BULLETIN OF THE BUSSEY INSTITUTION. 267 
purposes, grew barley in the one case, and barley, wheat, and beans in 
the other, in pots of garden-earth that were watered with water that 
had been thoroughly freed from nitrogen compounds. ‘These investi- 
gators obtained luxuriant crops from their pots of garden-earth, though 
the plants grown in this earth got no nitrogenous food beside that ° 
naturally contained in the soil. In the experiment of Lawes, Gilbert, 
and Pugh, the earth and plants were even shielded from the ammonia of 
the air, which was formerly supposed by some chemists to be suflici- 
ently abundant to exert an appreciable influence upon the growth of 
plants. 
It is remarkable that so little attention has been paid, of late years, 
not merely to these experiments, but to the great general fact, which 
has in reality long been known, that plants can in some way obtain a 
great deal of nitrogenous nourishment from the vast stores of nitrogen 
that are contained in the humus of the soil.* For from the moment 
when the fallacy of the notion that there is ammonia enough in the 
soil and air and rain to support the growth of wild plants of the higher 
orders had once been generally recognized and admitted, there has 
been urgent need not only of a true explanation of certain facts that 
had formerly been considered as part and parcel of the erroneous 
* It was shown long ago by the analyses of Krocker (‘‘ Annalen der Chemie 
und Pharmacie,” 1846, 58. 881), and those published in 1849 by the Prussian 
Lamles-eekonomiecollegium (cited in ‘ Die landwirthschaftlichen Versuchs- 
Stationen,” 1861, 3. 214), that cultivated soils rarely contain less than 0.10% of 
their weight of nitrogen, and often much more. A. Miiller (see Hoffmann’s 
“ Jahresbericht,” 1862, 5. 46, and 1866, 9. 35), as the result of the examination 
of a considerable number of Swedish soils, found on the average 0.66% of nitro- 
gen in the surface-soil of limestone regions, 0.26% of nitrogen in the surface- 
soil of regions poor in lime, and 0.15% in the subsoils of the latter. In several 
instances he found as much as from 0.90 to 0.96% of nitrogen. The proportion 
of nitrogen in the organic matters of these soils was on the average 4.6% in the 
case of the soils from limestone regions, and 3.7% in the soils poor inlime. The 
results of Miiller are surprisingly similar to those obtained subsequently by 
Grouven (Hoffmann’s “ Jahresbericht,”’ 1867, 10. 35) in his analyses of a large 
number of German soils, fit for the growth of sugar beets. See, further, 
Hoffmann, in his “ Jahresbericht,” 1859, 2. pp. 51-57. In the remarkably fer- 
tile “ black earth ” of Russia, Krocker found, in one instance, 0.4% of nitrogen, 
and E. Schmid (See Liebig & “Kopp’s ‘‘ Jahresbericht,” 1849, 2. 660) from 0.33 
to 0.997%. In 30 samples of American peats, Johnson (‘‘ Peat and its Uses,” 
p- 83) found from 0.4 to 2.9% of nitrogen. In 11 analyses of European peats, 
collated by Websky (Hoffmann’s “ Jahresbericht,” 1864, 7. 7), the percentage 
of nitrogen ranges from 0.77 to 2.59. 
