratory and as rapidly as possible the grain 

 was picked from the heads. Several lots of 1000 grains were then 

 counted out, weighed, dried and weighed again. The bulk of the grain 

 was also dried for analysis. Finally all the analyses were calculated 

 on the basis of the material contained in 1000 grains, this being a 

 1 W. E. Brenchley, Ann. oj Botany, Vol. 23, 190y, 117. 



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