HOMOLOGY OF THE CENTROSOME. 



S. WATASE. 



Naturalists are now pretty well agreed that the lately 

 discovered centrosome with its sphere represents a highly 

 important constituent of the cell, and that it is to be placed in 

 the category of permanent cell-organs, as the nucleus and the 

 cytoplasm. Indeed one^ of the foremost cytologists has 

 recently said that the discovery of the centrosome marks as 

 important an era in the history of biological science as did the 

 discovery of the cell-nucleus itself. 



Those who have paid any attention to the subject will hardly 

 question the physiological importance of the centrosome. But 

 the view that the centrosome with its sphere is an organ equal 

 in morphological importance and as permanent as the nucleus, 

 is open to serious criticism. For the claim of the absolute 

 novelty and the unique character of the centrosome is, after 

 all, based on the assumption, tJiat among the hitherto recognized 

 elements in the cell, there is nothing comparable to the centro- 

 some, either in function or in structure. 



If there is any known element in the cell which can be 

 shown to have a close affinity to, or identity with, the centro- 

 some, its claim as a unique morphological organ in the cell 

 must fall to the ground. 



Investigators who have studied this subject have generally 

 selected cells in which the centrosome appeared in a most con- 

 spicuous form ; and naturally, as the main object at first was 

 to demonstrate its existence. But the possibility of discovering 

 the homology of the centrosome among the other cell-constit- 

 uents, if such exist, is rendered all the more difficult, as long 

 as our attention is directed only to those cells in which the 

 centrosome has reached its highest development. 



Among the number of animal and vegetable cells I have 

 studied, a most instructive illustration of this fact is afforded 



1 W. Flemming : Ueber Zellteilting. Verhandl. d. Anat. Gesellschaft zu Miinchen, 

 1891. 



