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OSMOSIS AND TURGIDITY 



The gardener finds it easier to cut weeds with his hoe in the early morning, when 

 the plants are turgid and brittle. Farmers plan to use the rotary hoe on young grow- 

 ing corn after the plants have wilted slightly, as otherwise the fingers of the hoe 

 would break the plants 



place the ends of celery stalks and of other leafy and root vegetables in cold 

 water, and store them in a cool place, to keep them from wilting — that is, 

 to retain their crispness. 



The turgidity of plant tissue holds stems and leaves up, even where there 

 is little mechanical or fibrous tissue present. This is especially noticeable in 

 the spring, when rather tender tissues push through the ground in their 

 rapid growth. At the same time, these turgid stalks are easily broken, as 

 every farmer and gardener knows (see illustration above). 



How Do Living Things Adjusf Themselves to Changes in Water Supply? 



Adjustments The dryness or wetness of the environment varies in the 

 course of the day, from day to day, from season to season, and from place 

 to place. Marine organisms living along the shore experience alternate dry- 

 ness and wetness with each change in the tide. Only plants and animals 

 that live continually in deep water escape the seasonal variation in their 

 environment. Land plants and animals that are exposed to drying condi- 

 tions have, as a rule, coverings that prevent the rapid loss of water. Our own 

 skin separates the marine-like interiors from dry and variable conditions 

 outside. 



89 



