Abstract
(Ward, 1927, 1929), and in connection with another investigation I was making (Essex, 1927), a large number of copepods from Long Lake, Ely, Minnesota, were examined for larval tapeworms. Magath first called my attention to an interesting procercoid in the body cavity of Diaptomus oregonensis. This parasite was subsequently seen in two other copepods of this species. When liberated from the body cavity of the host the parasite was markedly quiescent as compared to the great activity exhibited by the larvae of certain other species which I have observed. An examination of the larvae revealed that they were composed of two distinct body regions, the body proper and an exceedingly long caudal appendage or cercomer. The body portion which measured 0.23 by 0.13 mm., was ovate, and the anterior margin in the terminal region turned in toward the middle where a set of hooks could be distinguished (Figs. a and b). In the living specimen only four hooks could be seen distinctly, but after the organism had been allowed to disintegrate slightly eight hooks could be clearly seen (Fig. c). The hooks, which measured about 110/ in length and about 22M in their broadest portion, were arranged roughly in four pairs. Acetabula were not observed. Scattered throughout the body portion were many refractile bodies of varying size and shape. Such bodies were not seen in the cercomer. This part of the organism measured about 1.8 mm. in length with an average diameter of about 0.03 mm. The terminal portion was somewhat broadened and bore the six cast-off hooks of the oncosphere.
Published Version
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