THE BACTERIAL NUCLEUS 



69 



redistributed in the filament, and the latter then fragments into nidividual 

 bacteria, each containing two pairs ot chrcMiiosomes. Thus each chromosome 

 of the original six becomes the parent of the entire complement of two pairs 

 in one daughter bacterium. The occurrence ot the fusion process has now 

 been confirmed by genetic studies (Section G, below). 



^ 



^ 



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r\ 



<j 



^ 



{Reproduced front the Journal of Hygiene.) 



Fig. 30 

 CO.MPLEX VEGETATIVE REPRODUCTION IN BACTERIUM 



The trinucleate cell precedes the fusion cell with its three pairs of chromosome complexes. 

 Within the fusion cell there is one nuclear division. The six chromosome pairs are re- 

 distributed in the growing filament. There is a second nuclear division and the filament 

 fragments into six daughter cells, each with the full complement of two pairs of chromosome 

 complexes. In streptococci only three daughter cells are formed. 



Notliing has been recorded of the process by which the fusion cell which 

 inaugurates this series of changes attains its form and nuclear complement. 

 Bacteria occur which are probably the precursors of the fusion cells, as they 

 contain three pairs of chromosomes, arranged in a more normal manner, 

 with one pair at each end and one in the centre of the bacterium. But how 

 these are derived from a bacterium with two pairs is not easy to understand. 



ana some un 



detected process of reduction may be entailed. 



