534 



NEOSPORIDIA 



myxomatous in places, and cellular at other spots. The cysts were 

 found to be oval, round, tubular, branched or irregular bodies, lying 

 below the epithelium principally, but also found in haemorrhages 

 and in cell collections. The wall of the cyst is generally thin, and 

 has either an opening or a conical elevation at one point. It con- 

 sists of two layers — a thinner external and thicker internal coat. 

 The smaller cysts, from lo to 30 jll in diameter, contained undiffer- 

 entiated protoplasm with a vesicular nucleus containing a nucleolus. 

 The larger cysts had one or more definite chromatic masses. A 

 fully-developed cyst is lined with protoplasm, in which young pan- 

 sporoblasts are forming, while the centre of the parasite is full of 

 old pansporoblasts, separated from one another by an indefinite 

 framework continuous with the capsule. A young pansporoblast 

 is seen to be a small oval or rounded mass of cytoplasm with a 

 single nucleus. This body grows, and becomes surrounded by a 

 membrane, while its nucleus divides by amitosis into four to sixteen 

 spores, each of which has a very thin wall and a central nucleus. 

 The pansporoblasts and spores are set free by rupture of the cyst, 

 and may be surrounded by polymorphonuclear leucocytes, thus 

 forming minute abscesses, or may be engulfed by mononuclear 

 leucocytes, or may grow into parasites, or escape from the host in 

 the nasal secretion. The method of infection is not known. 



The framework inside the cyst separating the pansporoblasts 

 indicates that Rhino sp or idium belongs to the Sarcosporidia, and not 

 to the Haplosporidia. 



Pathogenicity. — -The pathology appears to be a proliferation of 

 the submucosa and mucosa of the nose, brought about by the 

 irritation of the parasite (see p. 1578). 



ORDER IV. HAPLOSPORIDIA Caullery and Mesnil, 1899. 

 Synonym. — Haplospovidiidea Poche, 1913. 



Neosporidia with very simple life-history and undifferentiated cell-plasma, 

 without septum and with spores of simple structure, with one nucleus, and 

 no polar capsules. 



The Haplosporidia are characterized by the simplicity of their life-cycle, 

 which begins with a mononuclear or binuclear trophozoite, which may encyst, 

 and in any case grows larger and larger, while its nucleus divides into several 

 nuclei, so that a multinucleated mass or schizont is formed. This escapes from 

 its cyst and divides up into merozoites, either directly or after plasmotomy, 

 each of which becomes a trophozoite, thus completing schizogony. Sporogony 

 is unknown. 



They are parasites of fishes and invertebrates. 



Classification. — Family i. HAPLospoRiDiiE Caullery and Mesnil. — Spores 

 with double envelope and opening. 



Genus 1. Haplosporidium. — Spores closed by a valve. In annelids. 

 Genus 2. Urosporidium. — Spores open. In annelids. 



Family 2. Bertramiid^. — Spore envelope without opening. 

 Genus i, Bertramia. — Stomach of fish. 



Genus 2. Ichthyosporidium. — In tumours of fish (Figs. 191-196). 



Family 3. CoiLQSPORiDiiD^.. — Spores nude. 

 Genus 1. Polagarynum. 

 Genus 2. Blastulidium, 



