28 THE ANIMAL PARASITES OF MAN 



Order i. Amcebina (Lobosa) naked or with a simple shell, sometimes 

 formed of a foreign substance ; the pseudopodia may be lobu- 

 lated or finger-shaped ; there is a contractile vacuole ; generally only 

 one nucleus. They live in fresh or salt water, in the soil, and 

 also parasitically. 



Order 2. Foraminifera (Reticularia). Mostly provided with a chalky 

 shell, usually consisting of several chambers, and allowing the pro- 

 trusion of the pseudopodia either at the periphery or only at the 

 opening. The pseudopodia are filamentous and frequently anasto- 

 mosed ; there is no contractile vacuole ; there are usually several 

 nuclei. Marine. 



Order 3. Heliozoa. Naked, with a chitinous or simple radial chalky frame- 



' work ; the pseudopodia are filamentous, and are frequently supported 



by firmer axis filaments, which exhibit no tendency to anastomosis I 



there is a contractile vacuole ; one or several nuclei. Live in fresh 



water. 



Order 4. Radiolaria. The body has raflially-placed filamentous pseudo- 

 podia, and the nucleus is hidden in the central capsule ; there is 

 almost always a silicious framework, consisting of pieces arranged 

 radially , tangentially, or lattice-like ; there is no contractile 

 vacuole ; but there are always vesicular vacuoles in the peripheral 

 sarcode. Marine. 



Class II. Flagellata (Mastigophora). Protozoa with one or several long 

 flagella used for locomotion and for acquiring food ; in stationary forms their 

 only function is to draw in food ; cytostom common, contractile vacuole 

 always present. May be either naked or provided with shells and shelters ; 

 one nucleus only. They live either in fresh or salt water, or may be parasitic. 

 This class is again divided into several sub-classes or orders, of which only 

 the Euflagellata, with the Monadihes and Polymastigodes, are of interest here. 

 Class III. Sporozoa. Protozoa that only live parasitically in the cells, 

 tissues, or organs of other animals ; they ingest liquid food by osmosis ; 

 the surface of the body is covered with an ectoplasmatic layer, or cuticle ; 

 have no cilia in the adult state, and rarely form pseudopodia ; flagella 

 occur, but only on the male propagating individuals. There may be one 

 or numerous nuclei, but no contractile vacuole. Propagation by means of 

 spores, mostly provided with shells, is characteristic ; division and budding 

 seldom occur, but alternation of generations is frequent. 



Sup-class T. Telosporidia (Cytosporidia) are usually of one constant form, 

 rarely amoeboid ; are always mononuclear in the mature state ; 

 they live within cells in the first stage. Sporulation at the end 

 of life. 



Order i. Gregarinida. Body of a constant, usually elongated form, 

 surrounded by a cuticle. In the early stage they lead an intra- 

 cellular existence ; in the mature stage they live within the intestine 

 or abdomen of invertebrate animals, especially the arthropoda, 

 and, like intestinal parasites, are provided with clinging organs. 

 Fecundation isogamic ; the spores have shells, no polar bodies, 

 and usually contain several minute germs (sporozoites). 

 Order 2. Coccidiida (Coccidiomorpha). Body of uniform spherical or 

 oval shape ; intracellular life, but are not freely motile in cavi- 



