OBSERVATIONS ON EUGLENA LEUCOPS, SP. NOV., A PARASITE OE STENOSTOMUM, WITH SPECIAL REFERENCE TO NUCLEAR DIVISION l S. R. HALL MILLER SCHOOL OF BIOLOGY, UNIVERSITY OF VIRGINIA INTRODUCTION A Stenostomum heavily infected with a colorless euglenoid parasite was found in a collection made near the University of Virginia. The morphology of this curious flagellate has led me to place it in the genus Euglena Ehrbg. My purpose is to describe this new form, its nuclear division and its relation to its host; discuss its systematic position; and record some further observations upon its life history. HISTORICAL Euglena-\ike parasites of rhabdocoels have been reported on previous occasions. Haswell (1892) reported from an undetermined species in Australia an intracellular, colorless flagellate that had neither stigma nor flagellum. In 1907 the same author reported from the same continent another colorless form, from a mesostomid. It possessed a stigma and when liberated from the host, it no longer progressed by metabolic or euglenoid movement but became somewhat bottle-shaped and swam spirally by a flagellum. This parasite was found not only inside the cells but also in the space between the gut and body wall. He did not attempt to identify either of these forms. In France, Beauchamp (1911) described Astasia captiva, a parasite within the " pseudocode " of Catenula lemna. His description is fairly complete. This form retained its flagellum in the host and bore a colorless "rudimentary" stigma. It measured 30 to 40 microns in length and even when liberated from the host moved only by a rapid metabolic (euglenoid) movement. He speaks of, and his figures show, the oblique surface striations and spoon-like depression near the posterior end of the body. He mentions the "conduit buccal" and nucleus as being typical of the "Eugleniens." 1 The writer is greatly indebted to Dr. B. D. Reynolds, under whose direction this investigation was carried out at the Miller School of Biology and the Mountain Lake Biological Station of the University of Virginia. 327
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