Abstract
Each of the 100+ spore initials in the ascus of D. tothii are delimited from the ascus cytoplasm by a double, delimiting membrane, herein called the spore vesicle, after the completion of nuclear divisions. An ascus vesicle is not formed. Unidentified, osmiophilic bodies, probably lipoidal in nature, are common in the ascus cytoplasm throughout ascosporogenesis and may play a role in spore ontogeny.