18 BIOLOGY AND TECHNIQUE 



forms of which are rather easily injured by heat, light, drying, and 

 chemicals have a comparatively enormous resistance 1o 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 minutes, anthrax spores are able to resist the same disinfect- 

 ant 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 

 minutes and more. 



Whenever the spores of any microorganism are brought into an 



a, O &O *W C^* C?* 



FIG. 5. GERMINATION OF SPORES. 



environment suitable for bacterial growth as to temperature, mois- 

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

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

 elongation of the spore body with a loss of its highly refractile char- 

 acter and resistance to staining fluids. The developing vegetative 

 cell may now rupture and slip out of the spore membrane at one oi 

 its poles, leaving the empty spore capsule still visible and attached 

 to the bacillary body. Again, a similar process may take place equa- 

 torially instead of at the pole. In other species again, there may 

 be no rupture of the spore membrane at all, the vegetative form aris- 

 ing by gradual elongation of the spore and an absorption or solution 

 of the membrane which is indicated by change in staining reaction, 

 Division by fission in the ordinary way then ensues. 



