Cytoplasmic organization and symbiotic associations of Didymocyrtis tetrathalamus (Haeckel) (Spumellaria, Radiolaria)

摘要

Cytoplasmic organization and symbiotic associations of Didymocyrtis tetrathalamus (Haeckel) were examined. The most distinctive cytological feature is the presence of an extraordinary, non-living wall structure (termed endocapsular wall) that lies im- mediately inside the outer medullary shell. It closely resembles the capsular wall, which is the most diagnostic feature for radiolarian cy- toplasmic organization, but is completely enclosed by the latter wall. The capsular wall lies inside the cortical shell, except in the polar region where the wall is always outside the latticed skeleton of the bilocular cortex.