23 



Professor Johnson says: < The great deserts of 

 tin* world are not sterile because they cannot yield 

 the soil-food required by vegetation, but because they 

 ;uv destitute of water." 



Ik i also says : u Poor Foils give good crops in sea- 



of plentiful and well distributed rain oj when 



skillfully irrigated, but insufficient moisture in the 



soil is an evil that no supplies of plant food can 



neutralize." 



The cause of this will be plain, on a moment's re- 

 hVetion. Plants can only take up their food in a fluid 

 condition, 



Mr. Lawes proved that an acre of wheat in five 

 months and eighteen days evaporated through its 

 leaves .'J-'ioJ tons of water. Now every drop of this 

 water was more or less instrumental in transporting 

 a little atom of focrd from the soil to some part of the 

 plant, and when the deposit was made,, being no 

 longer needed, the water passed off through the 

 leaves. 



Liebig also teaches this doctrine. Re says : 

 " Though the soil be ever so rich in the elements of 

 food for plants, still the latter will not grow in hot 

 weather if there be a deficiency of moisture in the 

 soil, for the moisture in the soil is the channel 

 through which mineral food has to reach the interior 

 of plants." 



The reader who has not been a careful observer of 



the changes in nature, and the amount of rainfall, 



after year, will be very likely to suppose, that 



drouth is a plague that very seldom visits our much 



favored land, and hence he may consider it useless to 



