AMERICAN 
JOURNAL OF BOTANY 
VOL. X 
July, 1923 
No. 7 
THE STRUCTURE OF THE CHROMOSOMES IN 
TRADESCANTIA VIRGINICA L. 
Harold C. Sands 
(Received for publication October 19, 1922) 
As a result of studies on the nuclei of Tradescantia virginica L., I am 
taking up previously discussed questions relating to the structure of the 
chromosome. 
That there is still little agreement in regard to this important problem 
is shown by the relatively recent papers of Bonnevie (1908), von Herwerden 
*(1910), Nawaschin (1911), Erhard (1910), Vejdovsky (1912), Lundegardh 
(1912a), Suessenguth (1921), and Martens (1922). 
An examination of the literature discloses a great volume of data bearing 
on this important subject, which perhaps originated with the much quoted 
paper of Balbiani (1881), in which he first called attention to striations on 
the chromatic filaments of the nucleus. 
Throughout this mass of literature, figures are given which represent 
appearances obtained by different methods of fixing, staining, and imbed¬ 
ding. As noted, the interpretations of these microscopic appearances in 
the chromosome vary widely, and are frequently influenced too much by 
attempts to harmonize the descriptions of them with what is believed to 
be true regarding their behavior. 
I shall restrict my description to certain stages: in the pollen mother 
cells, those from diakinesis (Hacker, 1905), to the arrangement of the 
chromosomes on the equatorial plate ( Sternfigur of Flemming) just prior 
to separation; and further, both in the pollen mother cells and the somatic 
cells, to the stages after complete separation has been effected, i.e., from 
the beginning of the anaphase to that telophase stage just prior to the 
reformation of the daughter nuclear membranes. I shall omit the series 
of processes involving the separation of the chromosomes during the meta¬ 
phases. 
The more intimate structure of the chromatic Faden or Schleifen has 
been much discussed for every point between these stages, but, in follow¬ 
ing the older authors, it is frequently difficult to know to which particular 
stage of the division figure the writer refers. Naturally, such ambiguities 
[The Journal for June (10: 275-342) was issued July 2, 1923]. 
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