5 6 BA CTERIOLOG Y. 



possible bundle of light-rays. The spores, moreover, 

 take up staining-reagents much less readily than do 

 the micrococci. The most reliable differential points, 

 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. 



A convenient classification of bacilli is that based 

 upon constant characteristics which are seen to ap- 

 pear in the course of their development under spe- 

 cial conditions certain of them possessing the power 

 of forming spores, while from others this peculiarity 

 is absent. 



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 comparatively limited number of cases. Mor- 

 phologically, 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 



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 



i Dividing into two transversely. 



