MORPHOLOGY, REPRODUCTION, ETC. 



17 



D o m 



FIG, 4. VARIOUS POSITIONS OF SPORES 

 IN BACTERIAL CELL. 



membrane which is very resistant. -Muhlschlegel l believes that the spore 



membrane is a double structure, and, as stated before, Nakanishi believes 



that the spore contains nuclear material. 



The position of the spore in the mother cell is of some differential 



importance in that it is usually con- 

 stant for one and the same species. 



Thus, the spores of the tetanus 



bacillus are regularly situated at 



the extreme ends of the bacillary 



bodies, while those of anthrax are 



situated at or near the middle. 



Physiologically, sporulation is probably to be regarded as a method 



of encystment for the purpose of resisting unfavorable environment, 

 ^ and it is indeed true that species 



of bacteria the vegetative forms of 

 which are rather easily injured by 

 heat, light, drying, and chemicals 

 have a comparatively enormous re- 

 sistance to these agents after the 

 formation of spores. Thus, while a 

 10-per-cent solution of carbolic acid 

 will kill the vegetative forms of 

 anthrax bacilli within twenty min- 

 utes, anthrax spores are able to resist 

 the same disinfectant for a long 

 period in a concentration of over 50 

 per cent; and while the vegetative 

 forms of the same bacillus show little 

 more resistance against moist heat 

 than other vegetative forms, the 

 spores will withstand the action of 

 live steam for as long as ten to twelve 



a I 



OOOD<2 



G 



a O 



FIG. 5. GERMINATION OF SPORES. 

 A, Bacillus subtilis, equatorial spore 

 germination; B, Bacillus anthracis, 



germination by simple transition; C, m i nu t es and more. 

 Clostrydium butyricum, polar germi- 

 nation. 



Whenever the spores of any mi- 

 croorganism are brought into an en- 

 vironment suitable for bacterial growth as to temperature, moisture, 

 and nutrition, the spores develop into vegetative forms. This process 

 differs according to species. In general it consists of an elongation of 



' Muhlschlegel, Cent. f. Bakt., II Abt., vi, 1900, p. 65. 



