PREFACE 



THE science of bacteriology, which has been so much 

 the domain of the student of disease, is now being 

 applied to the elucidation and solution of many of the 

 problems which confront the farmer, gardener, and dairy- 

 man in their daily life. 



The extensive development of the dairying industry 

 has been greatly assisted by the bacteriologist, and very 

 material advances may be expected in the near future in 

 the application of the science to the study of the soil 

 and the phenomena connected with the economical and 

 efficient use of fertilisers for the nutrition of farm and 

 garden crops. 



For some time a knowledge of bacteriology has been 

 demanded of candidates for examinations in agriculture, 

 dairying, and horticulture, but experience has shown that 

 few of them have had any practical acquaintance with 

 the subject, mainly, we believe, from lack of suitable 

 opportunities for proper training and absence of a text- 

 book dealing with the subject in a practical way. 



It is to supply the needs of such students that the 

 present text-book has been written. It is hoped also 

 that it will be useful and interesting to agriculturists and 

 horticulturists generally who are anxious to obtain an 

 insight into the causes and methods of control of many 



