

THE PRINCIPLES OF 

 BACTERIOLOGY. 



CHAPTER I. 



THE STRUCTURE OF BACTERIA. 



DURING the last decade the science of bac- 

 teriology has become one of the most prominent 

 branches of the tree of knowledge. Words of 

 the craft, like " pure culture," belong as much 

 as the phrases " struggle for existence " and 

 " conservation of energy " to those scientific 

 idioms which have been admitted to citizenship 

 in the general community of speech. 



The organisms known as bacteria are mem- 

 bers of the lowest group of the plant kingdom. 

 They would in themselves arouse hardly more 

 attention than some of the algae, slime-fungi, 

 or moulds, were it not for the supervention of 

 some special interest. This special interest 

 lies in the fact that bacteria are those organ- 

 isms which research has brought into relation 

 with the questions of spontaneous generation, 

 fermentation and decay, and the origin of dis- 



