LEUCOCYTOZOON DANILEWSKYI 



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the biting of the owl by Culex pipiens L., and the sucking of blood containing 

 micro- and macro-gametocytes. 



Microgametoeyte.— The microgametocyte may attain dimensions much 

 larger than a leucocyte, and exists in the blood of the owl in two conditions : 

 (i) a free active stage in the liquor sanguinis; (2) endocellular resting stage in a 

 blood cell ; and, later, when the parasite has become too large to penetrate a host 

 cell, free in the blood stream. In this condition the parasite may engulf the 

 cells which formerly served it for food and shelter. 



(i) Free Active Stage. — This is the trypanosome stage (7". ziemanni). The 

 anterior end is sharp -pointed, with a kinetonucleus just at its base, from 

 which the flagellum arises, passing posteriorly along the body and projecting 

 some distance from the posterior end. There is a well-defined undulating 

 membrane, with sixteen myonemes arranged in four double rows or pairs on 

 each side. The trophonucleus is well developed, and situate near the centre 

 of the trypanosome. 



Fig. 121. — Leucocytozoon danilewskyi 

 Ziemann: Microgamete. 

 (After Schaudinn.) 



Fig. 122. — Leucocytozoon dani- 

 lewskyi Ziemann : Macro- 

 gamete, 



(After Schaudinn.) 



Fig. 123. — Leucocytozoon danilewskyi Ziemann: The Development of the 

 Ookinete and the Formation of Small Trypaniform Bodies. 

 (After Schaudinn.) 



(2) Endocellular Resting Stage. — In the intracellular stage the parasite is 

 quite spindle-shaped, the ends being composed of ectoplasm, while the 

 endoplasm forms a dark oval central mass containing the trophonucleus, close 

 to which the kinetonucleus is situated. The flagellum has disappeared, but 

 the myonemes of the ectoplasm can still be seen. 



Macrogametoeyte. — This has also two stages — (i) free, (2) endocellular. 



(1) Free Active Stage. — The free stage differs from the microgametocyte in 

 being larger, in having no free projection of the flagellum, and in having 

 smaller tropho- and kineto-nuclei, and in the myonemes not being arranged 

 in pairs. 



(2) Resting Stage. — This differs from the microgametocyte in being large, 

 with smaller nuclei. 



These gametocytes, called ' leucocytozoon ' by Danilewsky and ' hcem- 

 amoeba ' by Laveran, being found in the peripheral blood of the owl, are sucked 

 into the stomach of Culex pipiens, and then proceed to conjugation. 



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