SUMMARY
From a human case of pulmonary allescheriasis, two morphologically distinct strains of Allescheria boydii [=Monosporium apiospermum] were isolated. One, a wild-type strain designated as gray, produces abundant conidia and cleistothecia; the other, a variant designated as white, produces much less conidia, more abundant aerial hyphae, and no cleistothecia. The self-sterile variant apparently has arisen as a result of in vivo mutation. The hyphal cells, conidia, and ascospores of A. boydii are uninucleate.