THE BACTERIAL NUCLEUS 7I 



In the case of Streptococcus Jaccalis, which is a short-chained streptococcus, 

 resembUng a smooth bacterium in the possession of two pairs of nuclear units 

 and in its mode of division, by constriction of the cell wall (Chapter III), 

 the fusion nucleus is rod-shaped, with its axis longitudinally disposed in the 

 oval coccus. The rod is transformed into a single, central mass, from which 

 small fragments break off, as in the case of the lactobacillus. The filament 

 which is produced is comparatively short, and gives rise to three instead of 



A B 



(Reproduced frotn the Journal of Hygiene.) 



Fig. 32 



TRACINGS OF PHOTOMICROGRAPHS OF VEGETATIVE FUSION CELLS 



A. Shigella flexneri. 



B. Bad. coli. 



Showing three pairs of chromosome complexes. 



six cells upon fragmentation. The occurrence, in both cases, of a multiple 

 of three, which is the number of pairs of chromosomes in the smooth type 

 of fusion cell, indicates a similarity of constitution of the streptococcal fusion 

 cell. 



Filamentous cells, containing chromosome fusions of this type, occur also 

 in myxobacteria and in chlamydobacteria, but the details of the process, as 

 it occurs in these bacterial orders have not been described. 



It has been noted that this process does not appear to occur in spore- 

 bearing bacilli. In these organisms, however, there is evidence of a complex 

 method of vegetative reproduction which entails the liberation of small bodies 

 which grow up into bacilli (Chapter VII). 



In addition to vegetative cells which resemble those of other. Gram- 

 negative bacteria, cultures of Proteus contain swarmer filaments of considerable 

 length, containing a large number of nuclear units. These filaments appear 

 ' to be unicellular, but their nuclear material is arranged in a simple, repetitive 



