SOMATIC MITOSIS AND CHROMOSOME INDIVIDUALITY 149 



tions between the chromosomes of the reorganizing telophase nucleus 

 are formed in this way, at least in mitoses showing a tassement polaire 

 stage; but it is also probable, as several investigators have pointed out 

 that other anastomoses may grow out from one chromosome to anothei 

 in the manner of pseudopodia (Boveri 1904; Gates 1912; Strasburger 

 1905; Dehorne 1911; Muller 1912; Lundegardh). 



Reactions taking place between the various chromosomes and espec- 

 ially between them and the cytoplasm now result in the productioD of 

 the nuclear sap, or karyolymph. Between the outermost chromosomes 

 and the cytoplasm and also within the chromosome group droplets of 

 clear karyolymph appear, and where these come in contact with the 

 cytoplasm a nuclear membrane is formed. As the karyolymph increases 

 in amount the nucleus enlarg/es and the chromosomes become more 

 widely separated. 



The telophasic alveolation of the chromosomes, although it may in 

 exceptional cases begin much earlier, usually commences at about the 

 time the chromosomes first separate from one another in the earlv 

 reorganization stages of the daughter nucleus. Within each chromosome 

 vacuoles appear, first as obscure though rather sharply delimited circular 

 or elongated areas. They lie not only along the axis but also near 

 and against the periphery. This point is of importance in evaluating 

 the claim advanced by certain investigators (Lundegardh 1910, 1912; 

 Fraser and Snell 1911; Fraser 1914; Digby 1919) that the vacuolation 

 is median and results in a splitting of the chromosomes during the telo- 

 phase, rather than in the prophase. While the vacuoles develop into 

 open spaces through the breaking down of the thin portions bounding 

 them the nucleus increases rapidly in volume, so that each chromosome 

 appears as an irregular net-like band joined to its neighbors by fine anas- 

 tomoses. Careful study of the details of these telophasic changes (a 

 cross sections of chromosomes in Fig. 50, F) shows that the alveolation 

 proceeds with little regularity, and that each chromosome becomes an 

 alveolar and then reticulate body with nothing which can properly be 

 called a longitudinal split. 



In certain cases these internal changes, which result in the trans- 

 formation of the chromosomes into a reticulum, and which as a rule do not 

 begin until the telophase, may be initiated during the anaphase. In 

 Allium, for instance, Miss Merriman (1904), Lundegardh (1910, 19121 

 and Nemec (1910) all report that the vacuolation of the chromosomes 

 begins at this time. Even more striking is the case of Trillium (( iregoire 

 and Wygaerts 1903), in which the unusually large chromosomes may 

 show vacuoles as early as the metaphase (Fig. 54, -1). Internal changes 

 of other types have also been described in anaphase chromosomes, but 

 not with sufficient clearness to warrant their use in general interpre- 

 tations. 



