PREFACE TO SIXTH EDITION 



More than the usual amount of time and effort has been given toward 

 making this new edition of Bergey's Manual useful. The volume has 

 been completely revised and is reset in double column format so that each 

 page carries about 20 per cent more type than the pages in the fifth edition. 

 Those who are interested in special groups of bacteria will find something 

 new in the presentation of the relationships in every genus. Because 

 of our rapidly expanding knowledge, changes in the outline classification 

 and text were made necessary. These changes have in every case been 

 made by speciahsts in consultation with the Editorial Board. Every spe- 

 cialist possesses first hand knowledge of the species in the group that he or 

 she has reviewed. 



Because increasing knowledge has shown the fission fungi to be a larger 

 and more diversified group than previously realized, the number of species 

 described has increased from 1335 in the fifth edition to 1630 in the present 

 edition of the Manual. This number does not cover all of the descriptions 

 found in the literature for, as in all other fields of biology, many of the 

 descriptions are so inadequate that the species described cannot now be 

 identified. Many descriptions are obvious or probable duplications of 

 previous descriptions while still others are based on nothing more substan- 

 tial than the author's belief that he had something new, he having made 

 but little effort to compare his cultures with those found by previous 

 investigators. An indication of the large number of inadequate descrip- 

 tions will be found by referring to the material in the appendixes to the 

 various groups, and to the index where synonyms and incompletely 

 described species are shown in italics. 



The large number of these poorly described species suggests that there 

 has been much unsatisfactory work done in the field of bacteriological 

 taxonomy. Progress in this inadequately developed field is needed as it 

 would help to clarify the approach to desirable research in many fields of 

 bacteriology. 



It is believed that both teachers and investigators will find the new 

 Source and Habitat index useful. It is important to know what organisms 

 have been described from any given habitat in determining the identity of 

 a described species or whether a given species is new. 



The future development of taxonomic work holds several interesting 

 possibilities of increased international cooperation such as between the 

 various National Type Culture Collections and within the International 



