Lehman: Penicillium spiculisporum 



269 



by P. luteum Zukal (n), P. avellaneum Thorn and Turreson 

 (12) and the species herein described. Its morphology, the pro- 

 duction of transient yellow color in limited areas on certain 

 media, and the general production of yellow associated with 

 perithecia on potato plugs seem to place P. spiculisporum in the 

 luteum-purpurogenum series as defined by Thorn ( 1 ) . 



Description of the Organism 



Conidia sown on potato or bean agar and kept at 28 0 C. 

 germinate in great numbers within ten hours by first swelling, 

 then putting out one to three tubes (Fig. 18). These hyphae 

 rapidly branch, and, by the end of 48 hours, form a growth 

 easily visible to the eye. From these centers low spreading 

 colonies' develop with white floccose surface consisting of aerial 

 mycelium bearing a sparse crop of conidiophores as short lateral 

 branches. The mycelium is hyaline, septate, branched, often 

 forked at the apex, 2-3.5^ in diameter (Fig. 1-3). Numerous 

 perithecial initials may appear within two weeks, giving the sur- 

 face a granular appearance. White is the predominating surface 

 color, but this may change to cream, yellow or pinkish as the 

 perithecia mature. The yellow color is often transient, fading 

 again to white or cream. Infrequently in tube cultures, portions 

 of the surface are made to appear gray by a profuse development 

 of conidia. 



Conidiophores are short, 10-50 //, by 2-2.5 /x, usually 14-20 [x 

 long, and bear a single verticel of three to five conidiiferous cells 

 (Figs. 9-12). Occasionally there are only one or two or as 

 many as six conidiiferous cells in a verticel (Fig. 5-8). Fre- 

 quently the conidiophore produces a side branch bearing a single 

 chain of conidia (Fig. 13) or, less frequently, it may carry at its 

 summit two metulae each of which bear verticels of three to five 

 conidiiferous cells (Fig. 14). If the conidial fructification oc- 

 cupies the end of an aerial hypha, the conidiiferous cells may be 

 loosely disposed over a distance of 40-50 /x back from the apex 

 (Fig. 15). 



Conidiiferous- cells are 11-16/x long by 1.8-2.5 fi in diameter 

 at the thickest part, the distal third of each cell tapering to a 



