124 MANUAL OF BACTERIOLOGY. 



cultivated at a temperature as high as 42° C. for a sufficiently 

 long time, the anthrax bacillus becomes incapable of forming 

 spores; but as long as it retains any virulence at all it remains 

 capable of forming spores.* Spores themselves do not mul- 

 tiply, nor do they manifest any activity. They may be located 

 at the center of the bacillus or nearly at one end; in the latter 

 case the end of the bacillus is likely to enlarge, making a form 

 having the shape of a drumstick ; this is seen in tetanus bacilli 

 (Fig. 44). When a bacillus assumes a spindle shape on ac- 

 count of having the middle part bulged through the formation 

 of a spore it is called a Clostridium. With rare exceptions, a 

 single bacillus contains but one spore. Under favorable con- 



FiG. 47. — Bacteria showing flagella. 



ditions the spores germinate, as it is called, and develop to the 

 adult form of the organism. This may be witnessed in hang- 

 ing-drop preparations. 



Spore formation is not a method of multiplication, since 

 one spore when it germinates reproduces but one cell, and 

 this cell then multiplies. So spore formation seems to be a 

 means of preserving the organism under unfavorable environ- 

 ments, and is not a process of reproduction in a strict sense. 



Motility.— Motility is rarely exhibited by micrococci; some 

 bacilli possess it and some do not; while nearly all of the 

 spirilla are motile. The phenomenon is observed in the hang- 

 ing-drop. The degree of motility is variable, being sometimes 

 slight and sometimes very active. When seen under a high 

 power the little particles taken from a culture of a motile 



*KoUe and Wassermann. loc. cit. p. 42. 



