THE EP:SPIRATORY SYSTEM. 



499 



above mentioned, and other bacteria have been occasionally found.' 

 Pathogenic moulds may be excitants of acute forms of lobular pulmonary 

 inflammation. 



It will thus be seen that while it is convenient to group the exudative 

 forms of pulmonary inflammation on the basis of distinctions which are 

 in part morphological, in part etiological, the types in fact frequently 

 merge or concur. This should not lead to confusion if we remember 

 that these are infectious diseases whose most conspicuous lesion is located 

 in the lungs, and that they are not species in the natural history sense, 

 for which fixed and definite characters must be established, but that the 

 groups only indicate various forms and phases of response of a living 

 organ in various conditions of susceptibility to the damage inflicted by 

 one or another, and not infrequently by two or more combined forms of 



FIG. 280. Am VESICLE IN BRONCHO-PNEUMONIA WITH STREPTOCOCCI. 



This specimen is from a case of broncho-pneumonia complicating a pseudo-membranous inflammation 

 of the larynx in scarlatina. Exfoliated epithelium, leucocytes, and a little fibrin with the streptococci form 

 the scanty exudate. 



micro-organisms. These pneumonias are not considered among the infec- 

 tious diseases where they logically belong, partly because there are prac- 

 tical advantages in grouping pulmonary lesions together and partly be- 

 cause our knowledge of the relative frequency and significance of the 

 bacterial excitants of the various types is still in many cases too incom- 

 plete to permit the establishment of a distinctive and clearly defined 

 form of infection. 2 



1 For a study of the bacteriology of lobular pneumonia, especially in adults, see 

 Blumer, Albany Med. Annals, vol. xxii., August, 1901. 



2 For a resume of earlier attempts to induce experimental pneumonia in animals, 

 consult AufrecM in Nothnagel's "Specielle Pathologic u. Therapie," Bd. xiv., Th. 2, p. 

 36, bibliography, p. 221. 



For a study of bacteria in the lungs and their relationship to pneumonia, consult 



