Aleuriospores ofH.griseaare bounded by a thick, single-layered cell wall differentiated into an outer, electron-dense melanized zone and an inner, hyaline zone. Melanization was initiated at the periphery of the cell wall and progressed inwards towards the cytoplasm. To distinguish between chlamydospores and aleuriospores, the presence of a secondary cell wall in the former and the presence of a partially melanized, single-layered cell wall in the latter might prove a useful criterion in distinguishing between the two spore types. However, before such a distinction is made, similar studies on other aleuriospore-producing species are necessary.