Preface to Second Edition 



THE second edition of this monograph inckides a considerable amount 

 o{ new information which serves, for the most part, to confirm and 

 expand the general theories of cytological structure and behaviour 

 in bacteria which I advanced six years ago. hi particular, greatly 

 improved demonstrations have been achieved of such, formerly rather 

 problematical processes as gonidial reproduction, nuclear reduction, and the 

 development of the flagella, and of such structures as the blepharoplast or the 

 startlingly complex cross-walls which sub-divide a staphylococcus internally. 



I have continued to place the main weight of my arguments upon my 

 own observations or upon information which I have been able personally to 

 confirm, but have welcomed several remarkable contributions to knowledge 

 in the form, for example, of Chapman and Hillier's electron micrographs of 

 sections o( Bacillus ccrens, which prove, contrary to my previous belief, that 

 the cross-wall is indeed a centripetal ingrowth, and the consummately skilful 

 phase contrast studies of Tomcsik which, while demonstrating the profundity 

 of my former ignorance of the nature of bacterial capsules, provide a gratifying 

 confirmation of my hypothesis, based upon entirely different evidence, of 

 the development of cell wall. 



Since the first edition was published there has also been a notable increase 

 in the amount of corroborative evidence provided by studies in genetics, 

 biochemistry and biophysics. The single, reductionally dividing chromosome 

 of the vegetative nucleus, which has been the subject of the most lucid 

 cytological demonstrations, has been entirely vindicated by the genetical 

 studies of Witkin and o( Cavalli-Sforza and Jinks, after a period in which 

 multiple, or even branched chromosomes, for the existence of which there 

 is no acceptable cytological evidence, were at various times postulated by 

 geneticists. And in a similar manner, the cytological and physico-chemical 

 evidence upon the behaviour of cell envelopes and flagella have been in 

 exceedingly close accordance, and have even begun to shed some light upon 

 the problems of antigenic structure. 



Since it is now the subject of a separate monograph [Bacteria, Livingstone), 

 the chapter upon bacterial systematics has been omitted, but the allied problem, 

 more cogent to this study, of cytological evidence of the evolutionary relation- 

 ships o£ bacteria, has been discussed at greater length. 



Because the text is intended to be a synthesis of available information, the 

 practice of relegating references to the head of each sub-section, except in 

 cases of argument or of historical interest, has been continued. There appears 

 to be a consensus o{ agreement that what may be lost in ease of tracing a 

 reference to a single point is more than gained in clarity and brevity. 



April 1955 < K. A. BISSET. 



^ 



