No. 466.] STUDIES ON PLANT CELL.— VIII. 697 
Olive (:04) has given especial attention to methods of sec- 
tioning and staining on the slide and presents the most detailed 
account of the structure and behavior of the chromatin and the 
simple apparatus which brings about the division of the central 
body. The central body is made up chiefly of dense kinoplasm 
with a fibrillar structure in which lie chromosomes that may be 
counted and whose number is found to be constant in several 
species. Thus there are eight chromosomes in a species of 
Gloeocapsa and Nostoc and sixteen in certain forms of Oscilla- 
toria  Phormidium, and Calothrix.. The chromatin in some 
cases was observed to be organized into what seemed to bea 
simple type of spirem (especially clear in Gloeocapsa) within the 
central body, and the chromosomes are formed by a concentra- 
tion of material at certain points which are constant in the cells 
of the same plant. 
Olive found evidence that the chromosomes split during the 
process of division of the central body and are gathered in two 
groups at the ends of the achromatic structure which is gener- 
ally flattened at the poles and conforms in other particulars to 
the shape of the cells. The two sets of chromosomes are 
finally separated by the cell wall which develops from the pe- 
riphery during cell division and cuts the achromatic structure 
in the middle region. That portion of the central body which 
remains between the two sets of daughter chromosomes is 
regarded by Olive as equivalent to the central spindle so well 
defined in stages of anaphase and telophase in mitoses of higher 
plants. The central body during this process of division has 
certainly very much the appearance of a simple type of spindle 
although there are not present the large fibers so characteristic 
of nuclear figures in higher plants. Moreover it can scarcely 
be held that the division is one of simple fusion when chromo- 
somes are present in constant numbers and split into two groups 
with each division of the cell. Olive believes that the achro- 
matic structure, present during cell division, is a disc-shaped, 
generally flat-poled spindle, densely fibrous in structure and that 
the fission of the chromosomes and their separation into two 
sets constitutes a true mitotic division of the central body, which 
is a nucleus. 
