572 A MANUAL OF THE PENICILLIA 



a peridium of specially differentiated cells. As in other members of the 

 series, the perithecium appears to be bounded by a network of interlacing 

 hyphae. The pattern of the perithecial initials has not been estabhshed 

 since these structures regularly develop in areas of comparatively dense 

 growth well within the margin of established colonies. Asci are borne as 

 lateral buds from fertile hyphae as in P. luteum and P. striatum. Asco- 

 spores are large, elliptical, show no evidence of an equatorial furrow, and 

 are delicately pitted over their entire surface. 



Penicillium striatum Raper and Fennell is doubtfully a member of the 

 P. luteum series, but can be keyed here more satisfactorily than elsewhere. 

 Certain of its characteristics indicate a considerable measure of true rela- 

 tionship. This is suggested particularly by the character and texture of 

 its perithecia, which strongly resemble those of P. luteum and P. wortmanni 

 except for a lack of yellow pigmentation in the coarse enveloping hyphae. 

 Asci are borne as lateral buds from ascogenous hyphae (fig. 157E) and in 

 size, shape, and mode of origin bear a striking resemblance to P. avellaneum 

 considered above. The ascospores are unique in the pattern and degree of 

 their markings. They are broadly elliptical, and smooth- walled except 

 for a series of thin, comparatively wide, wavy, longitudinal ridges or frills 

 (fig. 157F) which tend to converge at opposite ends of the spore. There is 

 no suggestion of an equatorial band. Penicilli are comparatively scarce 

 and inconsistent in pattern, hence offer little help as a possible clue to rela- 

 tionship. Symmetrically-biverticillate structures have not been observed, 

 nor are the sterigmata lanceolate-acuminate in the manner typical of the 

 Biverticillata-SymLmetrica. At the same time they are not sufficiently 

 characteristic of any other group in the genus Penicillium to suggest more 

 accurate placement elsewhere. Continued examination of newly isolated 

 ascosporic Penicillia may in time reveal transitional species or otherwise 

 provide a satisfactory basis for correct placement of this species. Until 

 that time, we believe it is best to retain it here where it can be found with 

 other forms which at least produce an ascosporic phase possessing certain 

 similarities. 



Members of the Penicillium luteum series as it is here constituted are 

 by definition, typically ascosporic. Individual strains belonging to differ- 

 ent member-species, however, commonly lose their capacity to produce 

 perithecia and ascospores, and subsequently may be perpetuated in labora- 

 tory culture without the reappearance of this developmental phase. While 

 it is possible that these represent unisexual haplonts, and that by proper 

 pairing of such asexual strains the capacity to produce perithecia might be 

 restored, such attempts have been consistently unsuccessful in our ex- 

 perience. Emmons (1935) reported all of the species studied by him, in- 

 cluding P. wortmanni Klocker, P. veryniculatum Dangeard, P. spiculi- 



