164 



PROTOZOOLOGY 



fuse on their oral surfaces. There occur three micronuclear divisions 

 as in the case of conjugation, but there is no nuclear exchange be- 

 tween the members of the pair. The two gametic nuclei in each indi- 

 vidual are said to fuse and form a synkaryon as in autogamy. 



The paedogamy occurs in at least two species of Myxosporidia, 

 namely, Leptotheca ohlmacheri (Fig. 247) and Unicapsula muscularis 

 (Fig. 248). The spores of these myxosporidians contain two uninu- 

 cleate sporoplasms which are independent at first, but prior to 

 emergence from the spore, they undergo a complete fusion to meta- 



:^I 







^sS^?-^ 



^U 







Fig. 82. Paedogamy in Adinophrys sol, X460 (Belaf). a, withdrawal 

 of axopodia; b, c, division into two uninucleate bodies, surrounded by 

 a common gelatinous envelope; d-f, the first reduction division; g-i, 

 the second reduction division; j-1, synkaryon formation. 



morphose into a uninucleate amoebula. Perhaps the classical exam- 

 ple of the paedogamy is that which was found by Hertwig (1898) in 

 Actinosphaerhim eichhorni. The organism encysts and the body di- 

 vides into numerous uninucleate secondary cysts. Each secondary 

 cyst divides into two and remains together within a common cyst- 

 wall. In each the nucleus divides twice, and forms four nuclei, one of 

 which remains functional, the remaining three degenerating. The 

 paedogamy results in formation of a zygote in place of a secondary 

 cyst. Belaf (1922) observed a similar process in Adinophrys sol 

 (Fig. 82). This heliozoan withdraws its axopodia and divides into 

 two uninucleate bodies which become surrounded by a common 



