HOW THE LIVING PLANT USES WATER T9 
How the beet slice works. ‘The beet slice is not like 
a bladder membrane, but some of the substances in the 
beet act like the sugar solution inside the vial. In 
fact, there are 
certain sugars 
and salts in 
solution in the 

beet, and it is 
5 », iG. 109. Picture of a real plant cell, at left it is in natural 
t h e€ pu 1] condition, middle one after lying in a salt solution, one at 
right after being taken from salt and placed in water. 
which these 
exert on the water outside that makes the beet rigid. 
While these sugars and salts in the beet draw the water 
inside, what is there in the beet which acts like the blad- 
der membrane through which the water 1s “ pulled,” and 
which holds it from flowing quickly out again? In the 
beet slices there are thousands of tiny membranes of a 
slimy substance in the form of rounded sacs, each lining 
a tiny box. Every one of these forms a plant cell, and 

Fig. 110. Cells of beet slice, at left fresh, middle ones just placed in salt water, 
ones at right after lying in salt water a few moments. 
acts like the bladder membrane in the make-believe cell. 
Inside these tiny membranes the sugars and salts of the 
beet are in solution. When the cells are full and 
