MODE OF MULTIPLICATION 67 



however, are the infallible properties possessed by the 

 spores of developing into bacilli, and by the spherical 

 organism with which they may have been confounded of 

 always producing other micrococci of the same spherical 

 form. 



We have less knowledge of the life-history of the spiral 

 forms. Efforts toward their cultivation under artificial 

 conditions have thus far been successful in only a compara- 

 tively limited number of cases. Morphologically, they are 

 thread- or rod-like bodies which are twisted into the form 

 of spirals. In some of them the turns of the spiral are long, 

 in others quite short. In some the threads appear rigid, in 

 others flexible. They are motile and multiply apparently by 

 the simple process of fission. 1 



Mode of Multiplication. The micrococci multiply by 

 simple fission. When development is in progress a single 

 cell will be seen to elongate slightly in one of its diameters. 

 Over the centre of the long axis thus formed will appear a 

 slight indentation in the outer envelope of the cell; this 

 indentation will increase in extent until there exist even- 

 tually two individuals which are distinctly spherical, as was 

 the parent from which they sprang, or they will remain 

 together for a time as diplococci; the surfaces now in juxta- 

 position are flattened against one another, and not infre- 

 quently a fine, pale dividing-line may be seen between the 

 two cells. (See Fig. 2, c and d.) A similar division in the 

 other direction will now result in the formation of fours as 

 tetrads. 



In the formation of staphylococci such division occur 

 irregularly in all directions, resulting in the production of 



1 Dividing into two transversely. 



