Growth 



307 



176. Evidences of growth. - - Observed as a whole the 

 growth of any crop from seed-sowing to harvest is an 

 obvious phenomenon. In general, the popular concep- 

 tion of growth in flowering plants is that conspicuous 



FIG. 77. The effect of complex factors on the growth of corn. 



form of increase in size and weight which may be noted 

 as the seedling develops into the mature plant, as the 

 rapid exfoliation of leaves, or as the unfolding of the 

 flower-cluster. Growth is associated with the formation 

 and extension of living cells, and it may result in pro- 

 nounced changes in external form or in internal structure. 

 Growth involves at least two distinct phases. The one 

 is increase in length, and often in size - - extension ; the 



