CELLULAR ORGANIZATION OF LI\'L\G .^L^'rTKR 17 



complete, at least in the sense that both nucleus and 

 cytoplasm (or portions of both) are present. This is 

 shown by experiments on enucleated cells, such as egg 

 cells; portions containing nuclei survive; the others 

 die. But if enucleated portions are fertilized and thus 

 furnished with nuclei, they continue to live.' An other- 

 wise complete protozoon such as Stcntor will die if 

 deprived of its nucleus, while fragments of less than 

 one- twentieth the normal size will survive and reform 

 a complete organism if a portion of nucleus is present. "^ 

 Similar results have been obtained in experiments on 

 other protozoa; e.g., Verworn's with ThalassicoUa.^ 



There is a large body of similar experimental fact 

 indicating that the continued interaction of nuclear and 

 cytoplasmic components is an essential feature of nonnal 

 cell-metabolism. It is usually supposed that the nucleus 

 has special relations to synthetic metaboUsm; hence 

 its special importance in growth and regeneration, but 

 the whole problem of the relation of nucleus to cytoplasm 

 is at present in an unsatisfactory state."* 



It is clear, nevertheless, that the nucleated cell of the 

 higher organism is a complete and autonomous living 

 unit. But in view of what has just been pointed out 

 regarding the non-cellular or subcellular constitution of 

 some organisms, we must avoid regarding the dis- 

 tinctively cellular features of protoplasmic organization 



» Cf. Delage, Arch, de zool. cxp. el ghi., VII (1899), 383. 



=« F. R. Lillie, Journal of Morphology, XII (1896), 239. 



aVerworn, Arch. ges. Physiol., LI (1891); cf. also Allgcmcme 

 Physiologic, 5th edition (1909), p. 620. 



4 For a recent study cf. V. Lynch, American Journal of Physiology, 

 XLVIII (1919), 258. 



