IQOS] YAMAXOUCHI—SPOROGENESIS IN NEPHRODIUM 15 



occur because of the bending and curving due to their being gathered 

 into the round cavity of the daughter nucleus. 



As the disappearance of the nuclear membrane approaches, V 

 elements become more distinctly pronounced {fig. 43), some of the 

 fine strands which branched out from V's disap}X'ar, but irregularity 

 in thickness persists and the arms of the V's end in ver>' slender 

 threads. The general outline of the nucleus up to this time is al\va}-s 

 flattened, so that the nucleus shows two different asi)ccts according to 



spore 



same 



may be, will always present two different side views, one being always 



narrower than the other. 



As the nuclear membrane breaks down, the cytoplasmic fibers 

 enter into the nuclear cavity, where the chromosomes are crowded 

 (fig. 44). The figure of this stage recalls the combined features of 



and 



chromosomes 





and curved, with daughter chromosomes in pairs 



those of the vegetative mitosis ; the achromatic fibers do not construct 

 a cap, but appear multipolar as in the heterotypic case, although they 

 are from the start observed near the nuclear membrane instead of at 



a distance from it. The two arms 

 the two daughter chromosomes c 



han 



angle {fig. 44) at which spindle fibers seem to become 

 attached. When the multipolar condition has passed into the bipolar 

 spindle, the angle ends of the V's, or the ends where spindle fibers 

 are attached, occupy the position near the pole, while the other ends 

 diverge toward the equatorial region {figs. 45, 4^)- T^^ f^^ 

 resembles that represented m fig. 3 ^ one of the transient conditions 



passing to the stage 



o 



arms of the V 's, or the daughter pair 



the bivalent chromosomes in this division, draw near to eacn omtr 

 untfl finaUy they come into close contact. Simultaneously, the bivalent 

 chromosoines. each consisting of two daughter chromosomes, move 



ard 



as the ultimate 



diromosomes to which fibers are attached are arranged m an equa- 

 torial plane, while the other free ends are directed toward the pok 

 {fig. 47). The figure of this stage is also comparable with that of the 



