[Illustration: FIG. 92.--_Theileria parva._ 1–12, intracorpuscular parasites, stained. (After Nuttall and Fantham); 13–18, Koch’s blue bodies, from stained spleen smear; 17–18, breaking up of Koch’s body. (After Nuttall.)] In the internal organs, especially the lymphatic glands, spleen and bone-marrow, are found multinucleate bodies known as Koch’s blue bodies (fig. 92, _13–18_). These are schizonts, according to Gonder.[220] The actual Koch’s blue bodies are said to be extracellular, but similar multinucleate bodies, schizonts, occur in lymphocytes. The schizonts divide and the merozoites resulting probably invade the red blood corpuscles in the internal organs. Gonder considers that the sporozoites injected by the tick collect in the spleen and lymphatic glands, penetrate the lymphocytes and give rise to the schizonts. [220] _Zeitschr. f. Infekt. paras. Krankh. u. Hyg. d. Haustiere_, viii, p. 406. Gonder has studied the cycle of _T. parva_ in the tick. He states that the gametocytes leave the host corpuscles and give rise to gametes, then conjugation occurs producing zygotes. The zygotes are then said to become active to form ookinetes, and to enter the salivary glands of the tick. Multiplication is said to occur therein, producing a swarm of sporozoites. This work needs confirmation. _T. parva_ is transmitted by _Rhipicephalus appendiculatus_, _R. simus_, _R. evertsi_, _R. nitens_, and _R. capensis_. The parasites are not hereditarily transmitted in _Rhipicephalus_, but when taken by the transmitter at one stage of its development the tick is infective in its next stage (_e.g._, if the larva becomes infected, then the nymph is infective; if the nymph becomes infected, then the adult is infective). An animal recovered from _Theileria parva_ is incapable of infecting ticks, but few animals recover from East Coast fever. Animals suffering therefrom do not show hæmoglobinuria. *Theileria mutans*, Theiler, 1907· Syn.: _Piroplasma mutans_. This is transmissible experimentally by blood inoculation. It occurs in cattle in South Africa and Madagascar and is apparently non-pathogenic. No Koch’s blue bodies are formed. It is transmitted by ticks. _Theileria annulata_ (Dschunkowsky and Luhs) occurs in cattle in Transcaucasia. A Theileria (_T. stordii_) has been found in a gazelle (França, 1912). Genus. *Anaplasma*, Theiler, 1910.