LAWS OF VEGETATION. 77 



New cells cannot be formed without it, and where it is present 

 in considerable quantities, vegetable growth is stimulated to 

 great rapidity. It is supplied to the soil by your barnyard 

 manures, and in small quantities washed from the atmosphere 

 by rain. All those fertilizers which have attained celebrity for 

 producing rapid growths contain it in large proportions. But 

 nitrogen and its compounds are not alone sufficient for the plant 

 to live on any more than sugar will suffice for the only food of 

 man. The other elements of vegetable tissues must be within 

 the reach of the root and the leaf, or all the guano in the world 

 cannot make the plant grow. 



Let us look over a little and see what the plant is made of, 

 how the elements are introduced, and what we can do to supply 

 them. The most important is water. It is important not 

 only because it is the agent by which the solid substances, 

 potash, soda and silica are introduced into the plant, but because 

 it is itself food for the plant, combining with carbon and form- 

 ing most of its solid organic tissues. It consists of eight parts 

 of oxygen to one of hydrogen, and in all the organic com- 

 pounds of tlie vegetable, oxygen and hydrogen exist in the same 

 proportion, and we therefore say they combine as water, or that 

 water is not resolved into its elements in combination. Woody 

 fibre when dry, contains, by weight, equal parts of carbon and 

 water, seventy-two parts of the one and seventy-two parts of 

 the other. Cane sugar contains seventy-two parts of carbon 

 and ninety parts of water. Starch has the same composition. 



The earthy ingredients are deposited in the cells and are 

 necessary to the strength and growth of the stem and the per- 

 fection of the seed, fitting them for the food of animals and 

 man. In every ton of red clover hay which you cut from the 

 field, there are forty pounds of potash, eleven pounds of soda, 

 fifty-six pounds of lime, eighty pounds of silica, nine pounds of 

 oil of vitriol, thirteen pounds of phosphoric acid, and seven 

 pounds of chlorine. In every ton of clover hay you cart from 

 the field you cart away one hundred and fifty pounds of these 

 mineral substances. And tliis is done year after year, not only 

 in your hay, but in your corn, your oats, and your rye. Whence 

 come these elements to supply the perpetual demand made 

 upon them by the annual cropping ? Do they exist in the soil 

 in such quantities that they never become exhausted ? I will 



