i8 



Elementary Plant Physiology. 



a small, rapidly growing plant, and set it under the long end of 

 the lever. Attach a thread to the extreme tip of the stem by 

 a running loop, and bring the thread up to the lever, fastening 



it at such length as to hold the lever nearly horizontal. Fix a 

 metric ruler to a small wooden box, and set upright back of the 

 tip of the lever. A half hour later the plant will have adjusted 



