112 DISEASES OF DOMESTICATED BIRDS 
bodies closely associated in the form of a ball, the outer area of which 
shows radiating lines of spores. These are clear and highly refrac- 
tile. Their diameter varies from 2.5 to 3.5 microns. ‘The color of 
the growth changes with age, succeeding from white to greenish and 
later, in old cultures, to a brownish color. The spores are quite re- 
sistant. They are not destroyed by heating at 65° C. for a period 
‘of seven hours and require an exposure of 12 hours to a 5 per cent 
solution of carbolic acid for their destruction. In the dried state, 
they are very resistant and may germinate after several months or, 
even several years when conditions are favorable. 
Pathogenicity. Of the aspergillus group, A. fumigatus is the 
most pathogenic to birds. A. nigressens, A. glaucus and A. candidus 
are less pathogenic in the order named. 
All species of birds are apparently susceptible to infection. Do- 
mesticated ones, especially those confined in large flocks and exposed 
to moldy organic matter, are most often affected. These include 
chickens and pigeons. Young chicks frequently are attacked by an 
acute form known as brooder pneumonia. Cage birds, particularly 
those in zoological gardens, are often fatally affected. In France 
thousands of pigeons are fed by men in a manner similar to the 
method used by parent pigeons in feeding their young; viz., loading 
the mouth with grain and fluid and passing it directly to the mouth 
of the pigeon. Among these men severe cases of pulmonary aspergil- 
losis occur as a result of their exposure to contaminated grain. 
The disease may be transmitted artificially to animals and birds 
by inoculation or by causing the organism to be inhaled. Inocula- 
tion of small quantities of spores into the veins or peritoneal cavity 
of rabbits, guinea pigs, fowls, or pigeons causes death from septi- 
cemia in from 24 hours to 1 or 2 weeks. In the older cases necrotic 
areas are present in the visceral organs and the aspergillus fungus 
is readily isolated from these. Lesions resulting from inhalation 
infection are usually confined to the air passages. owls and ani- 
mals exposed in rooms to dust or rye flour containing aspergillus 
spores, have contracted the disease and died as a result. 
Aspergillosis in the ostrich is discussed on pp. 228 and 229. 
Mortality. Fatalities may be high in broods of chicks that have 
been extensively exposed to infection. Those attacked apparently 
all succumb. Older birds are quite resistant. Evidence points to 
the conclusion that once the disease is established in the system a 
fatal termination follows. 
Symptoms. Considerable variation in the external signs of as- 
