INTRODUCTION 



The science of biology has for its object the study of organic beings, 

 and for its end the knowledge of the laws of their growth, 

 organisation, and function. From the earliest times of man that life 

 has been studied and the observations recorded. Thus there has come 

 slowly to be a considerable accumulation of knowledge concerning the 

 various forms (morphology) and functions (physiology) of organised 

 life. In the midst of this gradual accumulation of facts we begin to 

 see incoherence becoming coherent, chaos becoming cosmos, and 

 apparent chance and accident becoming law. 



Bacteriology is a pq,rt, a chapter, of general biology, and is 

 concerned with the facts, as at present known, of some of the lowest 

 forms of micro-organic Hf e. Owing to a variety of circumstances, the 

 chief of which is the relation of these micro-organisms to disease, the 

 study of bacteria has assumed a place among the branches of biology 

 of somewhat exceptional importance. The application of biology to 

 daily life and its problems has in recent years been nowhere more 

 marked than lq the realm of bacteriology, where the great names of 

 Pasteur, Koch, and Lister, represent the modern epochs of advance. 

 Turn where we will, we shall find the work of the unseen hosts of 

 bacteria daily claiming more and more attention from practical people, 

 and thus biology, even when concerned with the work of microscopic 

 cells, is coming to occupy a new place in the minds of men. Its 

 evolution begins to form part of the general social evolution. 



Certainly the recent development of bacteriology forms a remark- 

 able feature in the scientific advance of our time. Not only in the 

 diagnosis and treatment of disease, nor even in the various applications 

 of preventive medicine, but in every increasing degree and sphere 

 micro-organisms are recognised as agents of good or iU no longer to 

 be ignored. They occur in our drinking water, in our milk supply, in 

 the air we breathe. They ripen cream, and flavour butter. They 

 purify sewage, and remove waste organic products from the land. 

 ' They are the active agents in a dozen industrial fermentations. They 

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