MOLD OR HYPHOMYCETE GROUP 395 



is termed a head. The spores are usually colored green, brown, 

 yellow, or black, or in a few species they are colorless. They are 

 spherical or oval in shape. Their surfaces are not easily wetted; 

 they are easily detached, and are readily carried about by currents 

 of air. This explains the readiness with which birds and some 

 animals become infected in the respiratory tract when fed on 

 moldy grain or fodder. When the spores come under favorable 

 growth conditions, they germinate and reproduce the mold. 



If growth conditions are right, careful observation will enable 

 one to discover the sexual stages in the reproduction. Two 

 filaments, somewhat differentiated, begin to twist together until 

 they form a typical cork-screw. The cell contents fuse, and fer- 

 tilization is effected. A tangled mass of threads arises about 

 this cell, forming a compact layer or covering termed the peri- 

 thecium. The inclosed cell grows rapidly, and produces a con- 

 siderable number of enlarged cells, each of which eventually is 

 found to contain spores, usually eight in number. These cells 

 or sacs are called asci (singular ascus), and the spores are termed 

 ascospores. These, like the conidia, when brought under favorable 

 growth conditions, reproduce the mold. An Aspergillus may con- 

 tinue to multiply indefinitely without the sexual stage developing; 

 it is not improbable that some species have altogether lost the 

 power of reproducing other than by means of the conidia. 



Several species of Aspergilli have been described as pathogenic. 

 Doubtless, these are normally saprophytes, and only produce 

 disease under exceptional conditions. 



Aspergillus fumigattrs 



Diseases Produced. Aspergillosis of birds; pneumomycosis in 

 man and many animals. 



The occasional presence of Aspergillus in lung infections has 

 been known since early in the nineteenth century. Probably 

 Mayer and Emmet, in 1815, were the first to note its presence in 

 the lungs of a bird, in this instance a jay. Since that time the 

 organism has been reported many times. In most cases no careful 

 species determination was made, but the probabilities are greatly 

 in favor of Aspergillus fumigatus being the species responsible. 

 has been reported from the stork, raven, flamingo, 



