PLANTS. 53 



through their leaves than they do from the ground 

 through their roots. The substances taken up by 

 the roots are very essential, though small in amount. 

 Water in the soil contains dissolved substances 

 which are taken up and used by plants. They 

 have the power of selection, to a certain extent, and 

 exclude some things which are not conducive to 

 growth. Some things, however, are taken into the 

 plant structure by the roots which either retard 

 growth or cause the plant to die. Common salt, 

 for instance, when dissolved in water will kill most 

 plants very quickly. It can be seen from this that 

 right kinds of food should be in the soil, and that 

 injurious substances should not be, if strong and 

 vigorous plants are to be grown. Certain elements 

 are necessary for the growth and development of 

 a plant. If they cannot be secured, the plant will 

 die. 



WHY PLANTS HAVE SO MANY ROOTS AND LEAVES. 



All plant food must be dissolved in water before 

 it can be taken up by the roots. They have not 

 the power of eating solid food as animals have. 

 Instead of one large mouth, they have thousands of 

 small mouths. These mouths are so small that 

 they cannot be seen with the naked eye, hence 

 solid food cannot enter them. Then, too, the food 

 in passing up the stem and out to the leaves 

 through the branches does not flow through a 

 large tube like the digestive tract of an animal. It 



