462 



Messrs. A. D. Hall and C. G. T. Morison. [Dec. 22, 



that date several of the plots happened to yield an exceptionally small 

 number of stems on the area harvested. 



For the better calculation of mean results the smoothed curve also shown 

 in fig. 1 was drawn ; by combining the smoothed dry weights read off this 

 curve with the true mean percentages at each date were obtained the data 

 contained in Table IV and expressed graphically in fig. 2. 



Juneia 20 27 July 4 II 18 25 Awgl 8 



Fig. -2. — Dry Matter, Nitrogen, Phosphoric Acid, and Silica in Whole Plant and Grain. 

 Means calculated on smoothed weights of whole Plant. (SiO., on h scale of N and 



PA.) 



From these curves it will be seen that the dry matter of the crop goes on 

 increasing until about a fortnight before cutting, but the whole of the 

 nitrogen would appear to have entered by July 11, a fortnight before there 

 was any sensible grain. The phosphoric acid seems to reach its maximum at 

 a slightly later date, and the figures for the silica, though subject to greater 

 errors of determination, show that the assimilation of silica continues still 

 later, until the grain has progressed somewhat. Of the nitrogen within the 

 plant, about 63 per cent, is eventually moved into the grain and rather less 

 than 70 per cent, of the phosphoric acid : the migration of the phosphoric 

 acid does not, however, take place exactly pari jiasm with that of the 

 nitrogen, but follows it somewhat. Of the silica but a small proportion, 

 9 per cent, at the maximum, reaches the grain, and nearly the whole of this 

 is transferred in the earlier stages of grain formation, being doubtless pi'esent 

 in the adherent pales and glumes and not in the seed proper. 



