28 THE ANIMAL PARASITES OF MAN 



by firmer axes, which exhibit no tendency to anastomosis ; there is a 

 contractile vacuole ; one or several nuclei. Live in fresh water. 

 Order 4. Radiolaria. The body has radially-disposed filamentous pseudo- 

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

 always a siliceous framework, consisting of pieces arranged radially, 

 tangentially, or lattice-like ; there is no contractile vacuole, but fluid- 

 containing hydrostatic vacuoles are present in the peripheral protoplasm. 

 Marine. 



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

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

 function is to take in food. Cvtostorne and contractile vacuole mav be present. 

 Maybe either naked or provided with protective coverings; one or more nuclei. 

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



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

 Euflagellata, with the Protomonadina and Polymastigoda are of interest here. 



Class Iff. 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 ectoplasmic layer, or cuticle ; they have no cilia in the adult 

 state, but may 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 sporocysts, is characteristic. 

 Sub-class i. Telosporidia. These are usually of constant form, rarely amoeboid ; 

 they are uninucleate in the mature state; they live within host cells in the 

 first stage. Spore-formation occurs at the end of the life-cycle. 

 Order i. Gregarinida. Body of a constant, usually elongate form, surrounded 

 by a cuticle, In the early stage they lead an intracellular existence; in 

 the mature stage they live within the intestine or body cavity of inverte- 

 brate animals, especially the Arthropoda, and, like intestinal parasites, 

 are provided with clinging organs. Copulation usually isogamous ; 

 the spores have coats (chlamyclospores) and usually contain several 

 minute germs (sporozoites). 



Order 2. Cocddiidea. Body of uniform spherical or oval shape : they lead 

 an intracellular life, but are not freely motile in cavities of the body. 

 Fertilization is anisogamous ; the spores have coats or shells (sporocysts), 

 and usually contain several sporozoites. Exhibit alternation of generations. 

 Order 3. Hcemosporidia. Parasites of the blood corpuscles of vertebrate 

 animals ; they exhibit amoeboid movement; fertilization is anisogamous; 

 many present alternation of generations and hosts ; spores naked. 

 Sub-class 2. Neosporidia. They are multinucleate when adult, and the form of 

 the body varies exceedingly (often amoeboid) ; spore-formation com- 

 mences before the completion of growth. 



Order i. Myxosporidia. The spores have valvular coats, with or without 

 caudal appendages, with two, rarely four, polar capsules. They live free 

 in such organs as the gall or urinary bladder, but are chiefly found in 

 connective tissue. They occur especially in fishes. 



Order 2. Microsporidia. Spores with coats or sporocysts ; no caudal 

 appendage, with one polar capsule. They usually live in the tissues of 

 Arthropoda. 



Order 3. Sarcosporidia. Elongate parasites of the muscular fibres of 

 amniotic vertebrates, on rare occasions they occur also in the connective 

 tissue ; the spores, which are kidney or sickle-shaped, are naked and 

 apparently have no obvious polar capsule. 



