PREFACE 



TO THE SECOND EDITION 



SOME twenty years ago, when the first 

 edition of this little book was issued, bac- 

 teriology was in its early infancy. It is an 

 infant still, but grown more lusty and articu- 

 late. These minute plants, the bacteria, 

 logically belong in the purlieus <jf the botanist. 

 But he has always turned the cold shoulder to 

 them. 



So at first they were popularly regarded as 

 the foster children of Medicine. But little by 

 little, the arts and the industries and the 

 farmer have found them out so that to-day 

 this modest bailiwick of the biological sciences, 

 which we call bacteriology, is held in trust 

 by a syndicate of scientific folk, of whom 

 the medical men are perhaps the most con- 

 spicuous. 



Our tread along the pathways which bac- 

 teriology opened has become firmer as the 



