136 The Unitij of the Organism 



nuclear membrane. . . . For these and other reasons the 

 terms 'nucleus' and 'cell-hodij' should probably be regarded 

 as only topographical expressions denoting two differen- 

 tiated areas in a common structural basis. The terms kary- 

 oplasm and cytoplasm possess, however, a specific signif- 

 icance owing to the fact that there is on the whole a definite 

 chemical contrast between the nuclear substance and that of 

 the cell-body. . . . 



"Both morphologically and physiologically the differen- 

 tiation of tlie active cell-substance into nucleus and cell-body 

 must be regarded as a fundamental character of the cell 

 because of its universal . . . occurrence, and because there 

 is reason to believe that it is in some manner an expression 

 of the dual aspect of the fundamental process of metabolism, 

 constinictive and destructive, that lies at the basis of cell 

 life." -2 



So far as I am able to make out, authorities are in essen- 

 tial agreement as concerns the directly observational part 

 of this statement touching the relation between nucleus and 

 cell-body. The general conclusion is that, keeping an eye 

 on the actual structure of the cell and ignoring for the 

 moment the system of naming applied to the different parts, 

 Schultze and Strasburger were both right ; Schultze in hold- 

 ing that there is something fundamental in the distinction 

 between nucleus and cell-body, and Strasburger in holding 

 that there is something fundamental in the kinship between 

 the two. Interpretatively, therefore, the question resolves 

 itself into one of naming and classifying what is observed, 

 and there can be no doubt, as Wilson and a majority of 

 recent authors have recognized, not only of the convenience 

 but of the scientific soundness of using the term plasm for 

 the living substance of the cell as a whole, and then des- 

 ignating the kindred but yet different kinds of plasm by 

 the terms karyoplasm and cytoplasm. 



