THE BIOLOGY OF THE CELL SURFACE 



experimental evidence indicates that it is non-essential to 

 the living cell-substance. Secondly, the alveolar structure 





Fig. 2. — Two sections of the unfertilized egg of Nereis limbata (after Lillie). 

 a is badly fixed as shown by the partially dissolved yolk spheres and the wholly 

 dissolved oil drops which in h are intact. Compare b with the figure of the li\-ing 

 egg as shown in Fig. 22 (p. 158). v.m., vitelline membrane; c.l., ectoplasm. 



described for fixed cells, as it often has been, is the result 

 of improper fixation. In such cells the cytoplasm appears 

 a mesh, empty holes occupying the greatest space, holes 



60 



