lOO GARDINER. [Vol. X^^ 



soluble chromatin affords to the cytoplasm the material neces- 

 sary to supply this growth ? 



To return now to the growth of the first segmentation 

 spindle. By the time the chromatin has become condensed 

 into clumps the achromatic fibers have become much more dis- 

 tinct. As stated above, the rays from the aster centers seem 

 to grow down into the pronuclei (Fig. 35). This is a marked 

 contrast to what appears to take place in the formation of the 

 first maturation spindle. In this latter, when the nuclear wall 

 is dissolved the linin appears to flow out and form the 

 achromatic rays ; while in development of the segmentation 

 spindle the rays from the aster centers appear to grow down 

 into the pronuclei. It is of course possible that the linin into 

 which they grow affords material for that growth, but since the 

 bulk of these achromatic fibers soon far exceeds that of the 

 linin, it is evident that material is being elaborated from other 

 sources to form these rays. In the fully formed spindle 

 (Fig. 37) these rays are exceedingly large and distinct. 



As these fibers develop, an exceedingly strong cytoplasmic 

 network surrounds the whole spindle (Figs. 36 and 37). This 

 network is dotted with numerous microsomes which with iron 

 haematoxylin stain a deep blue, not unlike the centrosomes. 

 This network soon extends to the very uttermost limits of the 

 ovum, so that the first superficial section, which may cut off but 

 a very small portion of the ovum, reveals the network and fully 

 prepares the observer for the large spindle which deeper sec- 

 tions will disclose. As the network thus extends further into 

 the cytoplasm, the rays supporting it and connecting it with 

 the aster centers increase in size and length. In a former 

 paper (10) mention was made of the strange manner in which 

 certain pigment granules are moved about so as to lie in the 

 same plane as the equatorial plate, and reference (16) to simi- 

 lar observations in other ova is made. The size of the rays 

 and network in the ova is shown in Fig. 37 and also in Fig. 28, 

 where the polar globules are surrounded by the network. 



At the time when (10) was written I had sectioned but few 

 well-preserved ova and was unacquainted with the remarkable 

 structure of this spindle, but while examining certain pigment 



