VI PREFACE 



of the natural processes with which they come into 

 contact daily. 



The work embodies the results of much experience 

 in the scientific training of students, and deals with most 

 of the points which the author considers of fundamental 

 importance in the study of bacteriology, so far as the 

 requirements of the farmer and gardener are concerned. 



I shall be grateful for any suggestions for improving 

 the work. 



My thanks are due to Miss Grace Heather Mason 

 for assistance in carrying out the work of the practical 

 exercises and also for help with the index and proofs. 



JOHN PERCIVAL 

 May 1910. 



