Observations on the Morphology and Division of Eudiplodinium neglectum Dogiel (Ciliata Entodiniomorpha) from the Stomach of a Moose (Alces americana).*

Abstract

SUMMARY. The material containing the ciliate Eudiplodinium neglectum Dog. from the rumen of a moose was fixed with 4% formalin solution and studied both unstained and after staining with methylene blue or methyl green.This ciliate is closely related to Eudiplodinium neglectum Dog. (1925) formae spectabile Dog. (1925) and impalae Dog. (1925), but differs from them in the presence of a transverse cuticular line. The form of the macronucleus of the investigated ciliates is regularly elongated clavate, the anterior end being wider than the posterior one. The following measurements were obtained from 14 specimens: length 81.3 μ (67.2–112 μ), width 66.2 μ (48.8–84 μ).During division the anterior daughter gets the old skeletal plate and a new one arises de novo in the posterior daughter. The anlage of a new skeletal plate for the posterior daughter was observed in earlier and later telophases, first as an indistinct structure, later as a group of a variable number of granules, more often about 30. This anlage gradually grew into a typical skeletal plate. The anlage of the pharynx in the posterior daughter was seen in later telophases. A part of the distal end of the old skeletal plate (one, two or five rectangular prisms belonging to this organelle) and a part of the distal end of the old oesophagus are possibly cut off during division and dissolved in the protoplasm of the posterior daughter. A crossing of the distal end of the old skeletal plate by the division plane was observed only in those specimens in which this part consisted of one row of the rectangular skeletal prisms and was not found in the specimens with a shaft of the skeletal plate consisting of two rows of polygons. In later division stages a bending of the old skeletal plate takes place.The morphological plasticity of the skeletal plate (loss of the distal part and subsequent bending of this organelle during the division of the ciliate) observed by the present writer and its dynamic reversibility (disappearing during starvation and thickening under satisfactory feeding conditions, reported by Westphal) confirm the assumption that the skeletal lamina functions primarily as a storage organelle. Some cases of destruction and defective development of the old skeletal plate were observed.The presence of fat in some specimens of E. neglectum Dog. is noted.