PREFACE ix 



the growth of plants, maintain for bacteria. The 

 work of Professor Bottomley opens up an oppor- 

 tunity for every gardener and for every farmer to 

 undertake important scientific work, and at the 

 same time almost certainly to increase very con- 

 siderably the yield from his land. Such work is of 

 the very first national importance and of world-wide 

 interest. It is certain that one of the most 

 important factors in the fertility of all land is the 

 nature of the bacteria in the soil. In every depart- 

 ment of life man, by assisting Nature, has been 

 generously rewarded. The science of bacteriology 

 both in medicine and in the arts has very richly 

 repaid the labour spent on it. It is inconceivable 

 that horticulture and agriculture should prove 

 exceptions to the general rule. 



In the preparation of this book I have to acknow- 

 ledge much assistance. To Professor Bottomley 

 and his writings I am indebted exclusively for my 

 knowledge of his work and for the major part of 

 what I know about the subject in general. During 

 the years that I have known him he has at all times 

 given me access to his laboratory and to the reports 

 that have been sent in to him. Throughout he has 

 inspired, read, and criticized the manuscript of the 

 book. I also owe much to Mr. Alfred Machen, who 

 has shown and explained to me many of the experi- 

 ments now in progress on the land. The chapters 

 on the General Results from the use of humogen, on 

 the Application of Humogen, and the practical hints 

 in conclusion, are due entirely to him. Miss Mocke- 

 ridge, by her valuable criticism, has saved me from 



