viii Preface. 



the expression, is greatly influenced by works of the latter kind, 

 and the chief reason for this, if I am not mistaken, lies in the 

 absence of a general view of the subject itself and of its relations 

 to other portions of natural history; we cannot see the wood for 

 the trees. An attempt to give such a view would be no mere 

 superfluous addition to existing works, and this consideration 

 was a decisive reason in the judgment of myself and of those 

 who gave me their encouragement for afterwards transcribing 

 and publishing my lectures. 



The present treatise, therefore, must not be expected to be 

 a Bacteriology, or even to report and enumerate all the details 

 which may be of interest and importance ; it should rather 

 serve only as a guide for the direction of the student through 

 these details. 



Many readers, devoted to the study of the Bacteria, will be 

 familiar with the literature or with the guides to it before they 

 take up this book. For the sake of those who seek to gain 

 some knowledge of the subject from its perusal, and also for 

 the purpose of naming the most important sources of informa- 

 tion which I have made use of along with my own investigations. 

 I have added a few notices of publications at the end of the 

 volume, and have indicated by numerals in brackets the places 

 in the text to which the citation marked with the same number 

 refers. 



So much by way of introduction to this little work. I trust 

 that it may do something to clear up existing views on the 

 subject of the Bacteria, and to lead the investigation of these 

 organisms from its present stage of storm and pressure into the 

 ways of quiet fruitful labour and increase of knowledge. 



The above with the omission of one sentence is the word- 

 ing of the preface written in July, 1885, for the first edition of 

 this book. The kindly reception which it met with can only 



