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Quarterly Journal of Microscopical Science, Vol s2-82, 311-326, Copyright © 1940 by Company of Biologists

Memoirs: On the Anatomy of Cerearia Macrocerca from Spliaerium Corneum

G. G. VICKERS M.Sc.1

1 Department of Zoology, University of Manchester

A detailed anatomical description is given of the sporocyst and cercaria of Cercaria macrocerca (Fil.) from the gills of Sphaerium corneum (Linn.).

The development of the large cells surrounding the excretory vesicle of the cercaria is described. It has been found that the granules with which these cells are packed originate round the nucleus and afterwards migrate towards the lumen of the vesicle. These granules do not appear to be discharged on encystment of the cercaria to act as cystogenous material; they are shed gradually into the excretory vesicle, and it is therefore natural to suppose that they are granules of excretory material.

In heavy infestations the mechanical effect of large numbers of sporocysts between the gill lamellae of the host completely prevents reproduction of the mollusc. Cercariae escaping from the sporocysts continually rupture the gill lamellae of the host, and large areas of the gills are thus put out of action.






© The Company of Biologists Ltd 1940