62 BACTERIOLOGY. 



In some the threads appear rigid, in others flexible. 

 They are motile and multiply apparently by the simple 

 process of fission. 1 In most respects, save form and the 

 property of producing spores, they are analogous in 

 their mode of growth to the bacilli. 



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 inden- 

 tation will increase in extent until there exist eventually 

 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 

 juxtaposition are flattened against one another, and not 

 infrequently 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 groups of fours as tetrads. 



In the formation of staphylococci such division occurs 

 irregularly in all directions, resulting in the production 

 of the clusters in which these organisms are commonly 

 seen. (See Fig. 2, a.) With the streptococci, however, 

 the tendency is for the segmentation to continue in one 

 direction only, resulting in the production of long chains 

 of 4, 8, and 12 individuals. (See Fig. 2, b.) 



The sarchiEe divide more or less regularly in three 

 directions of space ; but instead of becoming separated 

 the one from the other as single cells, the tendency is 

 for the segmentation to be incomplete, the cells remain- 

 ing together in masses. The indentations upon these 

 masses or cubes, which indicate the point of incomplete 



1 Dividing into two transversely. 



