202 BULLETIN OF THE 



Does the spindle completely disappear ? Or does the vitelline half 

 persist 1 And if it remains, does its outer end become the centre of 

 a new force, acting on the surrounding protoplasm to induce a new pe- 

 ripheral star 1 Or, if it vanishes, does the single star develop an- 

 tagonistic poles which move apart, each taking with it the half of the 

 great star left in the vitellus 1 



So far as one can judge from the observations that have hitherto ap- 

 peared, the most nearly complete second archiamphiaster yet seen is one 

 having a spherical central aster joined by a spindle to a very incomplete 

 peripheral aster, whose centre of radiation lies in the surface of the 

 vitellus. The latter in its greatest extension is less than the half of a 

 complete star. That there have been important omissions from the 

 history of the second archiamphiaster will at once be inferred upon 

 consulting Fig. 23. The first polar globule has already been formed, but 

 still remains loosely attached to the vitellus, and further held in place 

 by fragmentary portions of the surrounding albumen of the egg (a). 

 The second archiamphiaster is completely formed. Its axis coincides 

 almost exactly with the polar axis of the yolk. It lies wholly within 

 the vitellus, being nowhere tangent to its surface. The nearest point 

 of approach to the surface is immediately under the polar globule. The 

 composition of this second archaic figure is deserving of close attention. 

 The two stellate figures which make up the most of its substance are 

 joined by a spindle which is not very distinctly outlined. 



Perhaps the most noticeable feature of the whole figure is the un- 

 likeness of the two stars ; such a difterence as we have already seen 

 (Fig. 45) in the j^rs^ archiamphiaster. The outline of the deeper sphere 

 is by no means sharp, for prominent rays here and there extend into the 

 coarsely granular protoplasm for some distance beyond the majority of 

 the radiate fibres. In the case of the more superficial sphere, on the 

 other hand, the rays terminate at such a uniform distance from its cen- 

 tre that the outline is quite even, and almost circular, in whatever posi- 

 tion it be viewed. Otherwise the two asters are much alike : the rays 

 are straight in both, though more uniformly distinct in the outer than 

 in the deeper sphere. The centre of each is composed of a poorly de- 

 fined, not quite homogeneous refractive substance, as in corresponding 

 stages of the first archiamphiaster. 



The fibres joining the centres and together constituting the spindle 

 are, as usual, slightly curved, and they already present inconspicuous 

 thickenings in the equatorial zone. 



The gi'anulations of the vitellus, although for the most part evenly 



