TYPES OF PNEUMONIA. 205 



which both an acute croupous condition and an acute 

 catarrh occur in the same lung. 



Besides these two clinical types of pneumonia there 

 is another group of cases which are somewhat loosely 

 denominated septic pneumonias, and which may arise in 

 two ways : (i) by the entrance into the trachea and bronchi 

 of discharges, blood, etc., which form a nidus for the 

 growth of septic organisms, and thus infect the tissue of the 

 lung; (2) from secondary pyogenic infection by means of 

 the blood stream from suppurative foci in other parts of the 

 body. (See Chapter on Suppuration, etc.) 



We shall see that bacteria have been found associated 

 with all these types of pneumonia. Special importance is 

 attached to acute croupous pneumonia on account of its 

 course and characters, but reference will also be made to 

 the other forms. 



Historical. Acute lobar pneumonia for long, both popularly and 

 medically, had been supposed to be an effect of exposure to cold ; but 

 there were not wanting those who were dissatisfied with this view of 

 its etiology. Not only did many cases occur where no such exposure 

 could be traced, but it had been observed that the disease sometimes 

 occurred epidemically, and was occasionally contracted by hospital 

 patients lying in beds adjacent to those occupied by pneumonia cases. 

 Further, the sudden onset and definite course of the disease conformed 

 to the type of an acute infective fever. It was thus suspected by some 

 that it might in reality be due to a specific infection. The first con- 

 tributor to the modern view of its etiology was Friedlander, whose 

 results (published in 1882-83) were briefly as follows. In the 

 bronchial contents and in sections of pneumonic lungs, there were 

 cocci, adherent usually in pairs, and possessed of a definitely con- 

 toured capsule which was faintly but distinctly stained. These cocci 

 could be isolated and grown on gelatine, and on inoculation in mice 

 they produced definite pathogenic effects. Instead of developing 

 pneumonia, however, the animals died of a kind of septicaemia with 

 inflammation of the serous membranes. The blood and the exudation 

 in serous cavities contained numerous capsulated diplococci. Though 

 of course this was not proof that the cocci were the cause of the disease 

 in man, Friedlander brought forward the growing tendency to regard 

 pneumonia as an infectious disease, the alleged universal occurrence of 

 his cocci in the lungs of persons dead of the disease, and the patho- 

 genic capacities of these cocci in animals, as indications that an etio- 

 logical factor had been discovered. Various criticisms of Friedlander's 



