1909] 



Y AM ANOUCHI— MITOSIS IN FUCUS 181 



are evidently formed by the folding back repeatedly of long con- 

 tinuous threads, the blunt ends of which protrude toward the cavity, 

 while the opposite ends become closely attached to the nuclear 

 membrane (figs. 43a, b, c; 44a, b). The loops are therefore not 

 independent of one another, but are connected also at the base, which 

 is in contact with the membrane in such a way that an arm of one loop, 

 by turning back, passes directly to the arm of the next loop. These 

 connections of the loops at the base are detached and there results 

 a number of loops in synapsis. The number of the loops is not 

 easily counted from profile views ; however, a section cut transversely 



arms 



loops (fig. 4j). Consequently, the number of loops is 32, each loop 

 consisting of two arms. 



The loops differ at first in their thickness and length, but by 

 thickening and shortening they gradually become similar, a change 

 *'hich is more rapid in the thinner and longer ones. The loops 

 now become more closely associated with one another during the 

 culmination of synapsis. The two arms of each of these loops in 

 contact with each other gradually become more compact and con- 

 sequently appear smaller. The two arms of each of these loops then 

 separate at the bend— the point of connection— and form a pair of 

 bivalent chromosomes in prophase of the first division. The bivalent 

 chromosomes remain for a while at the spot where they were grouped 



46) 



(fig 



nema 



ery much modified 



m — -^ -l-^-^p * ■ ■ ^^ ^W*» V 



Some attention was paid to the centrosome. When 



plasmic 



midst 



The 



ded 



centrosome with its radiations is always in association with the 

 synaptic group of loops. When the bivalent chromosomes are 



(figs. 47a 



first 



monies 180 apart from it, but often not so far away (fig 



b e £ entr °some within the kinoplasm sometimes fragments 



u then they remain side bv side without separating or esl 



n 



