384 STATE BOAKD OF AGRICULTURE. 



the work. I make the following extract from my experimental note book : 

 March 3cl, 1882. " Experiments to determine the source of nitrogen of plants, 

 and in particular to determine whether the inert nitrogen of the humus of soil 

 may serve as a source of nitrogen for clover and other leguminous plants, and 

 whether cereals can obtain their supply of combined nitrogen from the same 

 source. 



"In these experiments I propose to use clean sand as the mechanical 

 element of my experimental soil, the sand having previously been ignited so 

 as to expel all forms of combined nitrogen ; swamp muck to represent the 

 humus of soils; freshly ignited wood-ashes and a pure superphosphate of lime 

 to represent the mineral elements of plant growth ; the soil for each kind of 

 plants to be placed in new and clean flower-pots (7-inch pots), these pots to be 

 kept in a glazed room screened from rain and dew, but freely exposed to the 

 air; the plants to be watered with distilled water, free from ammonia." Sub- 

 sequent examination of the distilled water showed a small amount of ammonia 

 (one part in 10,000,000). As my experiments were to be differential rather 

 than absolute, and the amount of ammonia conveyed to each plant would be 

 substantially the same, I disregarded the ammonia accidentally present. The 

 superphosphate was made by burning bones white, decomposing the bone-ash 

 with pure sulphuric acid and neutralizing excess of acid by caustic potash. 

 Aside from the small amount of ammonia in the distilled water, and the 

 known amount of nitrogen in the seed, the plant during growth was thus cut 

 off from all nitrogen except the air supply and the nitrogen of humus, but at 

 the same time was supplied with all the other chemicals of agriculture. In 

 most of the experiments the seeds were sprouted in clean moist sand, in order 

 to eliminate any possible supply of nitrogen from decomposition of seeds that 

 failed to grow. lu most of the pots four seeds were planted. Probably I 

 would have secured better results if I had raised only one plant in each pot. 



My first set of experiments were almost a total failure on account of using 

 too large quantity of wood-ashes, but a new series was started at once with new 

 pots and filling. 



Three kinds of plants were used : Medium red clover, wax beans, and Claw- 

 son wheat. The clover seed was very small, 630 seeds weighing one gramme, 

 or very nearly 40 to the grain; four wax beans weighed one gramme, and 23.4 

 grains of wheat weighed one gramme. Seeds planted May 6, and gathered 

 for examination August 8. 



PLANT DEVELOPMENT. 



Wheat. In the early stages of growth the wheat plants came forth with 

 vigorous growth, giving promise of outstripping all the others. This contin- 

 ued till the store of plant food in the seed was entirely exhausted, when 

 growth was somewhat checked; many became spindling and sickly, unable to 

 support the partly developed stem which reclined on the soil, were attacked by 

 fungi, and about one-half died before the close of the experiment. Of those 

 that survived, the upper leaves remained with some vigor of growth, while the 

 lower leaves withered. The best pot of wheat plants was taken as the repre- 

 sentative, — four plants; two of these had two stalks each, and two only one 

 stalk each; the roots had made a firm mat all around the inside of the pot, 

 but most abundant at the bottom; two or three nodes in the stalks but no 

 formation of head, development seeming to have been arrested when the head 

 should form. The four plants when washed clean and dried in steam bath 



