INDEX 



417 



iron, 253 ff., 260, 270 ff., 2q8, 

 382, 385; in plants, 374. See 

 Stimulation 



Trigger action, 262 



Turgor, changes resulting from 

 stimulation, 372 ff. 



Ultra-filtration, 107, 135 

 Ultramicroscopy, 58 

 Ultraviolet rays, activation by, 

 355, 363 



\'alcnce, factor in physical action 

 of ions, (;i, c)2, 03; factor in 

 physiological action of ions, o-\ 

 167 fT., 175 



\'isua! purple, 266 



X'italism, 2 



Vitamines, 260 n. 



Water-immiscibility, of proto- 

 plasm, 22, 57 



Veast, 27 



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