MICROSPORIDIA 337 



charge their contents, which "weaken the activity of the epithelial 

 cell." 



As to the mechanism of the filament-extrusion, Stempell (1909) 

 maintained that the sporoplasm increases its volume by absorption 

 of water through the spore membrane and the pressure causes the 

 extrusion of the filament. Kudo (1918) held that probably "a 

 physical force, comparable to that produced by pressure, develops 

 within the spore and expels the polar filament. This force may be 

 none other than the gas evolved through the decomposition of 

 hydrogen peroxide by the peroxydase contained within the spores." 

 Morgenthaler (1922) holds that since the water is capable of 

 causing the extrusion of the filament, there may be in the polar 

 capsule a substance which increases its volume by absorbing water 

 and this results in the filament-extrusion. 



4) The spore-mcmbranc. In the majority of microsporidia, the 

 spore membrane seems to be of a single piece. A longitudinal line 

 which was recognized as the sutural line of the two valves of the 

 spore-membrane was noted, however, in Glugea anomala, Thelo- 

 Jiania giardi (Thelohan), Plistophora s'unuli (Lutz and Splendore), 

 P. sp. (Mercier), P. hlochmanni (?) ( Georgevitch, 1929) and 

 Thclohania opacita (Kudo). From this brief summary it would 

 seem that the majority of microsporidian spores possess a spore- 

 membrane of a single piece, while in a few species, the spore- 

 membrane is apparently composed of two valves. 



5) The dimorphism of the spore. As was stated briefly in the 

 section on the spore, a number of observers noted a dimorphism in 

 the microsporidian spore. Leger (1897) noticed two types of spores 

 in Thclohania varians with regard to the size, the macrospore and 

 the microspore, the former grouped in variable numbers in spher- 

 ical masses, while the latter regularly in groups of eight, sur- 

 rounded by a membrane. 



a) Cases of dimorphism. The following species are known to 

 show a more or less regular dimorphism of the spores : Plistophora 

 mirandellcB (Vaney and Conte), Thelohania janiis (Hesse), T. 

 opacita (Kudo), Gurleya richardi (Cepede), Plistophora longifilis 

 (Schuberg), P. hitfonis (Guyenot and Ponse, 1926) and P. hloch- 

 manni (?) (Georgevitch, 1929). 



b) Is there any structural difiference between the macrospore and 

 microspore? Hesse (1903) found in Thclohania janus that the 

 macrospore did not possess the polar filament which was present 



