346 RESEARCH IN PROTOZOOLOGY 



(1926), Schwarz (1929), and others. The solution of this problem 

 depends upon future investigations. 



14) Problems of the hypertrophy of the host cell nucleus. The 

 MiCROSPORiDiA have been considered to confine themselves to the 

 cytoplasm of the host cell. As a rule, the host cell nucleus becomes 

 highly hypertrophied and modified in structure. Typical examples 

 are Plistophora longifilis, Gurleya francottei, Mrazekia stricta, 

 Stempellia magna, Nosema bcetis, N. nepce, etc. 



Recently Guyenot and Ponse (1926) noted development of 

 Plistophora bufonis in the nucleus of the host's follicular cells. 

 Schwarz (1929) gives a good account as to how^ the nuclei of 

 adipose tissue and muscle cells of the host larva are attacked by 

 Nosema nonagrice and are completely destroyed. 



How is the host cell nucleus hypertrophied? If it is due to 

 certain influences of the microsporidian, as has been considered 

 the case, what is its nature? Of these we have no knowledge at 

 present. 



15) Problems of phagocytosis and other reactions on the part 

 of the host against microsporidian parasites. A number of cases of 

 phagocytosis were reported to occur (Kudo, 1924). Recently this 

 phenomenon has been observed further in Nosema binucleatum 

 (Weissenberg, 1926) and Thelohania ephcstice (Mattes, 1928). 

 Zwolfer (1926) found that when the muscle bundles of Gammarus 

 pulex are completely destroyed by Plistophora blochmanni, the 

 whole structure becomes surrounded by the host's connective tissue 

 which seems to secrete a substance which cements the microspo- 

 ridian spores and the whole assumes a dark brownish color. Good- 

 rich (1928) also noted similar conditions in Gamuiarus infected by 

 Nosema sp. and Thelohania millleri (?), and observed that the 

 dark brown coloration of the parasitic masses which replaced the 

 host tissue completely was due to the secretion of chitinoid sub- 

 stance by the phagocytes which attacked the peripheral portion of 

 the parasitic mass. Poisson (1928) noted small white or brown 

 "cysts" of Nosema nepce in the gut wall of Nepa cinerea, its host. 

 This microsporidian attacks primarily the adiix)se tissue. In the 

 brown "cyst," a number of spores are encased within an envelope 

 of connective tissue cells and leucocytes. The spores are more 

 or less degenerated and the entire mass is covered by a pigment 

 zone which was considered as degeneration product of the con- 

 nective tissue cells and leucocytes. 



