THE SOUECES OE THE NITKOGEN OF VEGETATION, ETC. 



513 



rimcnts it was found that plants which had proceeded for some time in this delicate 

 form of growth, immediately ceased this predominant upward tendency when removed 

 into sunlight : then, after remaining stationary for a few days, during which time the 

 extremities of the long delicate leaves lost their vitality, the plants commenced a new 

 order of growth, producing many more leaves, which were much shorter and broader 

 than the earlier ones; the stems also became thicker and more dense than before. 



The seeds were put in on May 17 (1858) ; and on June 10 following, the plants had 

 ceased to grow. Several of the long slender stems were too delicate to support them- 

 selves, and began to fall over. All the plants presented much the same appearance, 

 each with a small sheath without any leaf at the base, and three leaves higher up — the 

 two lateral ones being very long, from 8 to 12 inches, and the terminal ones, not unrolled, 

 from 3 to 4 inches long from the axial of the next leaf below, the whole plant being from 

 7 to 11 or 12 inches high. On removing them from the soil, it was found that the roots 

 were distributed very little through it. They consisted of short fibrils, with divaricated 

 branchlets, extending principally around the seeds, and seldom more than 2 or 3 inches 

 through the soil. The plants were so very much alike, that it was difficult to distinguish 

 the different kinds. Fig. 9, Plate XII., is reduced from a sketch of one of these atten- 

 uated plants. 



The following Table gives the quantitative particulars of the experiments. 



Table XL — Showing the effect of Germination, and Growth without direct Sun-light, 

 or extraneous supply of Carbonic Acid or combined Nitrogen, upon the combined 

 Nitrogen originally provided in the Seed. 



Duration of experiment twenty-four days — from May 17 to June 10, 1858. 



The weights given for the roots are a little too high, owing to their not having been 

 washed entirely free from soil, the principal object being to ensure a correct result with 

 regard to the Nitrogen which long washing might have endangered, or at least rendered 

 less easy. There is, however, evidently a slight gain of dry matter, which, so far as its 

 carbon is concerned, was doubtless due to carbonic acid in the distilled water, of which 

 about 500 cub. cent, were added to each pot at the commencement of the experiment. 

 None was added during the progress of the experiment ; but the soil was moist when 

 the plants were taken up. 



The rapid growth of the plants, the short period of their contact with the soil, the 



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