SUMMARY 6l 



region from the irrigated root. Irrigation with warm water 

 reduces the latent period. 



Diminution of turgor caused by withdrawal of water 

 depresses the rate of growth. 



Artificial increase of internal hydrostatic pressure up 

 to a critical degree enhances the rate of growth. 



The law of the directive movement of sap (which induces 

 change of turgor) is that it follows the stimulation-gradient 

 from the stimulated to the unstimulated region. 



There is a correspondence between the responsive 

 movement of the leaf of Mimosa and the movement of 

 growth. An increase or positive variation of turgor, due 

 to enhanced rate of ascent of water, induces the erection or 

 positive response of the leaf of Mimosa, and the positive 

 variation or enhancement of the rate of growth. A diminu- 

 tion or negative variation of turgor, due to withdrawal of 

 water, induces the fall or negative response of the leaf of 

 Mimosa, and the negative variation or retardation of the 

 rate of growth. 



External tension, within limits, enhances the rate of 

 growth. 



