244 C. O. WHITMAX. 



5. Thirty to forty minutes after deposit a well marked con- 

 striction passes like a peristaltic movement from the middle of 

 the egg towards the oral pole, at the conclusion of which the 

 first polar glohule arises from a pellucid spot in the centre of 

 the stellate figure. Thirty minutes later the second polar 

 globule takes its exit from the same place, attended by a much 

 weaker constriction than the first. 



6. After the ])roduftion of the two nearly equal polar globules, 

 the remains of the archiauiphiaster are converted into \\\^ female 

 jjronuclcus, in which a pair of nucleoli ap[)ear a little later; and 

 at about the same time the male pronuclens} containing one 

 nucleolus, appears not far from the opposite pole. 



7. Fifteen minutes after the elimination of the ])olar globules 

 a ring-like depression, or constriction, appears in the yolk around 

 the oral pole, and in this depression a transj)arent, liquid sub- 

 stance (nuclear ?) is collected, forming the first polar ring. 



8. Eive or ten minutes later pseudopode-like extensions of 

 the ring-substance (ring-rays) are formed on the equatorial side 

 of the ring. The same phenomena repeat themselves a little 

 later on the aboral pole. 



9. The ring-rays, having attained a maximum intensity, 

 gradually disaj)pear as the rings concentrate to form two 

 discs, one of which covers the aboral pole, while the other is 

 pierced through the centre by a slender column of yolk, which 

 has a calotte-like summit. 



10. Before the first cleavage both discs plunge deep into the 

 egg, and possibly contribute some elements to the nucleus, which 

 may either induce or stimidale the molecular changes, which 

 result in the formation of the primary cleavage amphinster. 



11. At the approach of the cleavage, the aboral disc is visible 

 only as a mere point if seen from the surface, while the oral 

 disc has taken the form of a semi-lunar spot ; and at the com- 

 pletion of the same, the remnant of both discs is found in the 

 larger of the two cleavage-s[)h('res. 



12. The two pronuclei, whose longest diameters are parallel to 

 the axis of the ^'d,^!,, approach and coalesce to form the primary 

 cleavage nucleus, the longer axis of which is soon found at 

 right angles to the axis of the egg. 



13. The j)ronucleoli meet in the centre of the so-formed nu- 

 cleus, increase a little in size, and maintain their individuality 

 till the first cleavage-amphiaster begins to form, then dissolve. 



II. In each pole of this amphiaster a central area arises, 

 which colors less with carmine than the surrounding nucleo- 

 plasm, and in tli(; edge of which the convergit)g rays end. These 

 areas take the form of striated stripes after the disappearance of 

 ' fcifc iioli', p. 2155. 



