THE FLOWER 139 



RIPENING OF THE GRAIN 



The ovary of the fully developed flower before fertilisation resembles 

 a blunt inverted cone, and is about i mm. long and i mm across the 

 broad stylar end (Fig. no). 



After fertilisation it increases in volume from day to day, reaching 



Fie. 1 10. Grain showing changes in size and form during development ( 2-7). 

 a, June 27 ; b, July 4 ; r, July 12 ; d, August i ; t, August 15 (ripe). 



its maximum size in four or five weeks, after which it shrinks through 

 the loss of water during the next three or four weeks until the grain is 

 ripe (Fig. no). 



The following measurements record the changes in length, breadth, 

 from side to side, and thickness measured from dorsal to ventral side ol 

 developing grains. 



" SWAN " WHEAT (7*. 



In the early stages of ripening the length, breadth, and thickness all 

 increase more or less uniformly, but in the later stages the length increases 

 while the diameters are reduced, the fjrain becoming longer and narrower. 



In addition to a change of volume and form there is a gradual altera- 

 tion in the weight, water content, and the amount of dry matter in the grain 

 as ripening proceeds. These variations are given below. 



