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FIG. 5. A and Β : Cortical particles of Spatangus purpureas. Inner arrows, lamella
with "holes"; exterior arrows, shanks connected with membrane of particle; double
nature of membrane well visible. X 55,000. (Afzelius.)
across the hole. In the mass of the lamella, vacoules with vague outlines
were distinguishable (diameter around 200 Â ) . Their fusion m a y give
rise to larger vacuoles which appear as the holes.