72 



BOTANICAL GAZETTE [july 



great variation in the amount of homogentisic acid in different 

 analyses of normal shoots as Czapek found between the stimulated 

 and unstimulated organs. 



In her work on thermotropism of roots, Eckerson (6) found 

 the greater permeability to be on the concave side of the root, and 

 that this permeability changed with the changed thermotropic 

 reaction of the root. 



Scope of experiment 



The work here presented is a continuation of that reported in a 

 previous paper (18), which dealt with the acidity of the normal 

 shoot, and compared the acidity of the two flanks of the geo- 

 tropically stimulated shoot. The present paper deals with the 

 changes in metabolism of the carbohydrates, the difference in 

 osmotic pressure, and the difference in respiration of the upper and 

 lower flanks of the geotropically stimulated shoot through presenta- 

 tion and reaction periods. Vicia Faba seedlings were employed 

 throughout the experiment because they respond readily to geo- 

 tropic stimulation, and because they are large enough to be easily 

 split longitudinally. Trouble was experienced in germinating the 

 seeds because of the development of mold. To overcome the 

 difficulty the seeds were washed in tap water and then soaked two 

 or three minutes in a i per cent solution of silver nitrate and 

 rinsed thoroughly. They were grown in sand which had been 

 sterilized by boiling in water an hour or longer, and then put into 

 sterile pots while hot and allowed to stand until the following day 

 before planting the seeds. 



Carbohydrates and proteins 



For this analysis etiolated seedlings of Vicia Faba, grown in 

 sand in the greenhouse at a temperature of about 20 C, were used. 

 When the seedlings were 6-8 cm. high they were geotropically 

 stimulated for periods ranging from 15 minutes to 5 hours. 

 Duplicate analyses of samples for each period of stimulation, as 

 well as duplicate analyses of the unstimulated organ as controls, 

 were made. 



The epicotyls were split longitudinally into right and left 

 halves (fig. 1) in the controls, and into upper and lower halves 



