Lecture 4 



87 — Movement and Distribution 



concentration of bromide reached that of the outside 

 solution. The curve for the nitrogen treated plant 

 gave evidence only of a slight upward trend in the 

 time allowed. Volumes of liquid moved through the 

 roots under suction, per unit time, also were affected 

 in a somewhat similar manner. 



TIME 



Textfigure 24. — Movement of Br into internal 

 solution obtained by suction applied to stem of to- 

 mato plant. Roots of plants under several condi- 

 tions: I, aerated, II, free Nj gas bubbled through 

 solution, III, CO2 gas bubbled through solution. 

 (From HOAGLAND and Bboyer, 1942). 



One way to interpret these results is to assume 

 that the absence of oxygen, or the high concentration 

 of carbon dioxide, caused loss of power of salt ac- 

 cumulation and at first a decrease of cell permeability, 

 followed, however, by a breakdown of protoplasm 

 and subsequent increase of permeability, but without 

 any capacity on the part of the cells to secrete salt 

 against a concentration gradient. The injurious effect 

 of the carbon dioxide treatment is particularly evident 

 and gives rise to a condition in which the unconcen- 

 trated salt solution is more or less readily drawn 

 through the root system. With regard to the volume 



