454 



Scientific Proceedings, Royal Dublin Society. 



The three upper graphs iu tlie figure show that the depression of freezing 

 point and the osmotic pressure of the sap of the thicker roots are constantly 

 greater than those of the thinner ones. The grapli for the mixed samples 

 shows that the pressure rises fairly steadily through the winter, spring, and 

 summer. At the end of the summer it rises abruptly to a maximum (nearly 

 14 atm.) iu September, and then drops even more suddenly to its winter 

 condition (6-7 atm.). No concentration with age could be discovered in 

 the electrolytes. As will be seen, the concentrations of the electrolytes 

 determined iu the three sets of samples cannot, as in the case of the total 

 solutes, be separated into tliree groups. Apparently the concentration of 



