Catarrhal Bronchitis. 203 



food materials during rapid breathing, in the deep inspiration 

 following a cough, in paralysis of larynx or pharynx, in forcible 

 drenching, and above all in giving liquids through the nose. 

 Gamaleia found that an irritant tracheal injection, followed in 

 an hour by staphyococci and streptococci caused intense bron. 

 chitis in twenty-four hours. 



The glands of the bronchial mucosa must also be reckoned with. 

 These are much more abundant in the capillary bronchia than in the 

 larger tubes. Their secretions are carried outward by the cilia 

 and with them invading microbes tend to be washed out. But 

 if these microbes have once gained access to the interior of the 

 gland-ducts, through the suspension of the secretion or by 

 reason of their own growth and increase, in the contained cul- 

 ture-fluid or in the epithelial lining, they have thereby secured 

 a position of vantage from which they are less likely to be dis- 

 lodged by ciliary action or by copious secretion. From these re- 

 cesses accordingly they extend into the substance of the mucosa, 

 extending the inflammation in both breadth and depth. 



A similar advantage attends the microbes in case of abrasions 

 or minute ulcers resulting from caustic or otherwise irritating 

 gases or solids inhaled. The cilia having been removed and the 

 phagocytic power of the tissue cells suspended or impaired, the 

 injurious micro-organisms can work unimpeded. 



Bronchiectasis and other old-standing injuries act in a similar 

 way robbing the mucosa of its defensive powers. 



But this recognition of a causative microbian invasion must 

 not lead us to close our eyes to many important predisposing 

 and accessory factors without which in the great majority of 

 cases the micro-organisms would remain harmless. 



A northern or southern temperate zone, with cold, wet seasons, 

 and all localities in which cold and damp coincide, are especially 

 productive of bronchitis. High altitudes which are habitually 

 cloudy (fogs) are similarly objectionable, but, in the absence of 

 fogs, the clear, dry mountain air is beneficial. Damp air and 

 cold wind is a fatal combination, and a low dewpoint is the main 

 condition favoring bronchitis. I^ate autumn and early spring 

 with their sudden and extreme changes of temperature and air 

 moisture are the great periods of acute bronchitis, while the 

 cold, dry zero air of midwinter, in our northern states, in the 

 centre of the continent is comparatively little injurious. 



