MISCELLANEOUS PAPERS. 263 



life. But if a plant can grow and ripen seed in the entire absence of another 

 ash element, then such substance is excluded from the list of essential ash 

 elements, no matter how much its presence may increase tlie vigor of growth 

 and development of the plant grown under natural conditions, or how much 

 of the substance is usually found in the ash of such plant. The chemist sim- 

 ply asks, "Will the plant live and ripen seed?" while the farmer asks, ''How 

 large will it grow?" 



ESSENTIAL AND ACCIDENTAL ASH ELEMENTS. 



The question whether the substance was essential to plant growth could not 

 be settled by growing plants in ordinary soils, because the "essential" and 

 "accidental" ash elements are found associated in every fertile soil. To an- 

 swer this question we must place a plant in a soil or medium for growth from 

 which the substance under consideration is rigidly excluded. For this purpose 

 Prince Salm-Horstmar, of Germany prepared an artificial soil, composed of 

 powdered flints, purified sand, and charcoal made by burning loaf-sugar. To 

 this soil, containing nothing but silica and carbon, he added all the usual ash 

 elements save one, planted the seed of some plant, supplied all the physical 

 conditions of plant growth, and then watched the results. Each one of the 

 ash elements in turn was excluded in his experiments. 



WATER CULTURE. 



Later investigators have dispensed -with a soil altogether, and raised plants 

 by "water culture." The seed is sprouted in damp cotton or between folds 

 of wet paper till the roots are well developed, when the plant is suspended so that 

 only the roots dip into water which contains in solution or suspension the ash 

 elements to sustain the plant. By careful treatment plants have been grown 

 to large size and full development by water culture. In this way one ash ele- 

 ment after another has been excluded from the nourishing solution, and the 

 results carefully watched. While potash, lime and magnesia were essential 

 for the development of a plant from a seed, the question arose whether soda 

 was essential. Prince Salm-Horstmar, as the result of numerous experi- 

 ments u})on wheat, oats and barley, concludes that in the early vegetative stages 

 of growth, soda, while advantageous, is not essential, but that for the perfec- 

 tion of the seed an appreciable though a minute quantity of soda is indispensa- 

 ble. On the other hand, several experimenters have succeeded in bringing 

 maize to complete perfection by water culture in which no soda salts were 

 used, and they claim that soda is not essential. Yet no one has raised a plant 

 in which soda was not found in some part. All admit that chlorine is essential 

 for ripening the seed of some plants, such as buckwheat. 



When the German chemists exclude soda from the list of "essentials" for 

 plant growth, are we to conclude that it is therefore of no value in agriculture? 

 A farmer has a long list of implements Avhich are not essential for farming, 

 because farming has been, and may still be, carried on without them ; the 

 mower and reaper, tiie horse-rake, the cultivator, the roller, and a score of 

 other things are not essential to farming, but the farmer does not discard 

 them on that account, because he can raise enough more on his farm with 

 these implements to more than pay for their use. In the same way do not 

 reject salt as a manure, as many writers on theoretical agriculture have done, 

 simply because, in a narrow and limited sense, it is not essential to plant life. 

 It may be very beneficial even if it is not essential to plant growth. This 

 brings us face to face with many important questions in regard to salt as ma- 



