HOW THE LIVING PLANT USES WATER 
83 
water from the plants so that they will become limp 
and will fall down, as shown in Fig. 115, where a ten 
per cent salt solution was poured into the 
soil. After these plants had collapsed, 
tap water was allowed to run through 
the soil overnight, as shown in Fig. 116. 
In the morning the plants had straight- 
ened up again, as shown in Fig. 117, 
because the excess of salt was washed out 
of the soil and the root hairs could then 
absorb water. | 

Fic. 117. After the 
How some stems and petioles remain © gins salt has 
firm. Did you ever think how strong 
been washed out 
of the soil the 
some stems and petioles must be to hold — P!#"*s revive. 
up so much weight as they often do? The leaf of 
the rhubarb is very large, broad, and heavy. 







blade on the end. 
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Fia. 118. 
du) 
The 
leafstalk, or petiole, as we call it, 
is quite soft, yet it stands up firm 
with the great weight of the leaf 
If you 
shave off one or two thin 
» strips from the side, it 
weakens the leafstalk 
|| greatly. Why does the 
"| ~ leafstalk become so 
"Y= weak when so little of 
Leaf of rhubarb before and after chaning oft two the surface is removed ? 
narrow strips from the leafstalk. 
