(iii.) ACYSTOSPORIDAE.—Cells parasitic in the blood and haematocytes of warm-blooded Vertebrates; never forming a cyst-wall before dividing; zoospores formed in the corpuscles, amoeboid. Gametocytes only forming gametes when taken into the stomach of insects. Oosperm at first active, passing into the coelom, producing naked spores which again produce a large brood of sickle zoospores, which migrate to the salivary gland, and are injected with the saliva into the warm-blooded host. _Haemamoeba_ Grassi and Feletti; _Laverania_ Grassi and Feletti; _Haemoproteus_ Kruse; _Halteridium_ Labbé.[104] B. NEOSPORIDIA.—Cells becoming multinucleate apocytes before any brood-formation occurs. Brood-formation progressive through the apocyte, not simultaneous. {98}1. MYXOSPORIDIACEAE.—Naked parasites in cold-blooded animals. Spore-formation due to an aggregation of cytoplasm around a single nucleus to form an archespore, which then produces a complex of cells within which two daughter-cells form the spores and accessory nematocysts. _Myxidium_ Bütsch.; _Myxobolus_ Bütsch.; _Henneguya_ Thélohan; _Nosema_ Nageli (= _Glugea_ Th.). 2. ACTINOMYXIDIACEAE.[105]—Apocyte resolved into a sporange, containing eight secondary sporanges (so-called spores), of ternary symmetry and provided with three polar nematocysts. 3. SARCOSPORIDIACEAE.—Encysted parasites in the muscles of Vertebrates, with a double membrane; spores simple. _Sarcocystis_ Lankester. [Illustration: FIG. 32.—_Gregarina blattarum_ Sieb. A, two cephalonts, embedded by their epimerite (_ep_), in cells of the gut-epithelium; _deu_, deutomerite; nu, nucleus; _pr_, protomerite; B^1, B^2, two free specimens of an allied genus; the epimerite is falling off in B^2, which is on its way to become a sporont; C, cyst (_cy_) of A, with sporoducts (_spd_) discharging the spores (_sp_), surrounded by an external gelatinous investment (_g_). (From Parker and Haswell.)]