146 THE VEGETATIVE FUNCTIONS OF PLANTS 
found significance to the plant of its ability so to adjust its 
organs as to bring them into harmony with surrounding 
influences. If a stem, bent over, could not erect itself, 
if leaves could not assume positions that secure the 
most favorable illumination, if stems and leaves were not 
correlated to each other, most plants would soon be out 
of harmony with their environment and would sicken and 
die. Fully one-half the leaves of the motherwort, illus- 
trated in Fig. 105, would have been deprived cf suitable 
illumination by adjacent plants, had they not possessed 
this power of adjustment. 
138. Purpose of Part DDL Chapters I to XI have dealt 
with all parts of the plant except the flower, and all the 
activities studied have been primarily for the sake of pre- 
serving the life of the individual plant. Flowers function 
primarily for the race to which the individual plant 
belongs; but they can be really understood only after a 
thorough study of the life histories of some of the lower, 
non-flowering plants. The study of life histories will be 
taken up in Part III. 
