34 ESSAYS ON BACTERIOLOGY. 



cultures, and by repeatedly successful inoculation ex- 

 periments removed all doubt as to the fons et origo 

 mali. Tlie tetanus bacillus is a large rod, rounded at 

 the ends, sometimes growing to long threads. It is 

 motile, grows at ordinarj^ temperature, and is strictly 

 anaerobic — i. e., it does not grow in contact with the 

 oxygen of the air. It stains easily by the ordinary 

 methods. It is found in garden mould, on walls, in 

 putrefying fluids, in manure, and in places frequented 

 by horses. The association of tetanus bacilli with the 

 earth and with horses has been strongly insisted on by 

 a number of investigators. It is a striking fact that 

 the bacilli are not found distribiited through the body 

 after death, and that their number at the point of in- 

 fection is not proportional to the severity of the symp- 

 toms. This is explained by the discovery that the 

 bacilli give rise to a most virulent poison, which, freed 

 from germs, is capable of prodiicing death with all the 

 symptoms of the disease. The anaerobic quality of 

 the germ probably explains the fact that penetrating 

 wounds are especially liable to be followed by tetanus. 



As to erysipelas, authorities are agreed that the 

 same germ causes both traumatic and so-called idio- 

 pathic erysipelas. The sharp line hitherto drawn be- 

 tween these varieties of the disease should therefore 

 be removed. 



In regard to the bacilli of tuberculosis, some inter- 

 esting investigations have been made in several direc- 

 tions. 



