THE NEW FRONTIER 173 



come to his table is derived from the sugar made in the leaves 

 of plants potato plants and others. A definite number of leaves, 

 whether grown in the fields or in a glasshouse, whether nourished 

 directly by the soil or by the ingredients of soil purified and dis- 

 solved in water to make a nutrient solution, a definite area of 

 leaf surface is necessary for the support of one man for one 

 month." So much for the place the sun occupies in the produc- 

 tion of food for man. And the same nutrient elements which 

 man uses are also used by the plant world in the growth of vege- 

 tation. The nutrition of man and all animal life is merely an 

 incidental function of vegetation. In its entirety, we see all 

 vegetation as a parent material of topsoil, in its eventual break- 

 ing down and disintegration of the earth to form the vital surface 

 layer of homogenized earth. 



Vegetation is bedded in topsoil. Deep into the secret, neces- 

 sary darkness of the earth the roots of plants ramnify, selecting 

 the mineral elements which enter into their structure. Into the 

 air reach the bole and branches, spreading the leaf-green sur- 

 face to the sun; and, through the action of sunlight on chloro- 

 phyll, appropriating the all-pervading nutritional elements from 

 the air. Into the structure of the plant, through the life- forces 

 working in the necessary light of day and working in the equally 

 necessary dark of the night and dark of the earth, are combined 

 the nutritional elements of life in the exact proportions necessary 

 to reproduce the plant. From the parent repository of the air 

 come 95% by weight carbon, oxygen, hydrogen and nitrogen. 

 From the parent repository of the earth come 5% by weight - 

 potassium, silicon, calcium, phosphorus, sodium, magnesium, sul- 

 phur, chlorine, iron, with traces of many other known elements 

 of the universe. To provide a chemical picture of the estimated 

 average composition of the vegetation of the earth, expressed in 

 pounds per thousand pounds of dry matter, we will give a break- 

 down table of the figures. The figures are taken from Soil and 

 Civilisation by Milton Whitney, Chief of the Bureau of Soils, 



