BACTERIOLOGY OF WHOOPING-COUGH 3 







is hyperemic and usually covered with more or less mucus. According 

 to Arnheim, who has had numerous postmortems, there is a marked 

 desquamative catarrh of the larynx and trachea, with swelling of the 

 neighboring lymph glands. We know also that the posterior laryngeal 

 wall, near the vocal cords, is the point whence severe coughing may 

 be most readily produced, and this locality is supplied by the superior 

 laryngeal nerve, the one which produces cough when irritated. This 

 may be given as a reason for viewing the disease as an inflammatory 

 irritation of the laryngeal mucosa; however, the possibility of reflex 

 coughs due to irritation of the nasal mucosa, and the possibility of a 

 toxic irritation of the coughing- center in the medulla, though specula- 

 tive in character, might be considered. 



The above facts, therefore, furnish strong evidence that the disease 

 is due to some form of a zymotic agent, localized in all probability 

 in the upper respiratory passages, particularly the larynx and trachea. 

 This is important in determining the point of attack in attempting 

 to solve the problem of etiology. 



Possible nature of the virus. From what is known concerning the 

 nature of the causative virus of diseases of an infectious character, 

 we may consider three possible agents, viz. : protozoa, bacteria, and 

 enzymes. The last-mentioned agent may be dismissed by saying 

 that, in the animal world at least, there does not exist at present 

 evidence to indicate that such substances play any part whatever in 

 the primary causation of any known infectious diseases. In the plant 

 world, however, certain recently discovered facts seem to point to 

 the possibility of enzymes being the cause of certain diseases of an 

 infectious nature; and if this be true we should guard against over- 

 looking such a cause in studying animal diseases of unknown etiology. 

 Protozoa and bacteria are the common agents in the production of 

 disease, and it is among these that we naturally look for the final 

 solution of the problem. They may be microscopic or ultramicro- 

 scopic. We are familiar today with several diseases in animals which 

 are undoubtedly due to ultramicroscopic organisms. Such are foot- 

 and-mouth disease, hydrophobia, and probably hog-cholera. It has 

 been demonstrated that these can be produced in animals, and there- 

 fore abundant material is available for careful experimental work. 

 Whooping-cough, so far as we know, does not occur, and cannot be 



