70 THE CYTOLOGY AND LIFE-HISTORY OF BACTERIA 



This method of reproduction, as it occurs in rough bacteria and also in 

 streptococci, is essentially similar to that in smooth bacteria but differs sHghtly 

 in detail. The fusion cell of a lactobacillus is approximately the same size 

 as the four-celled rough bacterium, and contains two, large, nuclear bodies. 



(Reproduced from the Journal of Hygiene.) 



Fig. 31 



THE PRIMARY NUCLEUS AND VEGETATIVE FUSION CELLS 

 IN VARIOUS BACTERIA 



((a) Primary nucleus ; (b) Fusion cell, in each case) 

 Top left — Smooth bacterium. 

 Top right — Rough bacterium. 

 Bottom left — Myxobacterium. 

 Bottom right — Short-chained streptococcus. 



The individual chromosomes cannot be resolved in this case. The filament 

 increases in length and eventually fragments, exactly as in the case of the 

 smooth types, but the behaviour o£ the nuclear material is slightly different. 

 The central mass of chromatin retains its identity for some time after the 

 commencement of growth. Small fragments break of^ and migrate along 

 the filament, and eventually the chromosome pairs arc evenly distributed 

 along its length. The filament then fragments into bacillary forms ; how 

 manv has not been determined. 



