46 CLINICAL APPLIED ANATOMY. 



eyes, and the external auditory meatus, account for the distribu- 

 tion of the eczematous areas found in these localities. The 

 difficulty in cleansing the recesses of the ear, nose, fauces and 

 accessory air sinuses explains the long-continued infectivity of 

 discharges from these places. 



DIPHTHERIA. 



This disease is one which attacks mucous surfaces, and, being 

 due to infection from without, it infects the nose, naso-pharynx, 

 fauces, pharynx, or larynx primarily. The subsequent extension 

 of its membranous manifestations is usually determined by the 

 continuity of parts. Thus, in bad cases membrane may spread 

 through the larynx, along the trachea, bronchi, and bronchioles ; 

 the ear may be invaded through the medium of the Eustachian 

 tube, and the conjunctiva by way of the nasal duct. In excep- 

 tional cases false membrane may spread down the oesophagus 

 and even be present on the mucous coat of the stomach. The 

 lachrymal secretion and protective muscular mechanisms of the 

 eyelids no doubt largely account for the general immunity of the 

 conjunctiva, whilst the mechanism of deglutition and motor 

 activity of the stomach may be held responsible for the common 

 escape of the cesophageal and gastric mucous membranes. 



The mucous surfaces of the vulva, vagina and anus are some- 

 times, though rarely, the site of primary invasion. The same 

 parts may become involved during the progress of faucial diph- 

 theria, probably by infection conveyed by the fingers. In addition 

 to spread by continuity, the tissues of the body are invaded by the 

 toxin of diphtheria by the medium of the blood-vessels and lym- 

 phatics. The characteristic bacilli may be conveyed by lymphatics 

 to the glands, which drain the area primarily involved, or gaining 

 access to the blood-vessels, may become deposited in such 

 viscera as the spleen, liver and kidneys. As a general rule, 

 however, the bacilli remain localised at the point of infection 

 and parts contiguous to this, and it is the toxin alone which 

 circulates. The bacilli which are occasionally found in the lung 

 alveoli have passed along the respiratory passages. 



