MYCOSIS 559 
diagnosis than ''mould disease"; this may be in part 
due to overlooking other things, but to a much greater 
extent to the very extensive mould growth which obscures 
all other changes. That unexplained preparatory condi- 
tions may exist is indicated by general observation and 
some experimental work. Whereas in breeding estab- 
lishments this disease occurs in epizootics, or in groups 
of cases, with us it is enzootic, constantly present, never, 
however, bursting forth in virulent form with high 
mortality. Nor is the condition highly contagious. 
In an attempt to explain its source I examined over 
forty varieties of feed and found therein several strains 
of aspergillus and of mucor ; the latter occurs occasionally 
in the avian air sac. The infective material is therefore 
constantly present, and it would seem that if it were 
capable of initiating a fatal disease many more cases 
should come to our attention. Perhaps these moulds do 
gain access to the avian air sac and are killed off, or only 
assume a pathogenic role when they are in large num- 
bers or a preexisting disease assists them. Since our 
records do not support the idea that a preceding condi- 
tion must exist for a growth of mould to be successful, 
and yet pathological and experimental observations sug- 
gest that something helps its colonization in the air sac, 
what are such conditions? Moulds grow on feed and lit- 
ter in which birds pick ; from this it is quite possible for 
a piece of grain or even inorganic matter laden with 
spores to be inhaled and lodged in a secondary alveolus 
near the air sac whence extension into the air spaces could 
occur. In addition I think it quite conceivable that a 
whole colony of mould might be inspired with the same 
result, the mechanical obstruction being sufficient physical 
damage to incite inflammation. The continuous moist 
surfaces of the bronchial passages and air sacs afford 
conditions favorable to the growth of mould and as 
inflammation is not vigorous, little resistance is presented 
to its spread. 
