MICROSPORIDIA. 



347 



The life-history of Stempellia magna, as described by Kudo, 

 may be regarded as typical. When the spore reaches the 

 mid -gut of the CuHcine host, the polar filament is extruded, 

 the unicleate sporoplasm creeps out, enters a fat-cell, and 

 reproduces by division (fig- 171, A). The products of this 

 division become multinucleated, with four to eight nuclei (B) 

 These chains then break up into binucleated cells, the nuclei 

 of which discard some chromatin and fuse together in pairs (G) 

 The sporonts thus formed may give rise to a single spore (D) 

 or divide to form two (E), four (F) or eight (G) sporoblasts 



Fig. 171. — Diagram showing the probable development of a typical 

 Microsporidian, Stempellia magna Kudo, X 800. A, amoe- 

 bula coming out from the spore in the mid-gut of Culi- 

 cine larva; B, stages in schizogony or nuclear increase ; 

 C, sporont formation ; D-G, formation of one, two, four 

 or eight sporoblasts ; H, transformation of a sporoblast 

 into a nucleated spore with polar capsiile. (After Kudo . ) 



Each of these forms a single spore after chromidia formation 

 and reconstitution of small nuclei has taken place (H). 



The Micro SPOEIDIA are responsible for causing devastating 

 epidemics in silkworms, honey-bees, and certain fishes. AH 

 the tissues of the host may become infected, and the tissue- 

 cells destroyed on an extensive scale. Many species cause 

 tumour-like masses to be formed in which the organisms may 



