66 THE CYTOLOGY AND LIFE-HISTORY OF BACTERIA 



formation of the resting nucleus in M. tuberculosis the nuclear material appears 

 in the form of a pair of chromosomes or chromosome complexes (Chapter 

 VI), but these are not normally evident at cell division. 



In those cocci which possess a spherical, vegetative nucleus it may be 

 seen to elongate with the cell in the course of division, but the details of the 



2rr# # • • 



(Reproduced from the Journal of Hygiene.) 



(Reproduced from the Journal of General Microbiology.) 



Figs. 27 and 28 

 THE SPHERICAL VEGETATIVE NUCLEUS 



Fig. 27 Fig. 28 



1. Coccus (not all are of this type). A unicellular coccus. The nucleus 



2. Corynebacterium. appears to elongate on division. 



Acid-Giemsa ■ .3000. (Compare Fig. 



7 (12). 



process are entirely obscure. Most cocci arc multicellular, however, and in 

 some of these, misinterpreted as single cells, entirely spurious " mitotic 

 figures " have been described (r./. Bisset, 1954). 



Upon this point as upon others the condition in Azotohactcr, which because 

 ot its larger size may more easily be studied, provides the best available 

 information. The vesicular nucleus ot Azotohactcr undergoes a process which 

 resembles a simple mitosis. The nuclear material becomes concentrated in 

 four chromosome complexes, two of which migrate into each half oi the 

 dividing cell and there divide and subdivide, reforming the chromatinic 



