SPECIAL CHARACTERS 29 



When bacteria are subjected to conditions unfavor- 

 able for their life they undergo various changes of 

 size and shape, none of which are very characteristic 

 except the so-called spore formation. By this is 

 meant the concentration of the vital powers and some 

 of the physical constituents of the bacterial cell within 

 a very small, homogeneous, highly light-refractive 

 body which is resistant to deleterious agencies and 

 which mav bear little or no resemblance to the parent 



FIG. 9 



Unstained spores in distended ends of bacilli. (Park.) 



organism. These spores are not to be considered as 

 evidences of reproduction, but merely as a resting or 

 resistance stage. When conditions of life suitable to 

 the normal appearance of the bacterium are resumed, 

 the spore will develop into the same kind of organism 

 as that from which it came. This spore forming is seen 

 among bacilli and spirilla, probably never among the 

 cocci. As a rule, only one spore is found in each 

 bacterial cell. These spore formations assist in identi- 

 fication. The practical importance of spores is that 



