April, 1922.] KOMURO .—PRELIMINARY NOTE ON THE CELLS 43 



I am inclined to think that changes, such as enlargement of 

 both the cell and the nucleus, vacuolization of both the nucleolus 

 and the cytoplasm, increase of the number of nucleolus, and decrease 

 of chromatic substance, mean senescence and in addition to the 

 above changes karyolytic and pyknotic conditions may be with a 

 high degree of probability taken as outward expressions of approach- 

 ing the end of cell-life. 



Formation of Multinucleated Cells. 



It is noteworthy that both binucleated and multinucleated cells 1} 

 are found in the tissue of radicles from irradiated seeds together 

 with many degenerative changes described in the previous section. 

 In the control, on the contrary, I have seen neither binucleated or 

 multinucleated cells supposed to be caused by degenerative processes, 

 although some cells in the plerom tissue are found normally in a 

 binucleated condition. 



A) Binucleated cells in our material seem to have been produced 

 in one of the following ways in combination with the suppression of 

 cell- wall formation : 



1) equal and unequal division of nucleus by an amitosis- 

 like process. 



2) asymmetrical mitoses. 



3) fission of the nucleus in two during a prophase of 

 mitosis. 



B) Multinucleated cells may be the results of one of the follow- 

 ing ways in combination with the suppression of cell-wall formation : 



1) multipolar mitoses. 



2) irregular distribution of chromosomes during mitosis. 



3) similar processes described under A taken place in 

 mononucleated or binucleated condition. 



I presume that formation of multinucleated cells is in part due 

 to lessened vitality (senescence) on the part of cytoplasm, that is, 

 failure of the growth of cytoplasm including cell-wall material for 

 normal divisions. 



In plant tissues we cannot take multinucleated condition if occur 

 singly as an absolute sign of degeneration, but if this condition 

 comes in combination with karyolysis and pyknosis, then it may 

 safely be concluded that this is an outward expression of degeneration. 



1) By multinucleated cells those containing more than two nuclei are meant. 



