BACTERIA. 



21 



Successive divisions take place, the new members either exist- 

 ing as separate cells or forming part of a community or group. 

 It has been computed that if division takes place every hour, 

 as it often does, one individual in twenty-four hours will have 

 17,000,000 descendants. 



Spore Formations. Two forms of spornlation, Endosporous and 

 Arthrosporous. First, a small granule develops in the protoplasm 

 of a bacterium, this increases in size, or several little granules 

 coalesce to form an elongated, highly refractive, clearly defined 

 object, rapidly attaining its real size, and this is the spore. The 

 remainder of the cell-contents has now disappeared, leaving 

 the spore in a dark, very resistant, membrane or capsule, and 

 beyond this the weak cell-wall. The cell-wall dissolves gradu- 

 ally or stretches and allows the spore to be set free. 



Each bacterium gives rise to but one spore. It may be at 

 either end or in the middle (Fig. 5). Some rods take on a pecu- 

 liar shape at the site of the spore, making the rod look like a 

 drum-stick or spindle, clostridium (Fig. 6). 



FIG. 5. 



FIG. 6. 



Clostridium. 



Spore Contents. What the real contents of spores are is not 

 known. In the mother cell at the site of the spore little gran- 

 ules have been found which stain differently from the rest of 

 the cell, arid these are supposed to be the beginnings, the sporo- 



