334 



PNEUMONOMVCOSIS 



For ordinary use potato, with or without glycerin, gives 

 excellent results. A paste made by rubbing up crumbs of 

 stale bread in water is also a good medium. Growth is said 

 to be more rapid, however, in Raulin's fluid than in any other 

 medium, the mycelium appearing in from five to twelve hours 

 and spores forming in from twelve to fifteen hours. The 

 growth is first a velvety white, soon becoming a delicate bluish 

 green, which grows darker. On Raulin's fluid it changes 

 after some days to a dark brown. Cultures on potato retain 

 the green color for a long time, while those on bread paste 

 become brown. 



The fungus retains its vitality in cultures for many 

 months unimpaired. Its development has been reported when 

 inoculated from cultures three or four years old. Spores do 

 not form in a temperature below 20° C. and like the mycelium 

 they require fresh access to oxygen for their best development. 

 They measure 2.5 to 3/^ in diameter. In nature the spores are 

 widely distributed but seem to be especially abundant in grain 

 and vegetable matter. They have considerable power of re- 

 sistance to heat and to chemical 

 agents. They are killed by a tem- 

 perature of 60° C. in five and one- 

 half hours. In moist heat and in 

 solution of bichloride of mercury i 

 to 1,000 the}' are destroyed in 

 fifteen minutes. 



Aspergillus fumigatus is dif- 

 ferentiated from other species by its 

 color in cultures, the high tempera- 

 ture at w^hich it grows, the size of 

 the spores and by its pathogenesis. 

 Aspergillus glauais is the one most 

 likely to be confounded with it. It 

 may be differentiated from A . fumi- 

 gatus by its ability to grow at low temperature, its delicate 

 green color, the large diameter of its spores — 9 to i5/< — and its 

 lack of pathogenic power. 



Fig. 86. Aspergillus fumi- 

 gatus in fruit. 



