PREFACE 



HAVING had occasion to study the literature bearing 

 on the subject of Spirochaetes in connection with obser- 

 vations which I made on two species of this genus, I 

 was struck with the voluminous and at the same time 

 scattered mass of papers to which reference had to 

 be made. I therefore thought it might be useful to 

 others if, instead of merely laying aside the abstracts 

 which I had made, I put them together in the form of a 

 small book. 



The Spirochaetes present a problem of considerable 

 interest. Their position in the scale of living things is 

 still undecided, and there is a tendency to place them 

 in a position between the bacteria and the protozoa. 

 My own observations would lead me to regard them as 

 much more closely allied to the former than to the latter. 



I have endeavored, in the first part of this work, to 

 compare the statements of different writers on the 

 morphology and behavior of Spirochaetes, with a view 

 to establishing, if possible, the features characteristic 

 of the genus. In the second part, I have dealt with the 

 separate species described. I have confined myself 

 to very brief descriptions of the various organisms and 

 of the methods employed for examining them, as those 

 who are interested in particular species or methods will 

 in any case refer to the original papers. Their task 

 will, I hope, be facilitated by the bibliography here 

 appended. This is by no means exhaustive, as many 

 papers are published in unattainable periodicals, and I 

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