536 



BACTERIOLOGY. 



differ from it in their relation to oxygen, and they are 

 also without disease-producing properties. 



MORPHOLOGY. In the vegetating stage it is a slen- 

 der rod with rounded ends. It may appear as single 

 rods, or, in cultures, as long threads. It is motile, though 

 not actively so. The motility is rendered somewhat 

 more conspicuous by examining the organism upon a 



warm stage. 



FIG. 86. 



Bacillus tetani. A. Vegetative stage. B. Spore-stage, showing pin-shapes. 



At the temperature of the body it rapidly forms 

 spores. These are round, thicker than the cell, and 

 usually occupy one of its poles, giving to the rod the 

 appearance of a small pin. (Fig. 86.) When in the 

 spore-stage it is not motile. 



It is stained by the ordinary aniline stain ing-reagents. 

 It retains the color when stained by Gram's method. 



CULTURAL, PECULIARITIES. It is an obligate anae- 

 robe, and cannot be brought to development under 

 access of oxygen. It thrives in an atmosphere of 

 pure hydrogen, but not in one of carbonic acid. 



