440 POPULAR SCIENCE MONTHLY. 



per cent. Thus it was proved by him that fresh leaves fallen from 

 trees absorb atmospheric nitrogen in the process of decomposition. 



The two other boxes remained exposed to the air for another 

 year, and in May, 1896, fifty grams of fine forest soil were added to 

 each box. On subjecting the leaves contained in them to a chemical 

 analysis, Professor Henry found almost the same contents of nitrogen 

 that had been found in the leaves of the first two boxes which were 

 exposed to the air during only one year. From these results he 

 concluded that the capacity of fallen leaves to absorb nitrogen from 

 the air is retained only in leaves freshly fallen on old litter. 



The capacity of forest litter to absorb nitrogen develops probably 

 under the influence of special microorganisms, active only at the 

 beginning of the process of decomposition of fallen leaves; later, 

 however, when the process of decomposition of leaves goes on under 

 the influence of exclusively inorganic agents, no increase of nitrogen 

 i? observed; on the contrary, a loss is shown. 



It is thus scientifically proved that forest litter is capable of 

 enriching the soil with nitrogen, but only under the condition that 

 the decomposition of freshly fallen leaves goes on. As to the assum- 

 tion that bacteria are developed in freshly fallen leaves, which, like 

 BMzobium leguminosarum Frk., possess the capacity of absorbing 

 atmospheric nitrogen, it can only be said that as yet no bacteria 

 have been found in forest litter. 



A practical deduction from Professor Henry's scientific investi- 

 gation is the advisability of planting cut-over areas as soon as possible, 

 so that the young seedlings may find in the soil a quantity of nitrogen 

 sufficient for their nourishment. The longer cut over areas remain 

 unplanted, the less is success to be expected from planting, as the 

 young trees develop poorly because of insufficient nourishment. 



Thus, the forest not only furnishes timber and other products, 

 prevents snow- and land-slides, and regulates the flow of rivers, but 

 enriches the soil with nitrogen, one of the most essential nutritive 

 elements of plants, and in this way transforms poor soils, fit only 

 for tree growth, into rich agricultural lands. 



