MICROSPORIDIA 



669 



sporoplasm and the polar filament, a very long delicate filament. 

 The latter may be enclosed within a polar capsule as in a myxo- 

 sporidian spore. Structure of microsporidian spores (Leger and 

 Hesse, 1916a; Kudo, 1920, 1921, 1924b; Kohler, 1921). 



When such spores are taken into the digestive tract of a specific 

 host (Fig. 288), the polar filaments are extruded and perhaps anchor 

 the spores to the gut-epithelium (a). The sporoplasms emerge as 

 amoebulae through the opening after the filaments become com- 

 pletely detached (b). By amoeboid movements they penetrate 

 through the intestinal epithelium and enter the blood stream or body 

 cavity and reach the specific site of infection (c). They then enter the 



Fig. 288. The life-cycle of Stempellia magna, XS00 (Kudo), a, b, ger- 

 mination of spore in the mid-gut of culicine larva; c-k, division stages; 

 1-p, sporont formation; q-t, formation of 1, 2, 4, and 8 sporoblasts; 

 u, sporoblast; v-x, development of sporoblast into spore. 



host cells and undergo multiplication at the expense of the latter {d- 

 n). The trophozoites become sporonts (o), each of which produces a 

 number of spores (p-x) characteristic of each genus. Some spores 

 seem to be capable of germinating in the same host body, and thus 

 the number of infected cells increases. When heavily infected, the 

 host animal dies as a result of the degeneration of enormous numbers 

 of cells thus attacked. Such fatal infections may occur in an epidemic 

 form, as is well known in the case of the pebrine disease of silkworms 



