190 BULLETIN OF THE 



nated as the animal pole. It is often spoken of as the formative pole, 

 in distinction from the opposite and often less active nutritive pole. 



In this condition, then, the egg manifests a diplopolar state, which 

 may — doubtless must — have had a potential existence before ; a state 

 which is now most emphatically expressed by its internal structure, 

 and which seems never to forsake it altogether. Whether, however, 

 this monaxial state be identical with that which one observes in the 

 earlier condition of the egg (Fig. 39) must be left undetermined for 

 the present. ' 



In this stage the maturation figure (i. e. the whole internal figure) 

 presents itself as a compound structure, composed of the spindle and 

 two nearly spherical masses of protoplasm, having the ends of the 

 spindle as centres, and traversed by fibres radiating from them, — in 

 short, the two asters of the so-called archiamphiaster. 



The length of the spindle is a little more than one third the diameter 

 of the vitellus, and its greatest thickness is somewhat less than half its 

 length. Its outline, when viewed en face, is evenly curved, tapering from 

 its greatest thickness at the equator toward either pole, where it is lost 

 in the rays near the centre of the aster. The spindle embraces a large 

 number of fibres, — probably not less than thirty or forty, — continuous 

 from pole to pole. These fibres are considerably more conspicuous than 

 the radiating lines of the asters. The intervening substance of the 

 spindle appears structureless, and much less refractive than the sub- 

 stance of the fibres. Some of the latter exhibit, in the equatorial plane 

 of the spindle, thickenings of considerable size. 



It does not seem that all the fibres present such thickenings ; nor, on 

 the other hand, am I quite certain but that some of these apparent 

 thickenings are really unconnected with any fibres, — at least their 

 irregular distribution has suggested the possibility of their being de- 

 tached, without having afforded as yet a sufiiciently satisfactory demon- 

 stration of the existence of such independent granules. A view along 

 the axis of the spindle (Fig. 46), while it affords pretty satisfactory 

 evidence as to the relative position of the thickenings in the equatorial 

 plane, does not prove sufficient to settle the question, for the reason 

 that the fibres are so minute as to be almost entirely obscured by the 

 overlying star. In the view thus had, one finds the number of thick- 

 enings to be about twenty, and that they are not distributed with any 

 very clearly defined order. In a later stage, however, we shall find that 

 the number is considerably greater, and that they are more conspicu- 

 ously subject to a definite plan of arrangement. 



