ABSTRACT
The stratification of various cell organelles and of important chemical substances have been studied in the eggs of the slug, after moderate centrifugation.
As in other molluscs the egg contents stratify typically into three well-defined zones - lipid, hyaline and yolky zones - but a distinct equatorial band of inclusions consisting mainly of phagosomes and associated lysosomes was detected in the most centrifugal region of the hyaline zone.
The sub-stratification of various cell inclusions in their respective zones was determined in some detail.
The role of the cell membrane and egg cortex in the redistribution of these inclusions and the nature of the ergastoplasm are discussed in the light of electron-microscope studies of eggs of this slug and of the sea urchin.
