DIPLOCOCCUS PNEUMONIA 361 



tures in the bronchi and blowing them into the finer bronchioles with 

 air. Similar experiments have been made by Winternitz and Hirsch- 

 felder. 1 



In man, the most frequent lesion produced by the pneumococcus is 

 acute lobar pneumonia. About ninety per cent of all cases of this 

 disease are caused by the pneumococcus, 2 the remainder being due to 

 streptococci, influenza bacilli, Friedlander's bacilli, and exceptionally 

 to other microorganisms. Lobular pneumonia is caused by the pneu- 

 mococcus with almost equal regularity. Infection in pneumonia prob- 

 ably occurs through the lung, and in such experiences as those of the 

 French and Americans at Panama and those of the English in the South 

 African diamond mines, it would appear that pneumonia might be a 

 contagious disease. According to Cole, 3 when pneumonia is secondary 

 to septicemia it is usually of the lobular type. Experiments of Meltzer 

 seem to indicate that infection is facilitated by closure of the small 

 bronchioles, and cold or chilling may possibly stimulate the mucous 

 glands so as to plug these. 



In the discussions given below concerning the types of pneumococci, 

 it will appear that the type of pneumococcus found in the lung not often 

 coincides with that found in the mouths of normal individuals. The 

 types I, II and III, according to Dochez and Avery, 4 are found only in 

 association with the disease, but the fourth group is the one which is 

 found in sputum of many normal individuals. A person in contact 

 with a pneumococcus patient may possibly carry the more virulent 

 groups in his mouth, thus constituting a pneumococcus carrier. During 

 the course of these diseases the cocci are found in large numbers within 

 the pulmonary alveoli, and in the capillaries and lymph vessels of the 

 lung. Whether or not the pneumococci enter the blood stream in all 

 these cases is a question not yet definitely settled. Frankel 5 states it as 

 his belief that in most, if not in all, cases, the diplococci at some time 

 during the diseases could be found in the circulating blood. Prochaska 

 in a study of ten unselected cases obtained positive blood cultures in 

 every one of them. A review of the literature upon the question indi- 

 cates positive blood-culture findings in certainly over twenty-five per 

 cent of the cases. 



1 Winternitz and Hirschfelder, Jour. Exp. Med., xvii, 1913. 



2 Netter, Compt. rend, de la soc. de biol., 1890. 



3 Cole, Harvey Lecture, New York, Dec. 13, 1913. 



4 Dochez and Avery, Jour. Exper. Med., xxi, 1915. 

 6 Frankel, "v. Leyden Festschr.," 1902. 



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