W. E. BllENCIILEY AND A. D. IT ALL 



203 



fairly constant : there is some indication of" a rise towards the end, but 

 the curves are not smooth enough to be sure of this, though as will be 

 seen later it is explicable by the continued loss of non-nitrogenous 

 matter by respiration. The actual nitrogen in 1000 grains (Fig. 7) 



Plot 10 

 R.F. 

 Plot 3 



3 6 9 12 15 18 21 24 27 30 33 38 39 days 



Fig. 7. Actual nitrogen contained in 1000 grains, 1907 and 11108. 



rises regularly until the last three-day period. The very steady incre- 

 ment of nitrogen in itself disposes of the opinion that the nitrogenous 

 constituents enter the endosperm first, and that the later filling of the 

 grain consists mainly of starch. Confirmation is obtained by recalcu- 

 lating the results so as to ascertain the proportion of nitrogen in the 

 dry matter that has entered the grain between successive dates, though 

 the figures obtained can only be viewed very generally, because the 

 experimental errors are accumulated in quantities that are not them- 

 selves large. Comparing, however, the first and second halves of the 

 whole period we get the following proportions of nitrogen in the dry 

 matter. 



Percentages of Nitrogen in Dry Matter entering the Grain. 



Plot :3. 



July 19— August 6 1-667 



August 6—24 1-681 



14—5 



