76 BACTERIOLOGY. 



bacillus of influenza, but ovoid in shape. It is found 

 constantly in the sputum of early cases of whooping- 

 cough. It can be cultivated on the usual culture media 

 if blood or its coloring matter is present. 



The infection localizes itself in the throat, nose, 

 and bronchial tubes, and is spread by the secretions 

 from these parts. It is transmitted from one child 

 to another, chiefly by direct contact, less often through 

 dwellings and schools that have been infected. 



One attack generally protects during life; so 

 cases of reinfection are very rare. The toxins of the 

 bacillus are within the bodies of the bacterial cells 

 (endotoxins). Efforts have been made to immunize 

 against the disease and to modify its course by inject- 

 ing the killed bacteria. The results have been fairly 

 successful. 



THE KOCH-WEEKS BACILLUS. 



This organism is the cause of acute infectious 

 conjunctivitis, commonly called "pink eye." It re- 

 sembles closely the bacillus of influenza, but differs 

 from it in growing on. media that does not contain 

 hemoglobin. 



THE DUCREY BACILLUS. 



This bacillus is of very small size, and has a 

 tendency to form chains. It is not motile and does 

 not form spores. . It stains with all the ordinary dyes, 

 but more deeply at the ends. It will grow only on 

 media containing human blood. 



