WHOOPING-COUGH. 319 



ing-cough. The most frequent of these organisms is a very 

 small bacillus about the size of the influenza bacillus (Fig. 

 143). It also grows somewhat like the influenza bacillus. 



FIG. 143. 



Whooping-cough bacillus. 



The data at our disposal do not warrant any positive state- 

 ments as to the specificity of this germ. 



Infection in whooping-cough probably always occurs through 

 the respiratory tract, the sputum acting as the infecting 

 medium. One attack usually confers immunity. 



