112 FRANK R. LILLIE. 



experiments, it becomes a conclusive argument for the re-forma- 

 tion of rays in successive positions of the spindle, a condition that 

 can be explained only on the centrosome hypothesis. 



Among the numerous cases we find some in which the anti- 

 polar rays are very slightly developed at both ends ; and various 

 intergrading conditions that seem to indicate stages in the forma- 

 tion of new rays. 



In the case of eggs submitted to low centrifugal force an 

 occasional karyokinetic figure is found with distorted astral rays. 

 But such a condition must occur as a transition stage in every 

 case of spindle movement on the centrosome hypothesis, because 

 of the mere viscosity of the medium and the inertia of the oriented 

 particles. The occurrence of such conditions is therefore to be 

 expected, and does not furnish any argument against the center 

 of force hypothesis. 



2. MOVEMENTS OF GRANULES INTO THE AREA OF THE KARYO- 

 KINETIC FIGURE. 



The three classes of granules, basophile, acidophile, and fat, 

 may be moved into the area of the karyokinetic figure. As a 

 general proposition we may say that fatty or acidophile granules 

 driven into the area of an aster tend to destroy the radiations and 

 are not themselves arranged in lines. If forced into the spindle 

 itself, they tend to disarrange its fibers. On the other hand, 

 basophile granules that are driven into the area of the asters or 

 spindle do not, apparently, destroy the existing rays or fibers, 

 and are themselves arranged conformably to the lines of the 

 figure. 



A. We need not dwell long on the statement concerning fatty 

 and acidophile granules. It is sufficiently supported by Figs. 

 5 and 6 as regards the asters. No traces of rays "are left in in- 

 vaded areas of the asters except that the scanty basophile gran- 

 ules between the fatty or acidophile granules may show a slight 

 radiate tendency centered at the poles of the spindle. There are 

 no detached rays, no traces of broken down threads ; the periph- 

 eral ends of rays of invaded areas always disappear absolutely. 



Serious disarrangement of the fibers of the spindle is found if 

 fatty or acidophile granules are driven into it. Such cases are 



