Roots 11^ 



taking away by evaporation almost pure water. The 

 salts, therefore, accumulate, and sea water is salt and 

 bitter in consequence. 



The salts left in a plant do not usually make it salt or 

 bitter, because the quantity is altogether extremely minute 

 in proportion to the plant's size; and as they are dis- 

 tributed through the whole of its substance, there is a 

 continual demand for them while the plant is growing or 

 putting forth fresh leaves. 



But if a plant is stunted by drought it may become 

 actually bitter. A cabbage, for instance, which has not 

 reached perhaps a quarter its proper size for want of 

 water, will be quite bitter; and the reason seems to be 

 that the salts, which would have been enough for a large 

 cabbage, are compressed into a very small one. Or, in 

 other words, the roots have not been able to find enough 

 water to dilute the food which they have gathered, as well 

 as to keep pace with the transpiration of the leaves, and 

 to allow of their proper growth. 



QUESTIONS FOR REVIEW 



1. Show how soils vary in their ability to suck moisture 

 from the air or to keep it. 



2. How do soils differ in their readiness to give up moist- 

 ure? Illustrate. 



3. How is the surface soil moistened in time of drought? 



4. How do the roots vary in different kinds of plants? 



5. Describe the character of a root. 



6. Why is it necessary that soil should be both fine and 

 well mixed? 



7. Why is clay a poor soil for plants? 



8. What is the character of the water taken up by the roots? 



9. Why is the sea salt? 



