428 



LIFE MOVEMENTS IN PLANTS 



Recorder, the short arm of the lever being 2'^) mm., 

 and the long arm 250 mm., the magnification being a 



FUt. Ia7. — The Quadruples Geotropic Recorder. 



hundredfold ; half that magnification is, however, sufficient 

 for general purposes. 



DETERMINATION OF THE CHARACTER OF GEOTROPIC 

 REACTION. 



The observed geotropic concavity of the upper side of a 

 horizontally laid shoot may be due to excitatory contraction 

 of that side, or ii may result from passive yielding to the 

 active responsive expansion of the low^er side. The crucial 



