REPRODUCTION AND THE LIFE CYCLE 



185 



with the mvcetozoa, and tlii-ouo;li these a phylogenetic relationship 

 between the neosporidia and the rhizopoda. This is partieularly 

 well illustrated in the case of Schewiakovella schmeili, a parasite of 

 copepods where there is not only a multinucleate trophozoite stage, 

 but the parasite differs from all other sporozoa in having a distinct 

 rhizopod characteristic in its contractile vacuole, while it agrees with 

 mycetozoa in that young forms come together and fuse to form plas- 

 modia. A further "peculiarity of this organism is the binary division 

 of the spores (Fig. 77). 



In this group of little-known forms, one case of human infection 

 has been reported by Minchin and Fantham ('05). The connective 

 tissue of nasal tumors in natives of India was found to contain quan- 



FiG. 78 



Rliinosporidium kineahi, Minchin and Fantham. (.After Mint-hin and I'antham.) X 

 segment of a section througli a cyst from a tumor of the human nasal septum. The ripe 

 paiis|)oroblasts are accumulated in tlie centre of the cyst and gradually encroach upon the 

 jieripheral plasm until all is utilized. One ripe "spore-morula" is shown on the right. 



tities of haplosporidian parasites — RJiinosporulium kinealyi — in all 

 stages of devel()j)m('nt, from young multinucleate organisms to adults 

 filled with pansporoljlasts (Fig. 7S). The pansporoblasts give rise to 

 sporoblasts (spores) which are formed successively until about a dozen 

 are devel(j})ed. (As in other myxosporidian pansporoblast formation, 

 the possibility of sexual union of nuclei (autogamy) is. not excluded 

 by the iiuthors.) When mafure, the cysts aj)pear to l)urst, the mero- 

 zoites (?) thus being distributed to neighl)()ring tissues, giving rise to 

 new tumors by auto-infection. 



In .sarcosporidia, incliKhng mu.scle parasites of birds, lower mam- 

 mals and man, the process of endogenous multiplication proceeds in 

 a manner fpiite similar to that described above. In its earliest stages 

 the ]);irasi(e apj)ears as a miiiute wliite Ixxlv emlx'dded in (he matcM'ial 



