BACTERIA 11 



property, namely, great resistance to harmful influences such as 

 heat, chemicals, etc. 



The spore may be formed in any part of the bacterium but its 

 position is generally constant in the same species. It may lie 

 within the center of the cell without changing the contour of the 

 latter, or it may distend the central part of the cell, giving it a 

 spindle-like shape, or it may be formed at one end, giving the 

 bacterium the appearance of a drumstick. 



When conditions again become favorable for growth, the or- 

 ganism assumes its original form. The spore absorbs moisture, 

 becomes swollen, and loses its slimy refractile appearance ; later a 

 little bulging is seen on one side of the cell if the spore is central 

 or at the extremity if the spore is polar. This protrusion continues 

 until finally the spore envelope bursts and a rod of soft protoplasm 



(i) 



FIG. 4. (a) Position of Spores. (6) Germination of Spores. 



emerges which then commences to function in the ordinary manner 

 of its species (Fig. 4). 



Spore formation must not be regarded as a method of reproduc- 

 tion ; it is a resting stage which should be contrasted with the 

 vegetative stage when active multiplication takes place. It occurs 

 most frequently in bacilli, less often in spirilla and very rarely 

 in cocci. Fortunately there are very few spore-bearing organisms 

 pathogenic for man, a fact which greatly simplifies disinfection 

 and the treatment of infectious diseases. 



Two views are advanced regarding the significance of spore 

 formation in bacteria. According to one view it is considered as 

 a period of rejuvenescence and that an alternation between the 

 vegetative and spore stage is necessary in order that the species 

 may maintain its highest vitality. In support of this view there 

 exists the fact that in some cases sporulation will cease at a temper- 

 ature above or below the optimum, while vegetative growth will 

 have a much longer range. The anthrax bacillus if kept at a 



