LOOM IS] STUDY OF GERMINATION 205 



in the direction where soil usually is found, while the plumule 

 whose function is to spread leaves to sunlight persists equally 

 well in growing upward, or in the direction in which sunlight is 

 usually met. It has been customary to say gravity causes the 

 caulicle to grow downward, but why the pull of gravity should 

 not influence the plumule in a like way is beyond our understand- 

 ing. Whatever the true explanation of the contra movements of 

 caulicle and plumule, the fact that they persist in growing in 

 opposite directions is something to cause every one to marvel at 

 the adaptations these parts display for the good of the plant. 

 Notwithstanding stones and hardness of soil, caulicles are found 

 working their way with marked success into regions of food, 

 overcoming difficulties in the shape of obstructions and distances 

 through which they must grow that never fail to surprise the 

 observer. Likewise the plumule while in a compact form forces 

 its way between hard masses of soil and around stones on its way 

 to air and sunshine above. Were not caulicle and plumule able 

 to respond to the stimuli that gives them the directions in which 

 to grow, and were they less persistant in pushing forward on 

 their journey to soil and sunshine, the sprouting of seeds would 

 present difficulties that would very much modify present prac- 

 tices. 



