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THE AMERICAN NATURALIST [Vol. XLIV 



evidence of unmistakable differentiation. I do not allude 

 to the alleged hereditary substance, ehondrosomes, to be 

 mentioned beyond, but merely to such differentiation as 

 spindle fibers, which in many higher plants are almost 

 wholly of cytoplasmic origin. As is well known, Stras- 

 burger has endeavored to make things clearer by apply- 

 ing to such parts of the cytoplasm as spindle fibers cen- 

 trosomes, centrospheres and the plasma membrane of 

 the cell, the term kinoplasm, attributing to this substance 

 certain activities. The researches of Noll upon marine 

 alga? indicate with a very high degree of probability that 

 the plasma membrane is the part of the protoplasm which 

 takes a leading part in responding to external stimuli. 

 The doctrine that an enucleated cell can not do any con- 

 structive work, as, for example, forming a cellulose wall, 

 has become so generally accepted that the same has 

 found its way into general reference works. This doc- 

 trine has in recent years been disputed, but so far as I 

 am aware it has not been satisfactorily disproved. I 

 shall not bring into this category such cytoplasmic dif- 

 ferentiations as chloroplasts and other plastids, but 

 enough has been said to indicate that the cytoplasm as 

 well as the nucleus is a differentiated body, which means 

 a diversity of functions or activities. Now, although 

 cytoplasm and nucleus have certain functions that seem 

 in a large measure independent, yet the interrelation of 

 these two parts of the cell is such that neither can exist 

 and function to any great extent without the other. No 

 one has up to the present time been able to isolate a 

 nucleus and keep it alive any length of time apart from 

 living cytoplasm. Whatever the nucleus does, it must 

 do in connection with living cytoplasm. The cytoplasm 

 is in a sense the special environment of the nucleus, and 

 it is in this environment that the nucleus must exist and 



so intimately connected with the nucleus that even a 

 momentary separation may prove fatal, for the skill of 



