344 RESEARCH IN PROTOZOOLOGY 



Any attempts to generalize schizogonic changes as reported by 

 various investigators will at present only increase the confusion 

 which already exists. Careful cytological studies of species in which 

 large schizonts occur are greatly desired. 



12) Problems in sporogony. As was stated above, schizogony 

 terminates when each schizont transforms itself into a sporont, 

 with or without nuclear fusion. In two cases (Thelohania 

 giardi after Mercier; Plistophora (Glugea) danilewskyi after 

 Guyenot and Naville), however, the sporont is said to be produced 

 by a union of two gametes. 



Each sporont gives rise to one, two, four, eight, sixteen or more 

 sporoblasts according to various genera (Kudo, 1924: 65-69). The 

 nuclear division which takes place in the course of sporoblast 

 formation appears to be amitotic in numerous species. In some 

 species of Thelohania, typical mitotic figures were observed. It 

 appears to be seen clearly in the species of this genus parasitic in 

 the larvae of dipterous insects (Debaisieux, NoUer, Kudo). In 

 Thelohania legeri, the writer saw in the first nuclear division of 

 the sporont that the nucleus undergoes a spireme stage, fol- 

 lowed by the appearance of chromosomes ("pseudochromosomes'' 

 of Debaisieux, 1928) and spindle fibers, and the disappearance 

 of the nuclear membrane. The number of the chromosomes could 

 not be made out distinctly, but it appeared to vary from six to ten 

 and in anaphase eight were fairly regularly made out. In T. midti- 

 spora, Debaisieux and Gastaldi noted eight chromosomes at the 

 equatorial plane, and eight or nine at telophase, and in a later 

 paper, Debaisieux (1928) stated that at each pole in telophase he 

 counted eight or nine chromosomes in the first and five in both 

 second and third nuclear divisions. The spindle fibers were very 

 distinct. 



As to the development of the sporoblast into a spore, there are 

 various observations. 



a) Leger and Hesse (1907) remarked briefly that the spore of 

 Nosema bombycis possesses two cells for the spore membrane, a 

 polar capsule with a small nucleus and a mono- or binucleated 

 sporoplasm. Stempell (1909) in the same species and Mercier 

 (1909) in Thelohania giardi observed that the nucleus of the 

 sporoblast divides into five nuclei, of which two form the spore 

 membrane, one the polar capsule and the filament and two the 

 sporoplasm. The same view was expressed by Fantham and 



