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XXII. On the Sources of the Nitrogen of Vegetation; with special reference to the 
Question whether Plants assimilate Free or uncombined Nitrogen. By Joan Bennet 
Lawes, /.2.S., F.C.S., Joseph Henry Ginpert, PA.D., F.RS., F.CS., and Evay 
Puen, PA.D., FCS. 
Received June 21,—Read June 21, 1860. 
Contents. 
PART FIRST. 
GENERAL HISTORY, AND STATEMENT OF THE QUESTION. 7 
age 
Section I.—Introduction, and carly History .ic.ccssscecsccssscccssscnccenssaceececseasensescssseeesease 433—435 
Szotion Il.—Annual yield of Nitrogen per acre, in different Crops :— 
A. Yield of Nitrogen per acre when the same crop is grown year after year, on : 
the same land .......cseseeeeee 435—438 
B. Yield of Nitroaen ner acre shel Wheat di is ow in jalieeaa tion: with “Hoang, 
or with Fallow  ......ssccseeeee ey . 438—439 
C. Yield of Nitrogen per acre when rea are 2 grown in in an agebual 2 course ve: Rotation 439—440 
D. Relation of the increased yield of Nitrogen in the produce, to the amount sup- 
plied, when nitrogenous manures are employed .........cessececeeeeseceeeereeeces A40—442 
Section III.— General view of the various actual or possible sources of the Nitrogen of our crops :— 
Enumeration of, observations, GC. ..csscccccsscseseecccescscecevessecscsevcccsessssessesssrsee 442—44.7 
Section IV.— Review of the Researches of others, on the question of the assimilation of Free 
Nitrogen by Plants, and on some allied points :— 
Iniroductory observations ........... ie due use Velo Wainssehie es dentaesicnnais sonemmeee. AAT 
A. The Experinients of M. Bovesureavur sasived dns ddaseayasmemnvasiey ceacauinainee ans Kanu 448—455 
B. ‘The Beperintente of MT Gi VIUie civics coswsoasnndewennviinntionncasons ene tty tdeesean 455—463 
Summary statement of the Results, and conclusions, of M. Bousstr@avtt, and 
C, The Pepeineais of M. Mins . sad maNbass Fone aeaN te Tse TET TREND IT ATs eaeeecene  “AOM 
D. The views of M. Ror.. was iibeidieriaiin wees AB4—465 
E. The Experiments of MM. Chow aud “G@RATtOzeER .. jitoniees den aecerawnemenase AO 
¥, The Experiments of M. Dz Luca... dwiseitioaupases seeuansiions wexesvieivebiesnwes 260—466 
G. The Experiments of M. HamrinG .....cccccscssecsecesssecneteeceecesasecseeseeecesens 466 
H. Experiments recorded by M. A. PETZIMOLDT ....scseeccavecseseseverscesonessesecsscee 467 
Concluding observations .......ccesesecsesseeeesseneeeesseseetecssscsees secesseeessccses 467—468 
PART SECOND. 
EXPERIMENTAL RESULTS OBTAINED AT ROTHAMSTED, DURING THE YEARS 1857, 
1858, AND 1859. . 
Lntroductory ODServations vessecrsecrrennteaserssscrensaceesessessrsetsssessscsssssssrscesserssssssesetsesses  468—470 
Srcrion I.—Conditions required, and Plan adopted, in Experiments on the Question of the assi- 
milation of Evee Nitrogen by Plants :— 
A. Preparation of the soil, or Matrix, for the reception of the Plant, and of the 
nutriment to be supplied to it ....cccsscscescsssccnseonccateveecccesessesenssssesesenes 470—472 
MDCCCLXI. 30 
