THE CELL ASTER 493 



cytoplasm between the paths of an exuded liquid flowing into the 

 sphere. The coming together of the egg- and sperm-nuclei 

 was observed to occur in the following manner: As long as the 

 egg-nucleus is beyond the confines of the aster, that is, while it 

 still lies in the liquid cytoplasm, it is stationary. When the 

 extending rays of the aster reach the egg-nucleus streaks of 

 gelatinizing cytoplasm appear all about it. The nucleus then 

 moves toward the sphere with increasing rate until, at the border 

 of the sphere, it works into the liquid area where it comes to lie 

 closely pressed against the sperm-nucleus. The movement of 

 the egg-nucleus may be explained by assuming that there exists 

 a centripetal current of the fluid in the rays. That such a cur- 

 rent exists may be inferred also from the following experiment: 

 In an egg one may occasionally see one or more small oil-like 

 droplets 2 to 4 micra in diameter. They are possibly due to 

 degenerative processes in the protoplasm. If one of these oil- 

 like droplets be pushed by the needle from the liquid cytoplasm 

 into the periphery of the aster it will move along the rays toward 

 the center. 



3. The amphiaster 



The large fusion nucleus occupies an excentric position in the 

 hyaline central area of the aster (fig. 7). The appearance of 

 being partially enveloped by the sphere liquid as by a cap is 

 enhanced by the gradual increase in size of the nucleus. Very 

 soon the ray-like structure of the cytoplasm begins to fade from 

 view (fig. 8). The disappearance of the rays commences in 

 what will be the equator of the dividing egg and gradually 

 extends to the two poles. That the disappearance of the rays 

 is due to a reversal of the gel to the sol state of the cytoplasm 

 is shown by the fact that the needle on being dragged through 

 the cytoplasm, now carries no distorted strands in its wake but 

 pushes the granules about as if they were embedded in a liquid 

 which was only slightly viscous. In the cases observed a few of 

 the rays extending from the tip's of the two poles in the plane of 

 the future longitudinal axis of the cell never faded entirely from 

 view. During this stage, which lasts a few seconds, the nucleus 



