160 DISEASE IN WILD MAMMALS AND BIRDS 
of piginentation, but none, except the one above, with 
resultant fibrosis. The degree of anthracosis is usually 
so slight that it has been considered important enough to 
include in the diagnosis but eighteen times and curiously 
enough seventeen of these were observed in birds. Were 
there more cases it might be profitable to plot their exhi- 
bition period but the use of this small number might lead 
to error ; the average length of exhibition of the birds was 
about a year. It is common to observ^e some black speck- 
lings of the air sacs, as if pepper were dusted on them as 
has been said before, but even this is rarely marked. It is 
most often seen in the Anseres, Psittaci and Struthiones 
but a goodly number of cases occur in the long- 
lived Passeres. 
The distribution of the pigment is essentially the same 
throughout Mammalia — peribronchial, submucous and in 
the lymph nodes at the root of the lung. In the birds it is 
first seen in the subepithelial spaces of the septa of the 
small alveoli where they project into the secondaries, 
later accumulating in the connective tissue of the main 
septa. Collections under the pleura and at the root of 
the lung are rare, the dust usually spreading out along the 
air passages into the air sacs. 
Other forms of pneumonokoniosis are unknown. 
Although animals must inspire much dust from dry feed 
and from floors it must be caught early and removed by 
snorting or by the lymphatic drainage. It seems fairly 
well accepted that dusts are dangerous to the degree that 
they contain inorganic substance and as these animals are 
not exposed to concentrated mineral or metallic dusts, no 
effects are seen. 
Infarction of Lung. 
Infarctions of the lung, while not at all common, are 
interesting because of their incidence in the Carnivora 
and in the distribution. The figures concern the mammals 
