INDEX 



417 



iron, 253 ff., 260, 270 flF., 298, 

 382, 385; in plants, 374. See 

 Stimulation 



Trigger action, 262 



Turgor, changes resulting from 

 stimulation, 372 fif. 



Ultra-filtration, 107, 135 

 Ultramicroscopy, 58 

 Ultraviolet rays, activation b}'-, 

 355, Z^2> 



Valence, factor in physical action 

 of ions, gi, 92, 93; factor in 

 physiological action of ions, 92, 

 167 ff., 175 



Visual purple, 266 



Vitalism, 2 



Vitamines, 260 n. 



Water-immiscibility, of proto- 

 plasm, 22, 57 



Yeast, 27 



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