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AMERICAN JOURNAL OF BOTANY 
[Vol. io, 
Baranetzky (1880) first studied chromosome structure in Tradescantia 
virginica L. He notes that: 
Die Scharfe und die Regelmassigkeit des Baues ist oft so gross, dass beim ersten Anblick 
die Kernfaden unwillkurlich an die aus platten Zellen bestehenden Oscillarienfaden erinnern. 
He further notes that the contours of the chromosome outlines are finely 
wavy owing to a slight constriction of the Zwischensubstanz between the 
disks. He describes the splitting of the chromosomal disks as taking place 
at right angles to the long axis of the chromosomes, and further states 
that the cleft begins at the surface of the disk and proceeds toward the 
center without good evidence that he has actually observed the process. 
Baranetzky also reports the same structure of the chromosomes for Agapan- 
thus, Hemerocallis, Yucca, Hesperis, Lathyrus, and Pisum. 
Erhard’s (1910) aberrant ideas as to the relation of the chromatin and 
the nucleus need hardly be considered. 
Pfitzner (1882) described the chromatic threads of the nuclei of many 
different tissues as being made up of granules, the "Pfitzner granules” 
(text fig. 4). 
It is to be emphasized that there is practically no disagreement on the 
point that this construction obtains for the prophase stages. One of the 
first to point this out was Hermann in 1891. Almost every investigator 
has figured the chromatin bodies at this stage, notably Flemming (1879), 
Strasburger (1882), Bonnevie (1908), Vejdovsky (1912), and others too 
numerous to mention. 
Flemming (1882), working with fixed material, recognized the granular 
composition of the chromosomes throughout the process of division (text 
fig. 5). His figures of the prophases, equatorial plate, anaphases, and 
telophases show an almost diagrammatic regularity in the arrangement of 
the chromatic granules. He explains the granular structure of the longi¬ 
tudinal halves of the chromosomes in the monaster by ascribing the apparent 
loss of chromosomal continuity to the same effect of fixing reagents which 
causes, in the earlier stages, the obliteration of the split in the chromatic 
filaments. 
Strasburger (1884), working on Tradescantia, recognizes the Pfitzner 
granules as microsome disks and the Zwischensubstanz as hyaloplasm. He 
also claims, for the early prophase, that the material of the chromosomes 
may be in the form of a slender spiral. In his figures 63, 64, and 65 a, b, 
d , Plate XIV, he clearly shows the constricted surface outlines of the chromo¬ 
somes in the metaphases, and in figure 49 of the same plate he shows it 
in the anaphases. 
Miss King (1901), working on Bufo lentiginosus, finds the chromosomes 
of the ovum to be composed of microsomes. 
Vejdovsky (1907) discusses the granular construction of the chromo¬ 
some as described by Flemming. He says that young chromosomes do 
not consist of a homogeneous substance, but show a pale substratum on 
