178 R. KUDO 



Further reaction on the part of the host tissue against the par- 

 asites was noticed in the case of the nymph of Baetis. The 

 blood-cells of the infected nymph contained from one or two to 

 several spores of Nosema baetis. In Giemsa stained sections, none 

 of them harbored young stages of parasites; all of the parasites 

 found in the blood-cell were mature spores which were plainly 

 demonstrated by the typical staining. If the parasites attack 

 the blood-cells, one would expect to see schizonts and young 

 spores in some of the newly infected corpuscles. Judging from 

 this fact, the presence of the parasites in the blood-cell must be 

 attributed to the active phagocytosis of the host cell. Although 

 the actual processes were not seen, it is most probable that the 

 blood-cells take in the spores which have been liberated in the 

 body cavity by the rupture of the cell membrane of the infected 

 fat bodies. Similar phagocytosis was reported in four cases. 

 Sasaki ('97) held that the presence of spores of Nosema bombycis 

 in the blood-cell of Bombj^ mori was due to the phagocytosis of 

 the latter. CauUery and Mesnil ('99) in Glugea laverani, Mra- 

 zek ('99) in Glugea lophii, and Weissenberg ('13) in Glugea 

 anomala noticed phenomena of apparently similar nature. 



THE SIGNIFICANCE OF THE MICROSPORIDIAN PARASITES AMONG 

 SOME AQUATIC INSECTS 



Strickland ('13) had called attention of economic entomologists 

 to the subject in connection with the microsporidian para- 

 sites of Simulium larvae. Although the data which would enable 

 the writer to discuss the subject more fully are at present insuf- 

 ficient, the observations which have been recorded in the previ- 

 ous pages lead one to consider the significance of the microspori- 

 dian infection among the aquatic larvae of some harmful insects 

 such as mosquitoes. 



If one can increase the number of cases of Thelohania-infection 

 in mosquito larvae in the laboratory (which does not seem to be 

 impossible) one may be able to use the microsporidian parasites 

 as one of the natural enemies of mosquito larvae, by distributing 

 the infected larval tissue in the mosquito-breeding places. 



In a large body of water one can rely on fish to a greater extent 

 for the destruction of the mosquito larvae. In a smaller body 



