PREFACE 



In L922, Professor I). II. Bergey of the University of Pennsylvania wrote to 

 me thai he and the Committee on Characterization and Classification of the 

 Society of American Bacteriologists were in the process of preparing a "Manual 

 of Determinative Bacteriology"; he asked whether I would be willing to under- 

 take the preparation for thai volume of a section dealing with the actinomycetes. 



This group of organisms had occupied my attention for the previous several 

 years, and alone ( L919) and with Roland Curtis ( 1916), 1 had described a num- 

 ber of new species; yet I hesitated to accept this assignment. There were several 

 important reasons for this hesitation: (a) I was not at all sure that the descrip- 

 tions of actinomycetes so tar published provided sufficient information for the 

 accurate identification of most of the species recorded in the literature; (Id only 

 four years previously, I had been warned by the dean of American cryptogamic 

 botanists, Roland Thaxter, not to make further descripl ions of new species based 

 solely or largely upon cultural and biochemical properties; and finally (c) I was 

 not (wen certain at that time whether the actinomycetes should he included 

 with the bacteria. 



I told Professor Bergey all this and suggested thai it would he better to wail 

 a few years until more detailed information was obtained concerning this group 

 of microorganisms, especially with regard to their morphological and biochemical 

 properties, before an attempt was made to codify them. I received a curt and 

 somewhal sarcastic reply that if I would not, for one reason or another, under- 

 take this task, he would have to do it himself. My immediate answer was, "] 

 will do it." The besl that I could accomplish a1 that time was to use cultural and 

 biochemical characterist ics as a major basis for the classification of the actinomy- 

 cetes and for the characterization of the known species. 



Since then, or for more than a third of a century and for seven consecutive edi- 

 tions of "Bergey's .Manual." I have been largely responsible for the preparation 

 of the descriptions of the actinomycetes. 1 have not, however, always had the 

 final word in organization of the material for all the various editions. Alone 

 i I! 1 10), and together with Professor A. T. Ilenrici of the University of Minnesota 



(194:)), I proposed two systems for classificati f the act Lnomycetes, the second 



of w Inch consisted of a thorough revision of the group and its separal ion into four 

 genera. The most significant change in this revision was the proposal, in L943, of 

 the new generic name. Streptomyces. This second system has been the basis for 

 the organization of the material in the lasl two editions of Bergey's Manual. 



In presenting this volume, I am now certain of one thing, namely, that the 



place of the actinomycetes is definitely a ug the bacteria and not among the 



fungi. Ample evidence of this belief has been presented in Volume I of this trea- 

 tise. Unfortunately, the firsl reason for my hesitancy in L922, I believe, remains 

 valid; the accuracy of the information available for species identification i> ,-iill 



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