SOMATIC CHROMOSOMES IN VICIA 3o3 



writer cannot agrée, since the stage in question is found in material fixed 

 in eacli of tlie several fluids used, and in the cells of ail régions of the root 

 where fixation is otherwise excellent. 



Dehorne (ii) in his account of Salamandra and Allium reports the 

 pairing of the chromosomes at anaphase, and further holds that each chro- 

 mosome becomes completely split at this time. The présent investigation 

 of Vicia does not support either of thèse claims. It is true that two chro- 

 mosomes may at times lie near each other or even in contact, forming 

 anastomoses. Such a case is shown in fig. A, but the phenomenon is of too 

 rare occurrence to hâve any essential meaning in mitosis. 



Concerning the structure of the chromosome during anaphase there is 

 much différence of opinion. According to Miss Merriman (04) the chromo- 

 somes of Allium hâve at anaphase a tubular structure which soon becomes 

 quadripartite, being truly split. The interprétation of Bonnevie (08) is just 

 the reverse of this, the cross section showing at first a tetrad structure 

 which later becomes circular. The chromatic material is denser at the 

 periphery, so that the axial portion of the chromosome appears lighter. It 

 is important to distinguish between this view and that of Merriman (04) 

 and of LuNDEGARDH (10, 12b). The latter authors hold that the axis of 

 the chromosome is vacuolized, while Bonnevie regards the chromosome as 

 solid, but differentiated into a heavy outer portion and a less dense in- 

 terior. Lundegâkdh considers the axial vacuolization which he sees in 

 Allium and Vicia as a true split. Nëmec (10) also describes in Allium an ana- 

 phasic vacuolization, often axial, but does not interpret it as a split. Fraser 

 and Snell (ii) see no change in the chromosomes of Vicia until telophase. 



In a séries of specially decolorized préparations of weak Flemming 

 material the writer has made the following observations. At late prophase 

 the stain is extracted rapidly from thechromosomes, leavingirregularstained 

 patches standing out in sharp contrast to the pale decolorized portions, 

 FIG. B. The action of the decolorizing agent in gênerai begins at the sur- 

 face and Works gradually inward. If allowed to act for a longer time the 

 chromosomes become uniformly pale. At metaphase the same condition 

 obtains, fig. C; as yet there appears to be little or no differentiation in the 

 pale portion. At anaphase, however, it is seen, fig. D, that the margins of 

 the chromosome retain the color a little more than does the inner portion, 

 At late anaphase, fig. E, the differentiation is very distinct, and is seen 

 especially well in cross sections of the chromosomes. The stain is extracted 



39 



