i9o8] YAMANOUCHI-SPOROGENESIS IX XEPHRODIUM II 



already described. Now the tangled mass of the spircm begins to 

 uncoil (fig. 20) slowly; superficial parts of the spirem in the synaptic 

 mass at first become widely distributed, while the unraveling of the 

 inner parts of it arc naturally delayed, and the longitudinal separation 

 of the two independent parts is observable in the portions of the 

 spirem which are widely uncoiled {fig. 20). 



The spirem becomes considerably thickened, certainly due to 

 shortening, and becomes distributed loosely through the cavity; 

 while the line of the longitudinal splitting or separation of the spirem 

 into two elements seems obHteratcd, but its presence is evident in 



ih 



spircm again becomes irregular, and in some 



masses 



account of the twisting of the spirem itself, but double threads, the 

 constituents of the spirem, run mostly in close association {fig. 22). 

 Shortening and thickening of the spirem proceeds until it segments 

 into chromosomes. As sho\Mi in figs. 23a and 2j6, the segmentation 

 is not simultaneous throughout the entire spirem, but finally there 

 are formed 64 or 66 chromosomes, each bivalent in nature {figs. 



24a, h,c). 



The two hahes of the bivalent chromosomes lose their close asso- 

 ciation after then- segmentation, and show every possible position 



connection w^ith each other, such as H, I, J, K, L, 0, T, U, V, X, Y, 

 and so forth, and even give an impression of being of different 

 length and size, mostly due to the point of view. The chromatin 

 material which constitutes the surface region of the chromosomes 

 seems loosely aggregated, but it is compactly massed in the center, 

 and tliere are observed faintly stained substances of fibrillar form 

 attached at the ends of chromosomes, which seem to be remnants of 

 the material of the spirem left over at the time of segmentation, 



and 



loos 



probably on account of the viscid nature of the spirem. The 

 aggregated chromatin material is gradually dra^n and coi 

 toward the central part, but the condensation process take 

 irregularly, so that for a while the chromosomes appear spin} 

 chromosomes become shortened, and the loose fibrillar appendage 

 are also shortened by contributing material to the main body of thi 

 chromosome, yet some can still be seen {figs. 25a, b, c). 



The 



