PREFACE 



In' writing' this account of the Rothamsted Experiments — tlie 

 v^ixty years" work of two men, Lawes and Gilhei't, wliose names 

 liave become famihar in every part of tlie world where a«;ri- 

 cuUnre is something more than a matter of tradition and 

 onstom — I am of necessity acting as an external demonstrator, 

 descril)ing from the outside, as it were, what seem to he the 

 chief lessons conveyed by the experiments wliich I have now 

 the honour to conduct. Lawes and Gill^ert are dead, and with 

 them passed away many observations of value and many notable 

 generalisations Avhich they had found no oppoi-tunity of giving to 

 the world, nor had I the personal contact with either which 

 would enable me to report even such portions of their exi)eri- 

 ences as might have been conveyed by conversati(jn. ]>ut 

 though these losses cannot be repaired, and though nothing 

 can replace the instinctive knowledge that comes of having 

 seen a thing grow year after year, yet the position of an t)Ut- 

 sider has some advantages, especially when drawing up an 

 account which, like the present, is addressed to the L'-eneral 

 student of the subject. 



In the first place, the outsider approaches the consideration 

 of each experiment without any of the prepossessions arising 

 from too exclusive a recollection of the purpose with which th<' 

 experiment was originally framed. Headers of the Jioth'ini- 

 ,<-fr(i Mciiio'tr.t will know how certain ideas, r.//., the source and 

 function of the nitrogen in vegetation, occupied the ninid> n| 

 Lawes and Gilbert from the very beginning of their experiments 

 until the end. Tn consequence, the i)apers on .specific invest i- 



