128 The Story of the Bacteria 



common in the cultivated soil, in street dust, 

 and in the droppings of the horse and other 

 herbivorous animals. The bacilli when grow- 

 ing in the body produce an intense poison, 

 which acts especially through and upon the 

 nervous system. Thus powerful spasms of the 



muscles are produced, 

 an d when the muscles 

 of the jaw are affected, 

 they become rigid, 

 hence the common 



FIG. 14. TETANUS BACILLI 



Showing spores name lockjaw. 



The bacillus of te- 

 tanus does not grow well in contact with 

 oxygen, and when it finds itself under un- 

 favorable conditions for growth, it forms 

 a spore which is very resistent to external 

 influences, and drying, heat, disinfectants, 

 etc., which ordinarily kill bacteria. Then 

 it stands pat and waits for something bet- 

 ter to turn up. The bacteriologist, how- 

 ever, can cultivate it by shutting oxygen out 

 of his tubes and plates and consulting its 

 peculiar tastes in other ways. The bacillus 

 when forming spores is shaped something 



