CHAPTER^XXII 

 NEOSPORIDIA 



Neosporidia — Myxosporidia — Actinomyxidia — Sarcosporidia — Haplosporidia 

 • — Protozoa incertae sedis — Chlamydozoa — Filterable viruses — References. 



NEOSPORIDIA Schaudinn, 1900. 



Definition.- — 'Parasitic plasm odromata, without motile organs, in 

 which spore-formation and trophic growth proceed simultaneously. 



Remarks. — The Neosporidia are protozoa in which reproduction 

 and growth go on together. In the Telosporidia the trophozoite 

 grows into the schizont, which divides into spores ; in the Neosporidia 

 growth and spore-formation go on together; but, as in the case of all 

 attempts at classification, there are exceptions, for the trophozoite 

 - may grow into the schizont, and then divide. 



It appears as though the Neosporidia Were evolved from a sarco- 

 dinal ancestor. 



They are divided into four orders: (i) Myxosporidia, (2) Actino- 

 myxidia, (3) Sarcosporidia, (4) Haplosporidia; and, in addition, 

 there are a number of parasites belonging evidently to the protozoa, 

 which cannot easily be classified, and are therefore placed in an 

 addendum to the Neosporidia a-s Protozoa incertce sedis. 



ORDER I. MYXOSPORIDIA Biitschli, 1881. 



Neosporidia with spore-formation commencing early in the amoeboid tropho- 

 zoite. Each spore has one or more polar capsules. 

 The Myxosporidia are subdivided into: — 



Suborder I. Phsenocystes Gurley, 1893, Synonym. — Myxosporidia {sensu 

 stricto) . Spores with two to four large, clearly visible polar capsules. 



Suborder II. Cryptocystes Gurley, 1893. Synonym. — Microsporidia (Bal- 

 biani) . Spores with one minute polar capsule, which is only rendered visible 

 by treatment with reagents. 



SUBORDER I. PHiENOCYSTES Gurley, 1893. 

 Phsenocystes comprise the true Myxosporidia, being usually found in 

 Teleostean fish, though they may occur in elasmobranchs, amphibia, and 

 reptiles. 



In fish they have long been known as psorosperms, being found in the bile- 

 passages, the urinary organs, the muscles, and the nervous system. 



The amoeboid trophozoite has a differentiation of its cytoplasm into endo- 

 and ecto-plasm, and moves about by pseudopodia. Spore-formation begins 

 early by a concentration of the cytoplasm around one of the nuclei of the 

 trophozoite. This concentrated area is marked off by a capsule, and is the 



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