270 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



are prominent and well defined, and may reach nearly to 

 the limiting membrane (figs. 24 to 26), while in other cases 

 they are merely small, ill-defined elevations. Free fibres, 

 which radiate out into the cytoplasm, persist for a time, but 

 gradually disappear. The cones are generally unequal, 

 some having larger, longer, more numerous and more 

 prominent fibres than others. 



The chromosomes preserve for a time their original 

 arrangement (fig. 25), but gradually become displaced and 

 irregularly scattered (figs. 25 and 26). The fibres in the 

 meantime combine to form more or less definite strands 

 which are at first irregular and loosely aggregated, but 

 which gradually become more compact and regular in 

 appearance. Gradually these strands or groups of fibres 

 become attached to the chromosomes; the attachment is at 

 first partial, involving only a few of the fibres of the strand, 

 but gradually extends to the other fibres of the group 



(fig. 26). 



5. Fascicular Stage. 



While the attachment of the fibrous strands to the chro- 

 mosomes is taking place the arrangement of the strands 

 themselves begins to undergo a change whereby they tend 

 to place themselves parallel to one another (fig. 26) ; at 

 the same time, certain cones lying at the ends of the in- 

 cipient spindle become increasingly prominent, and seem 

 to serve as places of assemblage for the other cones which 

 appear to gather around them, thus finally forming two 

 distinct groups which lie at the opposite ends of the fascicle 

 (fig. 28). In the meantime, the strands of fibres become 

 more and more compact, and form well defined, thick fibres 

 (fig. 27). 



The cones in each group gradually approach each other 

 more closely, and at the same time the number of cones 

 increases (fig. 28) ; the fusion of the cones is gradual, and 

 frequently takes place sooner at one end of the spindle 

 than at the other (fig. 28). The assemblage of chromo- 

 somes in the equatorial plate does not take place until the 

 fusion is well advanced. 



