ASPECTS OF SALT ABSORPTION IN CELLS 



109 



chloride, chloride is absorbed. If salt is supplied in this way to only 

 part of the leaf segment (absorption zone) transport to other regions 

 can be examined. It was observed that when the absorption zone is 

 illuminated, chloride tends to accumulate in that area, and little is 

 transferred elsewhere especially when the rest of the leaf is kept in 



200 



I 50 



100 

 en 

 ^ 50 



o 



Q. 



O 

 en 



.O 

 O 



I 



Solt 



D D 



DLL 



Salt 



(a) 



(b) 



(0 



Salt 

 + DNP 



(d) (e) 



L L L 



Salt 

 ♦ DNP 



(f) 



O 



80 



AO 







DLL L L L 



jp c=i cp 



1 T 



IT 



Solt + KCN Salt+KCN Salt+DNP Salt 



KCN KCN 



¥ 



1 



Sol 



DNP 



Cell wa 



Symplast 



Vacuole 



Fig. 37. Absorption and transport of chloride in Vallisneria leaves (redrawn 

 from Arisz, 1953). a-k O Effects of light and metabolic inhibitors on accumul- 

 ation of chloride in different zones of leaf segments L=zone exposed to light; 

 D = zone exposed to darkness; KCN = potassium cyanide (3xlO"^M); 

 DNP = dinitrophenol (10=*M); Lower diagram summarises the interpretation 

 of a-k-/o%location of an absorption mechanism sensitive to cyanide x 

 location of a mechanism sensitive to dinitrophenol, and stimulated by light. 



darkness (Fig. 37abc). Darkening the absorption zone when the 

 rest of the leaf was illuminated reduces accumulation in that region 

 and promotes transport elsewhere (Fig. 37d). These resuhs were 

 explained on the assumptions that absorption of salt by a vacuolated 

 cell is a two-stage process involving, firstly, entry into cytoplasm 

 and secondly transference into the vacuole, and that cell to cell 

 transfer occurs through the cytoplasm (Fig. 37). Illuminated cells 



