154 DISEASE IN WILD MAMMALS AND[BIRDS 
T\dtliin the secondary alveoli but the primaries also 
contained it. The microscopic section may not have rep- 
resented the process at all places, and since the arrange- 
ment of fibrin is similar in definitely catarrhal lesions, 
these may of course have been instances of pseudo- 
lobar pneumonia. 
Our data are too few to draw any conclusions as to the 
behavior of the various orders but one note may be per- 
mitted. The passerine birds have a great tendency to 
dense cellular infiltrates while parrots show more coagu- 
lative or fluid exudates. 
Pkoduction of Insular Pneumonia in Birds. 
Insular consolidations in which catarrhal and infiltra- 
tive processes are prominent, the bronchopneumonias, 
seem to arise in two ways. One course of events appar- 
ently follows infection via the broncliial mucosa, the other 
via the blood stream and a study of the resulting lesions 
may help toward an understanding of the development of 
pneumonia in man. 
When infection unquestionably has been superficial, 
that is via the bronchus, the first thing to happen is a 
swelling of the septal prolongations dividing the primary 
alveoli and an extension of their ends farther into the 
secondary alveoli with the result that the inlet to the 
primary air sacs is narrowed and the space in the second- 
aries is reduced. Upon the surfaces there then develops 
the usual catarrhal exudate while in the deeper parts 
marked congestion makes its appearance. Fibrin may 
develop and be mixed with the cells both in the larger and 
smaller alveoli but it is more evident in the former. 
(Figs. 8, 9, 10.) 
The other process by which insular pneumonia de- 
velops seems to begin in the septa of the smaller alveoli 
and in the perivascular areas. This has been looked upon 
as hematogenic or pleurogenic. The first change occurs in 
the surroundings of the primary alveoli where there 
