ACUTE BRONCHIAL CATARRH. 63 



Secondly. If the current of the blood in the great branches of the 

 aorta encounter an obstacle, and more especially if the aortic stream 

 itself be impeded below the point of origin of the bronchial arteries, the 

 pressure of the blood is augmented in the other arteries which are not 

 compressed or otherwise constricted, and hyper^emia ensues throughout 

 the range of their capillary system. As an instance of this process 

 (which Virchow aptly terms " collateral fluxion ") we find sometimes 

 that, in consequence of compression of the abdominal aorta by liquid in 

 the peritonaeum, or by accumulations of excrement or gas in the intes- 

 tines, augmented pressure from within takes place in the bronchial and 

 carotid arteries, resulting in " congestion of the brain or lungs." So in 

 the cold stage of intermitting fever the circulation encounters a mate- 

 rial obstruction (throughout the periphery of the body), from the cutia 

 anserina, and the spasmodic contraction of the peripheral arteries. Per- 

 haps this is the reason of thehypersemia and catarrh of the bronchial mu- 

 cous membrane, which often complicate intermitting fever, and of the 

 cough which, in certain patients, is very distressing during the attack. 



Thirdly. Irritants which act directly upon the mucous membrane, 

 such as dust, vapors, too cold or too hot air, occasion in it hyperasmia 

 and catarrh. Those who follow certain trades, as bakers, millers, and, 

 above all, stone-cutters, suffer constantly from this disorder. 



Fourthly stands chilling of the external skin, and the action upon 

 it of a sudden change of temperature. As we have observed, we can- 

 not satisfactorily account for the phenomenon, almost daily observed, 

 of a person suffering from bronchial catarrh after seating himself in a 

 draught of air while perspiring freely. The process cannot be ascribed 

 to collateral fluxion, since a mere change of temperature or exposure to a 

 current of air, or to a degree of cold by no means severe, suffices to bring 

 on the attack. In bleak, damp localities, particularly on the sea-side, 

 such exciting causes are so numerous that bronchial catarrh is endemic. 



Fifthly. It forms a symptom of typhoid fever, measles, and small- 

 pox. Here it must be looked upon as the result of a morbid state of 

 the blood, which has absorbed some deleterious material, with the nature 

 cf which we are unacquainted. However, although we cannot explain 

 what we see upon physiological principles, there is something analogous 

 to it in the symptoms of poisoning, which we can produce at will by 

 the exhibition of an inorganic material (iodide of potassium) in large 

 doses. As is well known, a very violent bronchial catarrh, often 

 accompanied by an exanthema of the skin, not unfrequently arises 

 during the employment of this agent, no other irritant having come 

 into operation meantime either upon skin or mucous membrane. 



Sixthly. Under the operation of unknown atmospheric or telluric 

 influences, from time to time, epidemics arise, in which very extensive 

 catarrh occurs, with unusually severe constitutional disturbance. It is 



