THE BIOLOGY OF THE CELL SURFACE 



forth, that the external covering of a cell is similar to or 

 identical with such intracellular partitions. 



The understanding of the cell-surface and of the capaci- 

 ties residing in the ground-substance is forwarded by 

 appreciation of that component of the protoplasmic system, 

 which I now discuss in detail: The ectoplasm. 



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