342 RESEARCH IN PROTOZOOLOGY 



movements (not actually seen) in the lumen of the alimentary 

 canal, and the hemocoele, and finally enters a host cell to begin in- 

 tracellular development. By mixing fresh spores of Nosema bom- 

 bycis with a drop of the digestive fluid of healthy larvae on a slide, 

 and keeping it at the room temperature for twenty-four hours, 

 the writer noted the sporoplasm in some spores moved toward 

 the anterior end as a round or irregular mass and caused the ex- 

 trusion of the filament (Kudo, 1916). Further observation could 

 not be carried on because of the bacterial growth. Through infec- 

 tion experiments with the same microsporidian, it was found that 

 the oblong or triangular amoebula is binucleate and capable of 

 amoeboid movements judging by its irregular form. This stage 

 seemed to give rise to a uninucleate stage. The so-called planont 

 stage of Stempell was not observed. 



An infection experiment with St cm p cilia magna, led the writer 

 to state that the spores extruded the filaments in the posterior 

 region of the midgut, and the uninucleate amoebula^ creep out. They 

 are capable of amoeboid movements and penetrate through the gut 

 epithelium and surrounding tissues (manner unknown). They 

 finally enter the fat body surrounding the gut or adjacent 

 tracheae. 



Thus it is to be noted, from these small number of incomplete 

 observations on experimental infection, that when the microspori- 

 dian spore gains entrance with the food into the midgut of a suit- 

 able host, it extrudes its polar filament under the action of the 

 digestive fluid and the sporoplasm emerges through the opening 

 in the spore membrane. Although it is agreed in general that the 

 sporoplasm escapes through the foramen which was made by the 

 detachment of the extruded filament, certain authors report that 

 the emergence of the sporoplasm may take place at other places 

 (Sasaki, Paillot, Guyenot and Naville, Zwolfer). Georgevitch's 

 (1929) hypothetical figure is apparently based upon his view that 

 the spore membrane is of bivalve shell and is unfortunately not 

 based upon actual observation. It is regrettable that there is no 

 experimental observation on the emergence of the sporoplasm in 

 the spores in which the sutural line was noted. 



Stempell's view about the planont stage needs further con- 

 firmation. 



11) Problems in scliizocjony. When an amoebula enters a host 

 cell, it becomes a schizont ("meront" of Stempell). How an 



