THE GENUS ASPERGILLUS. 



37 C. It is frequently observed in cases of mycosis of the human 

 ear (where it is sometimes confounded with A. glaucus), and also 

 occurs on bread, portions of plants, and dried excrement. Even 

 at blood temperature it thrives luxuriantly on all kinds of myco- 

 logical substrata, and rapidly produces extensive yellow-green 

 growths of mould. The 

 superficial colour is rarely Q 

 pure yellow, and the older 

 growths (several weeks or 

 months) are very liable to 

 turn colour, becoming finally 

 an ugly dark brown. The 

 conidiophores (Fig. 170), 

 which generally measureless 

 than i mm. (0.5-0.7 mm.), 

 carry a spherical or club- 

 shaped globule, which rarely 

 springs in a sharply defined 

 manner from the pale, warty 

 stem ; and the simple, slen- 

 der sterigmata, which are 

 generally disposed radially, 

 though sometimes confined 

 to the summit, develop 

 large conidia (average 56 yu 

 in diameter), which are 

 generally of an irregularly 

 globular shape, and smooth 

 (sometimes finely granular), 

 separate, by constriction, 

 into chaplets, which readily 

 become dissociated. The 

 coloured heads measure up 

 to about 90 /j,, the globules 

 30-40 p. in diameter, the 

 sterigmata usually about 

 20-60 fji. The conidia vary 

 between 4 and 8 fj. in dia- 

 meter, but in any event 



the species (with A. glaucus and A. oryzf?) belongs to the large- 

 spored class. No perithecia have been observed, but WILHELM (I.) 

 in 1877 described small, black, nodular sclerotia (about 0.7 mm. 

 in diameter), with a thick skin and pale core, which remained 

 sterile in germination tests. These appear to be formed by 

 simple intertwining and fusion of morphologically uniform 

 filaments. Further morphological details are furnished by 

 WILHELM (I.), SIEBENMANN (I.), and WEHMER (XVII.). 



According to NOMURA (I.), this fungus is the chief source of 



FIG. 170. Aspergillus flavus. 



Couidiophores with spherical to club-shaped 

 globules and simple sterigmata (1-4), the 

 outer wall of the (frequently septate) stem 

 being roughened by colourless granules (5). 

 6. Conidial herbage (about 2/1). 7. Conidia. 

 Magn. of 1-4, 140 ; of 5, 400 ; of 7, 500. 

 (After Wehmer.) 



