CHAPTER IV 



The Bacterial Nucleus 



A: HISTORICAL 



(i, 3, 5, 10, 14, 15, t6, 17, 12, 24, 2S, 42, 43, 44, 45. 50, sr, 5^, 57, 5>^, 59) 



THE existence ot the bacterial nucleus has long been denied, mainly 

 upon the evidence that it cannot readily be demonstrated in prepara- 

 tions fixed and stained according to standard bacteriological procedures 

 (Chapter II). Good descriptions of the nuclear apparatus, as it is now believed 

 to exist, have been published from time to time, but have been ignored by 

 almost all bacteriologists. 



It is significant that the observations upon eubacteria, made in the last 

 decade, were preceded by an interest, in widely separated parts ot the globe, 

 in the cytology of myxobactcria. These micro-organisms cannot readily be 

 studied in heat-fixed smears, and so received the cytological treatment usually 

 denied to eubacteria. Also their nuclear material can clearly be demonstrated 

 by simple staining techniques, which that of eubacteria often cannot. The 

 application, to other fields of bacteriology, of the information obtained from 

 the study of myxobactcria, gave considerable stimulus to those minds which 

 had difficulty in accepting the defeatist views upon bacterial cytology, which 

 had been current for so long. 



A revolution in the study of the bacterial nucleus resulted from the adoption 

 of the technique of acid hydrolysis, as a preliminary to staining. This was 

 originally applied in the process o{ the Feulgen reaction for nucleic acid, 

 which was used successfully by Stille and by Piekarski in 1937, and by many 

 others at about the same time. Piekarski also discovered that after acid 

 hydrolysis the nuclear structures stained clearly with Giemsa. This technique 

 was adopted by Robinow (1942), whose beautiful photomicrographs attracted 



