Preface 



The main purpose of this Atlas is to present a unified exposition 

 showing the shape and arrangement of the flagella on representative 

 strains of all available species of bacteria. The illustrations are all 

 in the form of photomicrographs of stained preparations personally 

 prepared by the author. In addition to the normal shapes and 

 arrangements, the observed variations and mutations of flagellar 

 shapes and arrangements are illustrated. Measurements of flagellar 

 wavelengths and amplitudes were made on all cultures studied and 

 these are recorded in the Atlas. With each genus is included the 

 source of the cultures studied and a discussion of their authenticity 

 and identity. 



To enhance the practical value of the Atlas for bacteriologists, 

 several chapters are included dealing with the various factors which 

 influence bacterial motility and flagellation, technical details on the 

 staining of flagella, and various methods by which flagellar varia- 

 tions and mutations may be studied. 



Flagella are undoubtedly the locomotor organs of bacteria. Their 

 composition is much the same as that of contractile tissue in general, 

 such as muscle tissue. They are extremely thin, averaging only 20-30 

 millimicrons in diameter. The helical shape is most characteristic 

 and most efficient for locomotion. The flagella originate from be- 

 neath the cell wall and perhaps from definite structures or kineto- 

 plasts. How they operate to move the bacteria is not known, nor 

 is the nature of the activating stimuli understood. Being locomotor 

 organs, the shape of the flagella and their arrangement on the 

 soma are determined by the genetic constitution of the bacteria. 



Flagellation is a major basis for bacterial identification and 

 classification. Because of technical difficulties experienced by many 

 bacteriologists, the nature of the flagellation has been omitted from 

 the original descriptions of many bacterial species. In some in- 

 stances the flagellation has been incorrectly described. The Atlas 

 should do much to rectify this situation and place morphology in 

 its proper and preeminent place in bacterial taxonomy. 



