162 [SOME RECENT RESEARCHES IN PLANT PHYSIOLOGY 



sures. In this connection, the experiments on Ilex (Dixon 

 and Atkins, 1915, 2) are of interest. They show that the 

 pressure increases with the size of the root, whereas the 



ILEX AQUIFOLIUM ~Roots. 

 FIG. 19. 



The upper curves, A. B, and C, show the depressions of freezing-point and 

 osmotic pressures in atmospheres of thick (over 2 millimetres in dia- 

 meter), thick and thin, and thin roots respectively. The lowest 

 curve shows the pressures due to electrolytes. In this case the 

 size of the root is immaterial, as the individual determinations of 

 the three kinds lie on the same curve. 



electrical conductivity only fluctuates slightly, as may be 

 seen from Fig. 19. The meaning of this appears to be 



