82 BACTiSRIOLOGY. 



is that based upon constant characteristics which are 

 seen to appear in the course of their development under 

 special conditions — certain of them possessing the power 

 of forming spores, while from others this peculiarity is 

 absent. 



As yet but little is known of the life history of the 

 spiral forms. Efforts toward their cultivation under 

 artificial conditions have thus far been unsuccessful. 

 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. They are motile, and multiply apparently by 

 the simple process of fission.^ 



The micrococci develop by simple fission. When 

 development is in progress a single cell will be seen to 

 elongate slightly in one of its diameters. Over the 

 center 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 

 eventually two individuals which are distinctly spheri- 

 cal, as was the parent from which they sprang, or they 

 will remain together for a time as diplococci. The sur- 

 faces now in juxtaposition are flattened against one 

 another, and not infrequently a fine, pale dividing line 

 may be seen between the two cells. A similar division 

 in the other direction will now result in the formation 

 of a group of forms as tetrads. This, in short, is the 

 method of multiplication of the micrococci. 



In the formation of the staphylococci such division 

 occurs irregularly in all directions, resulting in the pro- 

 duction of the clusters in which these organs are com- 



' Dividing into two transver.sch-. 



