MORPHOLOGY AND DESCRIPTION 



19 



outer surface of the wall is free from pits, warts, or roughenings, hence is 

 called smooth; its structure is difficult to differentiate; the mass of the cell- 

 wall appears homogeneous or nearly so under the microscope and does 

 not absorb the ordinary protoplasmic stains. In some species the inside 



* 



■s, %. ^ W g§- — - Comd,a - ■ 



III gU# 



Fig. 3. A, Aspergillus niveo-glaucus, NRRL No. 127, typical head showing only 

 one series of sterigmata, X 575. B,A. versicolor, NRRL No. 239, typical head show- 

 ing sterigmata in two series, X 1200. 



surface of the wall shows irregular clumps or uneven thickenings. When 

 broken, many of these conidiophores show uneven or jagged ends like a 

 broken glass tube; in the A. niger group the broken ends split like bundles 

 of laths (fig. 64 B), giving a possible clue to the method of their formation. 

 In the second section, the wall appears dotted or pitted, or as interpreted 



