96 GARDINER. [Vol. XV. 



As the centrospheres draw apart, the nuclei break to pieces 

 and the whole substance, except what is contained in the 

 clumps, is scattered throughout the cytoplasm, which in con- 

 sequence stains much more deeply for a time. Meantime, 

 when this spindle has about attained its full size the rods of 

 chromatin do not continue to elongate, but on the contrary flow 

 together at about their middle points, thus forming a continuous 

 ring which lies in exactly the position afterwards occupied by 

 the equatorial plate. This ring even while forming has numer- 

 ous outward prolongations extending into the surrounding cyto- 

 plasm (Figs. 28 and 30). Sections showing this structure were 

 very carefully studied, for nothing similar to it has to my 

 knowledge been described in amphiaster formation. To guard 

 against the possibility that this structure might be an artifact, 

 ova killed in Hermann's, corrosive, corrosive acetic, Flem- 

 ming's, formaline, and picro formaline, were sectioned, and the 

 structure as here figured was found in ova killed with all these 

 different reagents ; therefore it can be stated with confidence 

 that it occurs normally in the formation of the amphiaster in 

 this egg. As is shown in Fig. 28, the prolongations, or 

 equatorial rays as they m.ight be called, are composed for the 

 most part of separate granules of chromatin, while the chro- 

 matin which occupies the position of the future chromosomes 

 is much more compact. This difference I believe to be due 

 to the absorbing action of the cytoplasm on these exposed rays. 

 It may indicate that as the granules aggregate to form the 

 chromosomes, the surplus material flows away in the form of 

 these equatorial rays. The number of rays is apparently the 

 same as the number of chromosomes. At a little older stage, 

 sections through the equatorial plate (Fig. 34) show thirty-one 

 cheveron-shaped chromosomes, from the bases of which numer- 

 ous dark anastomosing lines radiate outward. These appar- 

 ently are in a measure the remnants of the chromatin pro- 

 longations and the whole area tinges somewhat more deeply 

 than the rest of the cytoplasm, exactly as is shown in Fig. 14, 

 when chromatin is dissolved by the cytoplasm. Later the 

 cheveron-shaped chromosomes break at the apexes to split into 

 two. 



