FAMILY IV. ACTINOPLANACEAE 



829 



or on short lateral branches, a few to many 

 sporangia on one hypha; they are formed 

 in the hj^phal tufts and mounds until the 

 latter may be almost solid masses of spor- 

 angia. The sporangia are white in small 

 groups, pink in large masses and spherical, 

 measuring 7 to 19 microns in diameter on 

 leaves, most measuring 8 to 9 microns. 

 Shortly after their formation, spores are 

 visible as a single coil in each sporangium; 

 when completely formed, they are irregu- 

 larly arranged. Immersion of the mature 

 sporangium in water brings about the swell- 

 ing of an intersporal substance; this swelling 

 causes the wall and the spores to push out 

 on one side forming a cone-shaped projec- 

 tion about half as long as the diameter of 

 the sporangium. The spores are forcibly 

 ejected through an opening in the cone; 

 they are spherical, 1.8 to 2.0 microns in 

 diameter, possess a shiny globule and are 

 non-motile. The sporangial wall persists for 

 several hours after spore discharge. In addi- 

 tion to sporangia, conidia are formed in 

 coils somewhat as in Streptomyces , though 

 the coils are much less conspicuous. 



Czapek agar: Growth fair, about 0.7 to 

 1.2 cm in diameter after 6 weeks; usually 

 flat, level with agar surface; concentric 

 zonation distinct or absent; central region 

 usually compact with a broad fringed border 

 and a tasseled edge. Surface glossy or pow- 

 de^3^ Color usually white, sometimes pink- 

 ish buff or cream-buff. Sporangia, absent 

 to fairly abundant, are always formed some 

 distance above the surface of the agar. In 

 some cultures coils are formed which break 

 up into conidia as in Streptomyces. Palisades 

 are absent. 



Peptone Czapek agar: Growth good, a- 

 bout 1.5 to 2.0 cm in diameter after 6 weeks; 

 flat or with a few low radial or irregular 

 ridges and grooves; margin fringed or en- 

 tire; aerial hyphae often formed in white 

 concentric rings, sometimes as a white bor- 

 der and sometimes giving a powdery ap- 

 pearance to the normally glossy surface. 

 Olive-buff to deep olive-buff. Sporangia 

 very rare. 



Potato glucose agar: Growth usually 

 good, 1.0 to 1.8 cm in diameter after 

 2 months; center elevated with irregular 

 bumps and ridges; margin flat and even 

 with surface of agar. Color at first creamy, 

 becoming tawny and then Carob brown or 

 Kaiser brown, after which white floccose 

 spots of hyphae appear, usually spreading 

 to cover the entire culture. Sporangia are 

 usually formed in vast numbers, the white 

 areas becoming rosy pink as the sporangia 

 mature; the pinkish areas are frequently 

 minutely pocked. Surface moist at first, 

 appearing dry and floccose as aerial hyphae 

 and sporangia are formed. Agar colored 

 reddish brown with a vinaceous tinge. 



Agar: Growth fair, 0.7 to 1.3 cm in diame- 

 ter after 2 months; central region elevated 

 into irregular ridges which merge, towards 

 the outside, into radial ridges and grooves 

 sloping abruptly to the narrow, flat border; 

 margin lobed. Usually cream-buff, rarely 

 buffy brown. Surface usually glossy, some- 

 times powdery with aerial hyphae which 

 may be united to form many upright fasci- 

 cles. Sporangia absent. 



Krainsky's glucose asparagine agar: 

 Growth poor, 0.3 to 0.7 cm in diameter; 

 slightly elevated and minutely ridged, slop- 

 ing to the fimbriate margin. Surface of cen- 

 tral region minutely powdery with aerial 

 hyphae. White. Sporangia absent. 



Emerson's agar: Growth good, about 2 cm 

 in diameter after 6 weeks, composed of a 

 whitish central area, 4 to 6 mm wide, made 

 up of elevated, irregular bumps and ridges 

 which abruptly change into radial ridges 

 and grooves sloping down to a flat, white 

 border, 1 to 2 mm wide and composed of 

 minute, concentric circles of white hyphae. 

 Ridges and grooves vinaceous brown, some- 

 times covered with a whitish down. Margin 

 smooth or scalloped, ending abruptly. Sur- 

 face dry. Sporangia formed abundantly, 

 appearing first in the center as the white 

 changes to pink. Agar colored pale vina- 

 ceous brown. 



Habitat: Found in vegetable garden soil, 

 Chapel Hill, North Carolina. 



