1920] 



SCHLEY— GEO-PRESENTATION AND GEO-REACTION 



79 



The effect of geotropic stimulation upon the cell structure of 

 the responded shoot was determined through microscopical exami- 

 nation. Longitudinal sections from concave to convex side of the 

 completely responded shoot in the region of the angle of greatest 

 curvature were cut on the freezing microtome, and camera lucida 

 drawings were made of corresponding areas on the concave and 

 convex flanks of the organ (figs. 4, 5). 



* 



TABLE II 



Relative respiration 



Seedling 



Roots 



Sunflower . . . 

 Sunflower... 



Zea Mays . . . 

 Shoots 



Vicia Faba. . 

 Vicia Faba . . 



Vicia Faba . , 



Left chamber 



Horizontally placed 

 Vertically placed 



Horizontally placed 



Convex side 

 Convex side 



Concave side 



Right chamber 



Time 



stimulated 



Vertically placed 

 Horizontally 



placed 

 Vertically placed 



Concave side 

 Concave side 



Convex side 



10 minutes 

 2 hours, 31 



minutes 

 4 hours, 58 



minutes 



Time in 

 apparatus 



4 minutes 



4 minutes 

 4 minutes 



2 minutes 



3 minutes 

 7 minutes 



Greater precipita 

 tion of BaCOj 



Horizontal root 



Horizontal root 

 Horizontal root 



Convex (much greater) 



Convex side 



Convex side 



" 



N > 



A study of fig. 5 shows that the cells on the convex side are 

 larger than those on the concave side. A 10 cm. square on the con- 

 vex side contains 40 cells, while a corresponding area on the concave 

 side shows 72 cells. This result is in accord with the work of 

 previous investigators. 



Summary 



1. The reducing sugars remain constant throughout stimulation 



and response. 



2. The hydrolyzable sugars increase on the convex side at the 

 expense of the polysaccharides as response takes place. 



3. The total sugars are constant until beginning of response, 

 when the sugars of the convex side become greater. 



4. The osmotic pressure increases until visible curvature has 

 taken place. At the end of the reaction both flanks show the same 

 osmotic pressure, which, however, is greater than that of the normal 



shoot. 



5. Respiration of the geotropically stimulated root is greater 

 than that of the unstimulated organ. 



