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June. 1921.] KUWADA:— LONGITUDINAL SPLIT OF CHROMOSOMES IQl 



A light space along the median line of chromosomes is seen in 

 every chromosome in the telophase ; its structure is difficult to see in 

 the beginning of the stage, and it seems just like a split, but later, 

 when the vacuolization of chromosomes progresses further, it becomes 

 clearer. The chromosomes take a form of a reticulate band consist- 

 ing mostly of a row of meshes. In Fig. 2, drawn from a piece of a 

 telophasic nucleus, three of these reticulate bands, each representing 

 a chromosome or a part of one, are seen. The band in the upper 

 line shows a feature resembling a split in the left half, while in the 

 half towards the right a zigzag chromatic thread, formed by the 

 breaking down of one side of the meshes, is visible. In the second 

 band, can be seen nearly the same aspect as that of the left hand 

 side of the first band, while the last one consists of a regular row 

 of meshes. This preparation is made from material fixed with Flem 

 ming's strong solution for 12 hours. The material was not so well 

 fixed as was that with the same solvition for 24 hours. Fig. 1 is 

 drawn from a preparation made from material fixed with Flemming's 

 strong solution for 24 hours. The details of the band here ewe more 

 clearly shown than those in Fig. 2. The thick parts in the meshes of 

 the band present a somewhat zigzag or spiral appearance, a feature 

 which is very much like that in the early prophase, as we shall see 

 later. That this nucleus is in the telophase is apparent, from the fact 

 that in the next cell there is a piece of a nucleus, in which chromo- 

 somes, just in the same stage as those in Fig. 1, are present. 



From both sides of tlie band the substance becomes drawn out 

 to form anastomoses with other chromosomes, and thus the nucleus 

 gradually enters the resting stage. Fig. 3 and the uppermost chro- 

 mosome in Fig. 1 show these processes. When the preparation for 

 the next division begins, the anastomoses gradually disappear, and 

 individual chromosomes become distinct again, as they were in the 

 preceding telophase, retaining their form of a reticulate band. The 

 mesh-work is, however, never so simple in general, as in the telo- 

 phase, but much more complicated. This may be due to the fact that 

 the anastomoses of chromatic substances had highly "developed before 

 the nucleus reached a complete resting stage. These old chromosomes 

 mostly run parallel with each other as they were when thej-^ entered 

 the telophase. New chromosomes begin to appear inside the old 

 chromosomes in the form of a single, zigzag or little coiled thread, 

 and not as a double tkread. The general feature is very much like 

 the vacuolated chromosomes in the telophase (Fig. 1). In agreement 



