[Ultrastructure of Cl. oedematiens spores]

As a result of study of the ultrastructure of Cl. oedematiens, type B it was found that the first signs of spore formation were anlage of the prespore membrane by invagination of the cytoplasmic membrane. The prespore forms later; the cortex forms between the external and the internal layers of the prespore membrane. Internal spore coat forms by joining of the osmiophilic plates, and exosporum forms simultaneously with the spore coat and is localized externally. Mature spores consist of sporoplasm covered with a membrane, light cortex, external and internal spore coat and and interstitial layer between them and the exosporium.