Ookinesis in ( Jorebratulus Lacteiis. 3G5 



the ceiitriole initiates the formation of both the centrosome and 

 ray-system. 



In a general way the size of the centrosome is proportional to 

 that of the cell in the same species, as has been pointed out by Boveri 

 ('01, p. 94) and Goldsehmidt ('02, pp. 400 and 424). The acconi- 

 jDanying diagram (Text Fig. A) shows this relation in Cerebratulus. 

 The sections of cells of various sizes (all at the uietaphase) were 

 taken at random, their diameters and the size of centrosomes were 

 measured, and were arranged in order. One notices at once 

 the proportional decrease in size of the controsomes as the cells 

 become smaller, while the centrioles remain without perceptible 

 change throughout. Furthermore it should be noted that in the cells 

 of pilidium the centrosome no longer exists. As the centroplasm is 

 present at any place of the cytojjlasm (as is seen in the normal fer- 

 tilization and in artificial production of cytasters) it is clear that 

 the larger the cell the more centroplasm, and consfcpiently ceteris 

 paribus, the centrosome can grow much more in larger cells than 

 in smaller ones. But the question why the large cells need large 

 centrosomes will remain unsolved until we come to know the 

 function of the latter. 



From what has been said it will be seen that the centrosome is 

 an ephemeral structure ]iroduced by the accumulation of centro- 

 jilasm around the centriole, and "nur von den Centriolen, nicht aher 

 von (lev Centvosomen, l-ana daliev gelten, dass sie allgemeine und 

 dauernde Zellorcjane siud," as has been maintained by Meves ('02, a 

 and h) ; Bouin ('04) and the Schreiners ('06, p. 448). Although 

 Boveri hinted at this conclusion as a mere possibility ('01, p. 185), 

 he seems to lay more stress on the centrosome than the centriole.^ 

 ^Nevertheless the centrosome theory does not lose its validity for the 

 reason that the centriole physiologically represents what was called 

 centrosome when the theory was first formulated. 



In her excellent paper on Enteroxenos ('06) Bonnevie advances 



"Vejdovsky's and MrAzek's ground of denying Boveri's idea of continuity 

 of the centrosome is soniewliat different from tlie above authors, they emplia- 

 sizing more the rwir formnlinn of a new centrosome in tlie old, than its peri- 

 oiVioal coinplctc disappearance ('03, p. 555). 



