INTRODUCTION 



usually employed in routine bacteriology, and the necessity for the employ- 

 ment of more refined methods of examination has encouraged the study of 

 eubacteria in a similar manner. The readily-demonstrable nuclear structures 

 and beautiful and complex life-cycle of myxobacteria stimulated the search 

 for the truth concerning the parallel structures and processes in those bacterial 

 genera more commonly encountered in the laboratory. 



The studies of biochemists upon the nucleoproteins of bacteria have also 

 contributed greatly to the increase in our knowledge of, and interest in, the 

 problems of bacterial cytology. One of the most useful staining techniques 

 tor the demonstration of the bacterial nucleus is a direct adaptation of a 

 microchemical test, the Fculgen reaction, which has itself given much 

 information upon the subject. 



Bacteria have recently come to be regarded as suitable material for genetical 

 studies, and although little has so far been done to correlate genetical and 

 cytological information, a gratifying degree of mutual support has already 

 been achieved (Chapter X), and it is to be hoped that the interchange of 

 information between these two branches of bacteriology may, in the future, 

 prove as helpful to both as it has done in other biological fields. 



The information compiled in the following chapters has been obtained 

 by classical microscopic methods, in most instances, but a considerable advance 

 m the techniques of electron and phase-contrast microscopy, as applied to 

 this subject, has in the last few years provided valuable confirmatory evidence 

 on several points, and promises to do more. It should be emphasised that a 

 reasonable degree of correlation between the results obtainable by different 

 techniques must always be sought before too much weight is placed upon 

 any one of these. The disagreements which have arisen in bacterial cytology 

 have been surprisingly few. But almost all of these have been caused by the 

 uncritical reliance of a single worker, or a small group, upon a single methoci. 



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