1909] YAMANOUCHI— MITOSIS IN FUCUS 195 



Fig. 42a.— Nucleus from fig. 42, under higher magnification: chromatin 

 threads very much tangled; centrosome not shown here. 



Figs. 43a, 436, 43c. — Three sections of the same nucleus in synapsis: chromatin 

 threads in form of loops becoming attached by their ends to a part of the nuclear 

 membrane, outside of which there lies a centrosome with radiations. 



Figs. 44a, 44b.— Two sections of the same nucleus in synapsis, similar stage to 

 above: there a black staining body associated with a nucleolus. 



Fig. 45.— Section through the base of crowded loops, at contact with the 

 nuclear membrane, showing 60 or more isolated chromatin dots, some of them 

 connecting with one another; the dots are either the ends of the loops or their 

 optical sections. 



Fig. 46.— Nucleus emerging from synapsis: chromatin loops moving from the 

 place of aggregation in synapsis; two arms of each of these loops are always in 

 close association, forming bivalent chromosomes; centrosome in next section. 



Figs. 47a, 4 jb, 47c— Three sections of the same nucleus in prophase: 32 

 bivalent chromosomes; now two centrosomes lie at two poles, one of the centro- 

 somes being newly formed, independent of the other that appeared at a previous 

 stage; some of spindle fibers beginning to intrude into the nuclear cavity. 



Figs. 48a, 486.— Two sections of the same oogonium: 32 bivalent chromo- 

 somes; these figures show the case where there is still only one centrosome. 



Figs. 49a, 496.— Two sections of the same nucleus in prophase: two poles 

 ess than 180 apart; intruding fibers attaching to chromosomes. 



Fig. 50.— Early metaphase: intranuclear figure established, its axis parallel 

 to that of oogonium. 



Fig. 5°a.--Intranuclear figure in prophase from fig. 50, under higher magni- 

 Catl0n: rem "ant of nucleolus still visible near the spindle. 



PLATE X 



theft 10 5l '~~ Meta P hase a little later than the stage in fig. 50, with the axis of 

 6 p gUre at ri Sht angles to that of the previous one. 



ic. sia.— Xu C i eus from fo under hi her notification: the nuclear 



^brane ha * disappeared. 



raiddl IGS 52<I ' S2b ' S2C -~ Three sections of the same nucleus in metaphase: the 

 e section shows 32 bivalent chromosomes, although their bivalent nature 

 » hardly discernible. 



undi t\ 33 '""" Ana P hase: the case where the contour of the nucleus still remains 



curbed even after the dissolution of its membrane, 

 tion ' 54, ~~ Xucle us in anaphase, similar stage to fig. 53, under higher magnifica- 



s howin 5 h 5 \~ Portion of °ne set of daughter chromosomes in late anaphase, 

 F "g their rod-shape while attached to the spindle fibers. 

 Fig 5 rophase of the second mitosis in the oogonium : two figures similar. 



i ntrann'i 56a '^ Nudeus from fiS- 5 6 , " n der higher magnification: the figure is 



ear; nucleolus still remains. 



