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Artefacts from Blood Smears

Monocercomonoides and Chilomastix

Monocercomonoides and Chilomastix.

During October, 1947, 137 sheep (Ovis aries L.) were examined at the Wellington City Corporation abattoirs. In the majority of cases, smears were made directly from the hearts of freshly slaughtered animals, but a meat inspector who was assisting me made a number of preparations from blood dripping from the necks of hung and gutted carcases. Several of these latter smears proved to contain numerous flagellates referable to the genera Monocercomonoides and Chilomastix. These protozoans commonly form part of the fauna of the lower intestine of various animals. Having gained access to the blood when the posterior end of the rectum was severed, they must have been carried down to the neck when the carcases were hung up. Intestinal protozoa are best prepared for study by wet fixation, followed by staining utilizing one of the "never-dried" techniques. As the material in question was intended for the study of haematozoa, the smears were air-dried, fixed in methyl alcohol, and stained with Giemsa. Consequently, the flagellates are so poorly fixed and stained that little more than their generic features can be made out. All the examples of Monocercomonoides are too badly hypertrophied for measurement, and nuclear detail cannot be distinguished. Four flagella originate in pairs from two blepharoplasts, which are situated in front of the nucleus and connected to each other by a rhizoplast. From one of the blepharoplasts. a fine axostyle runs back to the posterior end of the body. The Chilomastix has an ovoidal body, averaging 8μ by 6μ, and tapering sharply posteriorly to a slender caudal process some 5μ in length. The cytostome lies in the anterior two-fifths of the body, and a few examples seen contain ingested bacteria. Three subequal anterior flagella are present, the length of these being somewhat less than that of the body.

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Apart from the presence in them of flagellates, the smears bear remarkably little evidence of contamination, considering their origin. This provides an excellent example of the dangers attendant upon describing material from preparations collected by others, without full knowledge of the circumstances of collection. Other investigators have recorded various intestinal flagellates as contaminants in blood. Martoglio (1917) went so far as to establish a new genus, Haematrichomonas, for trichomonads from this source. Wenyon (1926) and Cooper and Gulati (1928) have summarized the references dealing with trichomonads in blood smears. There are no grounds for accepting any of the cases recorded as other than examples of the adventitious invasion of the circulatory system by intestinal flagellates.