THE RESPIRATORY SYSTEM 143 
cause is frequently found to be tuberculosis or mycosis. 
Inflammation of the larger passages is nearly always 
accompanied by pulmonary congestion, a serious con- 
dition in birds as will be seen later. A few of these cases 
have been studied bacteriologically with no definite result, 
nor have these cases occurred in such groups that an 
epizootic was suggested. Bact. avisepticum, Bact. cani- 
septicum, Bact. coli, Bact. aerogenes mucosum, and Ps. 
pyocyaneus, Streptococcus hemolyticus and non-hemo- 
lyticus and staphylococci have been found. 
A review of the active verminous lesions of the bronchi 
and the pneumonitis to wliich parasites lead, shows again 
the highest number among the Camivora, with negligible 
percentages among the Aves. The forms concerned are, 
when determined, ascarides, strongylus, hepaticola, fas- 
ciolopsis, cytoleichus, pneumonyssus and paragonimus; 
these will be discussed later. The lesions in the bronchi 
are mucocatarrhal or hypertrophic; occasionally actual 
ulcerations are seen. What is more important however is 
the peribronchitis leading to interstitial pneumonitis and 
to bronchiectasis' of the smaller bronchi, or to areas of 
atelectasis by total occlusion of some small air passage. 
This pathology is fairly well recognized among veterinary 
pathologists but there are two points which seem worthy 
of special emphasis, namely, the relative mildness of the 
changes in the larger bronchi and the importance of the 
worms as causes of pneumonia. In regard to the first 
it can be pointed out that the trachea and its branches 
need not be altered at all while the middle sized bronchi 
present a mottling of small recent congestion with pig- 
mentations from old hemorrhages, together with slight 
unevennesses of the surface. Small bronchi on the other 
hand are the seat of ulcerative internal processes and 
quite marked peribronchitis, as indicated by round and 
connected tissue nuclei or perhaps polynuclear increase 
under active acute inflammation; it is in the latter case 
that acute pneumonitis is present. 
