MUSEUM OF COMPARATIVE ZOOLOGY. 533 



of the external half of the archiamphiaster becomes fused with the en- 

 velope of the polar globule at its distal pole. Whether the correspond- 

 ing corpuscles of the deep aster are also excluded from participating in 

 the formation of the new nucleus is more doubtful, but certain appear- 

 ances (Figs. 58, 60) favor the view that they may persist as discrete 

 bodies for a long time, perhaps till the new nucleus has acquired a mem- 

 brane. In that event they could hardly be employed in the nuclear 

 reconstruction without losing their morphological identity. As the area 

 more often appears homogeneous during the later stages of nuclear 

 growth (Figs. 59, 68, 93, 91) it is reasonable to assume that they are 

 ultimately redissolved. 



There is one point in connection with the genesis of the asters accom- 

 panying the first segmentation which deserves particular attention. If 

 it could be shown that the rays of the "conjugation aster" are gradu- 

 ally altered in direction so that a portion became centred about one of 

 the poles of the first segmentation spindle, and the remainder about the 

 opposite pole, it would be strong evidence in favor of Hertwig's view 

 that the radial phenomena are due to the attractive force exerted by the 

 nucleus upon the protoplasm, and that these forces, at first operating 

 uniformly in all directions, distribute themselves with the elongation of 

 the nucleus to its two poles. But the proof is not yet convincing ; on 

 the contrary, it appears as though the asters at segmentation arise quite 

 independently of the "conjugation radiation." The evidence that these 

 asters are due to the direct attraction of nuclear substance appears ma- 

 terially weakened by this want of continuity in their manifestations. 

 While I concur with Hertwig in the belief that there is an attractive 

 force exerted upon the vitelline protoplasm, which emanates from the 

 centre of the radiation, I would suggest that the force is generated by 

 the fusion of two unlike substances, — one of which is vitelline proto- 

 plasm, the other probably fluid constituents of the nucleus, — and not 

 by the attractive properties of either. Thus the attraction on the one 

 hand of protoplasm from the vitellus, and on the other of nuclear matter 

 from the nucleus (migration of lateral zones), may be effected by the same 

 force. But if it is nuclear substance alone which exerts the attractive in- 

 fluence, how shall it be explained that it attracts the nuclear disks ^ 



Spiral Asters. — I have designated as spiral asters certain peculiar 

 conditions often affecting the stellate figures connected with the elimina- 

 tion of polar globules. I have not met with anything in the observa- 

 tions of others which can be classed with these appearances. The rays 



