X PREFACE TO THE FIRST EDITION 



or more important species, and at least approximately place the 

 others within their proper family and genus; and to furnish refer- 

 ences to general works or specific monographs where detailed infor- 

 mation on particular forms may be found. 



The book has grown out of a lecture course which has been offered 

 for some years to advanced students in that ever-growing group 

 that have planned their college work with the definite idea of be- 

 coming bacteriologists. It is therefore a sort of textbook. But it 

 will also, I hope, find a field of usefulness as a handbook to be kept 

 in the clinical or technical laboratory for reference when problems 

 involving yeasts, molds, or Actinomycetes are encountered. I feel 

 strongly that bacteriology has distinctly suffered from a too sharp 

 division of the science into categories according to particular fields 

 of application. I have therefore attempted to deal equally with the 

 medical and industrial applications of the subject. If the book seems 

 to be somewhat overbalanced on the medical side, this is due to the 

 richer literature available in that field. 



No claims are made for the work on the grounds of completeness 

 or originality. It has been my task to select, condense, and where 

 possible simplify, from the extensive available literature, such infor- 

 mation as seemed important enough to be necessary, tangible enough 

 to be useful, to the student of microbiology. The subject has been 

 plagued by a tendency of its workers to create new species on the 

 slightest provocation, to classify and reclassify, until a bewildering 

 number of synonymous names are in use. My approach to the 

 subject has been purely pragmatic. I have avoided discussion of 

 debated problems of taxonomy except where such is necessary for an 

 intelligent understanding of the literature. I have felt that to be 

 useful the book must be kept within the scope of a small handbook, 

 and must be made as simple as the subject matter will allow. I have 

 therefore omitted discussions of numerous species and genera which 

 are of no practical importance, or which are so uncommon that they 

 are not likely to be encountered in routine bacteriological work. 



The literature cited includes, for the most part, only works of a 

 general character or specific monographs in which extensive bibliog- 

 raphies may be found, save that more recent contributions not 

 found in such works have been included. I have as far as possible 

 provided original illustrations. It has been necessary, however, to 

 borrow illustrations of material that was not available to me. . . . 

 Department of Plant Pathology of this institution. Dr. H. E. 

 Michelson of the Division of Dermatology ... Dr. J. C. McKinley 

 of the Division of Neurology ... Dr. F. W. Tanner ... Dr. P. 



