76 LUTHER BURBANK 



the constitution of the soil the very existence of 

 the soil itself is of incidental or subsidiary sig- 

 nificance only in the plant economy. The richest 

 soil that was ever prepared would not grow a 

 single blade of grass or the tiniest weed if that 

 soil were absolutely dry. 



Nor could the hardiest weed maintain exist- 

 ence for a single day if transplanted into a soil, 

 be it ever so rich, that is absolutely devoid of 

 moisture. 



There must be water in the soil, to dissolve out 

 and transfer its elements, in order that the root- 

 lets of the plant shall be able to make the slightest 

 use of these elements. Every essential con- 

 stituent of plant food may be present in just the 

 right proportions in soil that is packed about the 

 roots of the plant with just the right degree of 

 firmness, and yet the plant would perish as in- 

 evitably as if it were uprooted and suspended in 

 the air, if there were not water present to bring 

 the food materials into a state of solution. 



But, on the other hand, as we have seen, a plant 

 may grow and thrive for a time quite without the 

 presence of soil if its roots are placed in water. 



If we look a little farther into the intimate 

 structure of the plant, utilizing the knowledge 

 gained with the aid of the microscope and the 

 studies of the chemist, we shall quickly come to 



