230 PNEUMOMYCOSIS 



development. They measure 2.5 to 3/i in diameter. In 

 nature the spores are wide!}' distributed but seem to be 

 especialh' abundant in grain and vegetable matter. They 

 have considerable power of resistance to heat and to chemical 

 agents. They are killed by a temperature of 60° C. in five 

 and one-half hours. In moist heat and in a solution of 

 bichloride of mercury i to 1,000 thej- are destroyed in fifteen 

 minutes. 



Aspergillus fumigatns is differentiated from other species 

 b}^ its color in cultures, the high temperature at which it 

 grows, the size of its spores and by its pathogenesis. Asper- 

 gillus glaums is the one most likely to be confounded with it. 

 It may be differentiated from A. fumigahts \>y its abilit}- to 

 grow at low temperatures, its delicate green color, the large 

 diameter of its spores — g to 15// — and its lack of pathogenic 

 power. 



The mode of infection is through the respiratory tract. 

 Only a small number of the spores inspired are able to reach 

 the alveoli, the greater number of them being arrested in 

 the tracheal and bronchial secretions. Hildebrant has shown 

 that, having reached the alveoli, thej' penetrate the epithelial 

 lining without difficulty. Both animals and man seem to 

 possess immunity to intestinal infection. Renon has produced 

 it only a few times experimentally. 



The aspergillus does not form a toxin. Its pathogenic 

 power is due entirely to lesions produced by the masses of 

 mycelium which cause a necrosis of the cells and a leucocytic 

 reaction which diminishes the functions of the organs, the 

 final result being an enfeebled condition of the animal and a 

 lessened resistance to hurtful influences. When fruit hyphae 

 can form, the myriads of spores given off b}' them may be 

 carried to other parts of the organ. In this way the foci 

 rapidly multiply and practically' the entire organ becomes 

 invaded. The opinion held by some authors that in the mould 

 niA'coses there is "no fructification or actual multiplication" 

 of the infecting agent and that the "number of the diseased 

 foci corresponds exactly with the number of spores introduced' 

 is erroneous both for the disease naturally contracted as well as 



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