LOSS OF WATER 



41 



becomes a real source of danger to the plant. Indirectly, 

 however, transpiration performs a great service, for it 

 aids in, and is probably one of the chief causes of, the 

 ascent of liquids taken in from the soil. Were water 

 never given off, (either by transpiration or by secretion or 



Fig. 32. — Sempervivum tabidcBJorme. The arrangement of the leaves 

 in a compact rosette, the hairs on their margins, their thick cuticle, and 

 other characters, make the plant xerophytic or drought-resistant. 



both, see paragraph 41) it would not be possible for tissues, 

 already turgid, to receive a fresh supply, and, since all the 

 elements of plant-food can be carried through the plant 

 only in solution, the importance of this point can hardly 

 be overestimated. 



The manner in which transpiration may facilitate the 

 passage of liquids through the stem may be illustrated 



