THE ROLE OF THE NUCLEUS IN THE CELL 

 FUNCTIONS OF AMCEEJE. 



ELERY R. BECKER. 



From the Dept. of Biology, Princeton University, and the Dept. of Zoology 

 and Entomology, Iowa State College. 



The importance of the cell nucleus in chemical synthesis of 

 cell elements, regeneration, cell division, fertilization, and 

 heredity is now appreciated. There are, however, many prob- 

 lems connected with role of the nucleus in the ordinary, everyday 

 life of the cell which have not been so fully worked out. To 

 many of these problems the metazoan cell forbids an approach 

 because it is too differentiated, too specialized. In addition, it is 

 difficult to eliminate the factor of interrelationship of cells in 

 making such studies on the role of the nucleus. For this and 

 other reasons the protozoa have supplied favorite objects for 

 such studies. Because they lead a more or less autonomous 

 existence they exhibit their vitality in a greater diversity of 

 activities than do metazoan cells. 



The researches of Gruber, Balbiani, Verworn, Morgan, Hofer, 

 Stole and many others have supplied ample evidence that an 

 enucleated protozoan is incapable of regenerating any lost cell 

 structure; e.g., Morgan found that as much as 1/64 of a protozoan, 

 Stentor, will produce a new individual if it contains a nucleus, 

 but not if one is absent. The non-nucleated part will heal the 

 wound, but will not regenerate lost cell organelles. Verworn too 

 found that if he bisected a Foraminiferan, Polystomella, the part 

 without the nucleus would not regenerate the material for a new 

 shell as the nucleated portion did. An apparent exception is the 

 contractile vacuole of amoebae which, it is generally agreed, 

 always appears anew in an enucleated fragment of an amoeba 

 not possessing one at the time of merotomy. 



In ciliates generally locomotion is not affected by removal of 

 the nucleus. There are, however, certain factors bearing upon 

 the locomotion, irritability and nutrition of the cell, especially in 

 the amoebae, concerning which there is much disagreement. 



The method generally used in studying the bearing of the nucleus 



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