PERSONALITY OF PLANTS 
makes their soft bodies rigid and so makes 
movement possible. This property sometimes 
called turgidity was discovered by the scientist 
De Vries in 1877, the same year that Pfeffer 
established the theory of osmosis. This latter 1s 
a phenomenon which physicists find very dif- 
ficult to explain and involves the transmuta- 
tion of one liquid into another through the me- 
dium of an intervening membrane. 
Some plants have aquired the faculty of stor- 
ing water in their bodies, on which, camel-like, 
they can subsist for long periods of time. A 
certain large tree-cactus of the American desert 
sometimes stores up as much as seventeen hund- 
red pounds or five barrels of water in the wet 
season. When drought comes, its roots dry up 
and it lives entirely on its internal resources. 
It is said that an eighteen-foot specimen can 
exist for a year on its stored-up liquid. A 
branch on such a plant may live and bloom after 
the trunk is dead. Many ordinary plants, such 
as Turnips, Carrots, and Beets, store water 
along with starch and dextrose in their under- 
ground tubers. Such subterranean reservoirs 
are preferable to those above ground. 
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