THE BIOLOGY OF THE CELL SURFACE 



are set off as two distinct regions, as a sphere (nucleus) 

 within a sphere (cytoplasm), this sharp differentiation is 

 not invariable. For several reasons, as will be shown 

 beyond, much of modern biological investigation has 

 centered upon the nuclear component as though it were 

 indeed the kernel of life. Not only has the cytoplasmic 

 component been relatively neglected but also have those 

 protoplasmic systems which lack sharply defined and set- 

 off nuclei received scant attention, although a bacterium 

 whose protoplasmic organization fails to show a discrete 

 nucleus is a living system. Because of the rapid rise of 

 genetics, hegemony in the protoplasmic organization has 

 been ascribed to the chromosomal structure of the nucleus 

 and the cytoplasm has been subordinated as though it be a 

 mere protective and nutritive shell. It is no part of the 

 purpose of this book to minimize the achievements of 

 genetics and the investigations on chromosome-structure, 

 all outgrowths of descriptive studies on protoplasmic 

 organization. Instead, inasmuch as life, as we know it so 

 far, resides in the whole system, the pages which follow 

 aim to show how far life-processes are related to the dual 

 and reciprocal components, nuclear and cytoplasmic 

 structure. 



Investigations on cytoplasm have had largely to do with 

 the formed bodies, the so-called cytoplasmic inclusions; 

 only to a very small degree have they dealt with the cyto- 

 plasm itself and its differentiation into an inner and an 

 outer region, endoplasm and ectoplasm. Only in a general 

 way has the role of the ectoplasm, the surface cytoplasm, 

 been hinted at; thoroughgoing descriptions of it, compar- 

 able to those of the nucleus, have not been made, doubtless 

 because of the greater difficulties of observing it. None 

 the less should the ectoplasm, as part of the protoplasmic 

 system, be assigned a role in vital manifestations. An 

 examination of its properties and behavior in life-processes 



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