696 PHYSIOLOGICAL BASIS OF POLARITY. II 



There is another connection between root formation and geotropic 

 curvature. We have shown in a preceding paper^ that the curvature 

 is (kie to the fact that the under side of the cortex of a stem suspended 



Fig. 8. 



horizontally continues to grow in length while the upper side does not 

 do so to any appreciable degree. The photographs (Figs. 8 and 9) 

 show that if we disregard the basal end of the stem, the roots develop 



