1/8 THE TEACHING BOTANIST 



one set that gravitation may be made to neu- 

 tralize its own effects. This has been done in 

 Experiment i, in which the two sets of seeds 

 are under the same conditions of temperature, 

 light, moisture, food supply, and differ only in 

 their relation to gravitation. 



a. Has gravitation anything to do with the posi- 



tion taken by hypocotyl and plumule in 

 their growth from the seed ? Answer by 

 observation of Experiment i. 



All records of experiments should bring out 

 clearly : 



(1) Object of the experiment. 



(2) Method and appliances used. 



(3) Exact results observed. 



(4) Conclusions. 



b. In precisely what way does gravitation act 



to influence the up-and-down position ? 



c. Express synoptically your conclusions upon 



these points : - 



(1) For what good do stems grow up and 



roots grow down ? 



(2) By what influence are they guided 



into those positions ? 



(3) By what mechanical means are they 



brought around into those positions ? 



(4) Why is gravitation thus used instead 



of other external influences ? 



