252 SOME ASPECTS OF CELL-CHEMISTRY AND CELL-PHYSIOLOGY 



that the same is true of Zygnema and (Edigonium. By plasmolysis 

 the cells of these forms may be broken up into fragments, both 

 nucleated and non-nucleated. The former surround themselves with 

 a new wall, grow, and develop into complete plants ; the latter, while 

 able to form starch by means of the chlorophyll they contain, are 

 incapable of utilizing it, and are devoid of the power of forming a 

 new membrane, and of growth and regeneration. 1 



Although Verworn's results confirm and extend the earlier work of 

 Nussbaum and Gruber, he has drawn from them a somewhat different 

 conclusion, based mainly on the fact, determined by him, that a 

 nucleus deprived of cytoplasm is as devoid of the power to regenerate 

 the whole as an enucleated mass of cytoplasm. From this he argues, 

 with perfect justice, that the formative energy cannot properly be 

 ascribed to the nucleus alone, but is rather a co-ordinate activity of 

 both nucleus and cytoplasm. No one will dispute this conclusion ; 

 yet in the light of other evidence it is, I think, stated in somewhat 

 misleading terms which obscure the significance of Verworn's own 

 beautiful experiments. It is undoubtedly true that the cell, like any 

 other living organism, acts as a whole, and that the integrity of all of 

 its parts is necessary to its continued existence ; but this no more pre- 

 cludes a specialization and localization of function in the cell than in 

 the higher organism. The experiments certainly do not prove that 

 the nucleus is the sole instrument of organic synthesis, but they no 

 less certainly indicate its especial importance in this process. The 

 sperm-nucleus is unable to develop its latent capacities without be- 

 coming associated with the cytoplasm of an ovum, but its significance 

 as the bearer of the paternal heritage is not thereby lessened one iota. 



2. Position and Movements of the Nucleus 



Many observers have approached the same problem from a dif- 

 ferent direction by considering the position, movements, and changes 

 of form in the nucleus with regard to the formative activities in 

 the cytoplasm. To review these researches in full would be impos- 

 sible, and we must be content to consider only the well-known 

 researches of Haberlandt ('77) and Korschelt ('89), both of whom 

 have given extensive reviews of the entire subject in this regard. 

 Haberlandt's studies related to the position of the nucleus in plant- 

 cells with especial regard to the growth of the cellulose membrane. 

 He determined the very significant fact that local growth of the 

 cell-wall is always preceded by a movement of the nucleus to the 



1 Palla ('90) has disputed this result, maintaining that enucleated masses of protoplasm 

 pressed out from pollen-tubes might surround themselves with membranes and grow out 

 into long tubes. Later observations, however, by Acqua ('91), throw doubt on Palla's 

 conclusion. 



