HELICOSPORIDIA 



543 



cleate sporonts become differentiated. A sporont divides apparently 

 twice and thus forms four small cells which develop into a spore. 

 The complete life-history is still unknown. 



Genus Helicosporidium Keilin. Parasitic in arthropods; schizog- 

 ony and sporogony; spore with central sporoplasms and a single 

 thick coiled filament. One species. 



Fig. 261. Diagram illustrating the probable development of Helico- 

 sporidia, X about 1600 (Keilin). a-c, schizont and schizogony; d, spo- 

 ront(?); e, three stages in formation of four-celled stage; f, hypothetical 

 stage; g, young spore before the spiral filament is formed; h, mature spore; 

 i, j, opening of spore and liberation of sporoplasms. a-h, in living host 

 larva; i, j, in dead host body. 



H. parasiticum K. (Fig. 261). In body cavity, fat body, and nerv- 

 ous system of larvae of Dasyhelea ohscura and Mycetobia pallipes 

 (Diptera), and Hericia hericia (Acarina), all of which inhabit 

 wounds of elm and horse-chestnut trees; schizonts minute; spores 

 5-6m in diameter; extruded filament 60-65/x by l/z thick. 



