3o6 LESTER "W. SHARP 



splitting of the chromosomes, which will receive full considération later. 

 As the vacuoles increase in size they become correspondingly clearer. 



While the vacuoles develop into open spaces through the breaking 

 down of thin portions bounding them the nuclear cavity increases rapidly 

 in size, so that each chromosome stands out sharply as a ragged chromatic 

 band joined to its neighbors by fine anastomoses, fig. 37. Attention is di- 

 rected to the détails of this vacuolization. In fig. 38 are shown several 

 chromosomes or portions of chromosomes from différent nuclei of about 

 the stage of fig. 37. Thèse figures hâve been drawn with the greatest care 

 in order to convey as accurate as possible an idea of the true structure of 

 the chromosomes as they appear in the préparations. In fig. 38c7 the va- 

 cuoles are so placed in the lower portion of the right hand chromosome as 

 to give to the chromatic portion a spiral aspect. The same is true of a 

 portion of the smaller chromosome in fig. 38/?. On the other hand, in 

 FIG. 38c, J, c, are shown several cases of vacuolization more or less along 

 the médian Une, which, if examined superficially without careful compari- 

 son with many other chromosomes, lead to the conclusion that a longitudi- 

 nal split has occurred. Fig. 38/, i^'', h, represents examples of vacuolization 

 almost wholly along the margins. From a careful considération of thèse 

 figures, to which many similar ones might be added, we can only conclude 

 that the telophasic vacuolization proceeds absolutely without regularity, 

 that each chromosome becomes an irregular alveolar and then reticulate 

 band with nothing which can properly be called a longitudinal split. 



Since thèse points are to be taken up in the gênerai discussion, only a 

 rapid survey of the literature of the subject will be presented hère, in or- 

 der that the relation of the présent results to those of other workers may 

 be kept in mind. The account given above corresponds essentially to that 

 given by Grégoire and Wygaerts (o3) for Trilliiim, and by Grégoire (o6) 

 for Allium. Karpoff (04) in his inadéquate figures of -^ stellate bands ^ 

 in Vicia at least suggests alveolization at the telophase. According to Miss 

 Merriman (04) the chromosomes of Allium break up at telophase to form 

 a tetrad structure without any true alveolization. On igoS and igii 

 BoNNEViE published her striking results on Ascaris, Alliuin, and Am- 

 phiiima. In thèse accounts the chromosomes are described as each giving 

 origin to an endogenous spiral chromatic thread which persists through the 

 resting stages and in prophase again condenses to a chromosome. The 

 figures given by Yamanouchi (08) of Nephrodium indicate a gênerai telo- 



