Physiological Anatomy of Xerophytic Selaginellas. 131 
weight after complete absorption of water from 42 to 54 per cent. 
Xerophytic Selaginellas contain in their cells a considerable 
amount of oil; it is to be found in small drops in the protoplasm ; 
when the cell loses water and the protoplasm shrinks, the drops 
unite and become larger, which suggests that a film of oil forms 
around the entire protoplast during drought, when it is able to 
enter its dormant state. Hygrophytic species do not produce oil, 
but starch, and this suggests that oil is also a reserve food for the 
xerophytic species, which produce less starch. 
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A 
