80 THE WORK OF PLANTS 
plump they press against each other and make the 
entire mass of the beet firm and plump. ‘They are 
too tiny to be seen without the use of a microscope, 
but we can look at some pictures of them. 
A dead beet slice cannot work. Place some of the 
fresh slices of beet in boiling water for a few moments, 
or in water near the boiling point. Then test them 
with pressure. ‘They are flabby and bend easily. Place 
them in fresh cold water, and 
in about an hour test them 
again. They are still limp 
y and do not again become firm. 
XS ey f pee Why 1s this? J¢ is because 
| a the hot water killed all the tiny 
membranes in the beet, so that they cannot 
longer do the work. In the living plant, 
then, these tiny membranes are alive. Yes, 
they are alive; and really, they are the liv- 
ing substance of the plant. Usually there 
are strings or strands of the same living 
substance extending across the sac like a 
rough network. The water in the plant, 
with the sugars, salts, etc., dissolved in it, 
Fia.111. Sunflower’. . ° 
seedling fresh. 1: 18 Inside the sac. 
re Why the dead beet slice cannot work. 
When the living substance is killed the tiny membranes 
can no longer hold the sugars, salts, etc., inside them. 



