90 GARDINER. [Vol. XV. 



ruptured just before the worm containing ttiem was placed in 

 Hermann's fluid. The cytoplasm had flowed or been pressed 

 out of the ovum carrying with it the amphiaster. In both 

 cases the cytoplasmic network had been completely bent and 

 twisted into a confused snarl. The achromatic rays were some- 

 what, but not nearly so much, distorted, but the centrospheres 

 were almost unchanged. From this I infer that the amphiaster 

 and the rays are on the whole much more rigid than the cyto- 

 plasmic network or the cytoplasm from which they were formed. 



As one end of the amphiaster approaches the wall of the 

 ovum the network is brought in contact with it, and as the 

 amphiaster continues to approach, the network intervening dis- 

 appears, being absorbed into the cytoplasm, although round 

 the other aster the network continues as distinct as ever 

 (Fig. i6). At no time does the network extend far into the 

 cytoplasm, only the immediate neighborhood of the spindle being 

 involved. The rest of the cytoplasm looks in no way different 

 from that of an ovum in which the nucleus is still intact. 



Shortly after the amphiaster has broken away from the 

 remnant of the nucleus the centrospheres increase enormously 

 in size, having a fairly reticular structure, merging gradually 

 on the one hand into the chromatic rays which connect it with 

 the cytoplasmic network, and on the other hand with the achro- 

 matic spindle fibers. Before the amphiaster is fully formed, 

 indeed at about the time the linin of the nucleus is beginning 

 to flow out (Fig. 12), an exceedingly small centrosome appears 

 for the first time in each centrosphere, and as these structures 

 enlarge the centrosomes become more conspicuous. By the 

 time the amphiaster breaks away from the nucleus (Fig. 14), 

 the centrosomes have become very prominent. In the stage 

 shown in Fig. 22 I have been able to discern a small central 

 black body within a small vesicle which stains a light blue. 

 This, however, is difficult to demonstrate, for in order to dis- 

 tinguish these structures the stain must be of exactly the right 

 intensity. The number of sections which show this stage is 

 comparatively small, and, many of them have been ruined — 

 after being studied — • in removing the cover slip and experi- 

 menting for the exact amount of stain necessary. I have not 



