TRANSACTIONS OF CHAMPAIGN CO. HORTICULTURAL SOCIETY 247 



had been sprouted for preparing mall. In this case the kernels had become dry and no 

 nitrous acid was found. 



The chief interest of this investigation is its bearing on the source of nitrogen in 

 plants. It is well known, as already intimated, that some, like Lieb'eg and Boussing- 

 ault, trace it to the ammonia that enters the plant through its roots, while others, like 

 Ville, contend that it is absorbed l>y the leaves directly from the atmosphere. A potato 

 had been lying several weeks on a table in the laboratory until green sprouts, half an inch 

 or more long, had ajipeared. It occurred to Mr. Gennadius, a student greatly interested 

 in the subject, that if nitrous acid could be found in the sprouts, it would be conclusive 

 proof that it came not from the soil, but from the atmosphere. On examination, strange 

 to say, the sprouts were found thoroughly cliarged with nitrous acid. At first it was 

 suspected that the sprouts had absorbed the acid from the atmosjihere of the labora- 

 tory, to the fumes of which they had been so long exposed ; but on examining sprouis 

 not thus exposed they were found equally charged with nitrous acid. Then it was 

 suspected that possibly the chlorophyl, under the influence of light, had been concerned 

 in its formation; but perfectly white sprouts from any dark cellar give ecpially prompt 

 and decisive indications of its presence, and it is not a little singular that in the potato, 

 in whose stalk and leaves, if we except the tops, little, if any, nitrous acid can be 

 found, should have such an abundance in its sprouts. But this is not all. It will be 

 found by carefully examining the potato, that not only the sprouts but the eyes and 

 the entire epidermis contains nitrous acid, and thai beneath the skin, in the interior 

 of the tuber, not a trace of it can be found ; and if it be examined, as it has been at 

 different periods of its growth, from the time it is of the size of a pea to the full 

 grown tuber, the same will be found true. 



In like manner, nitrous acid is found in the skin of the sweet potato, and in the 

 tuber of the dahlia, while in the interior, at a depth not above the thickness of ordi- 

 nary pasteboard, not a trace of it can be found. We have no doubt the same is true 

 of the Jerusalem artichoke and the ground nut, although we have not yet been able 

 to obtain specimens for examination. In the bulbs of the tulip and the hyacinth no 

 nitrous acid could be detected either in the skin or in the interior. In the root of the 

 African lily, only a trace was found in the skin, none in the interior, and none was 

 found in the root of the peony. It is an interesting fact that in the beet, a j)lant well 

 known to contain an abundance of nitre, no nitrous acid has yet with certainty been 

 found. Also the turnip and the carrot, so far as we have been able to learn, are like- 

 wise destitute of it. It is possible in the case of the beet that the nitrogen enters the 

 plant in the form of nitric acid ; or it may enter as nitrous acid and the condition of the 

 plant be such as to immediately transform it into nitric acid, although the change of 

 nitrous to nitric acid in a plant is far less probable than that of nitric to nitrous acid. 



Now whence comes this acid, and what purpose does it serve in vegetable 

 economy? Does it come from the soil, which, we know, ct^ntains it, and which en- 

 velopes the roots and tubers during the growth, or is it like starch, elaborated in the 

 leaves, from which it passes through the stalk into the tuber, or does it come in part 

 from both sources, or, finally, does it enter the plant as a nitrate and become reduced to 

 a nitrite by the organic matter of the plant, as nitre for example, is reduced to the corres- 

 ponding nitrite by passing through decaying vegetable matter like humus ? So far as 

 one can judge from known facts, the ])roi)ability seems to be that it passes from the soil 

 into the plant, and, like potash, performs an important function in vegetable growth. 

 The fact that little if any nitrous acid is found in the mature leaf of the |)otato, and but 

 little in the stalk, while an abundance is found in the tuber, points to this conclusion. 

 Then the fact that nitrates added to soils produce luxuriant growth caimot well be ex- 

 plained in any other way. 



But few experiments have yet been made with fruits. In the apple, however, the 

 acid is readily detected, particularly in sour apples; and the general fact is that it is 

 most abundant in the interior, particularly in the core, differing in this respect from the 

 potato. Several varieties which have been examined — the Bellflower, Rambo, Smith's 

 Cider and the Fallawater, a large green apple, said to be from Northern Indiana — have 

 all given indications of nitrous acid. It was only in the core, however, that it was found 



