476 Carter . — The Cytology of the Cladophoraceae . 
indistinct daughter spireme and finally the typical resting nucleus with one 
or more nucleoli (Figs. 20-3 and 35-7). 
Some very peculiar nuclear division figures at the anaphase stage were 
observed in Cladophora glomerata, var. fascicidcita, (Kiitz.) Brand. In these 
nuclei the migration of the chromosomes to opposite poles was extremely 
disorderly, the chromosomes following one after the other in an irregular 
fashion instead of being pulled apart by the fibres of the spindle in two compact 
masses, whilst the spindle itself was often bent (Figs. 38-40). These peculiar, 
stages were taken from segments in which rapid nuclear division was taking 
place preparatory to the formation of zoogonidia, but whether this apparently 
abnormal mitotic figure is general in such cases could not be ascertained. 
Summary. 
Thechloroplast in Cladophora , Chaetomorpha , and Rhizoclonium consists 
invariably of a parietal film lining the cell-wall and often more or less per- 
forated or reticulated according to the relative abundance of the cell-contents. 
In most cells with plentiful contents there arise from this lining layer irregu- 
lar strands which traverse the lumen of the cell, and in many cases are so 
numerous that they occupy a considerable part of the cell-cavity. In mature 
cells, or cells with very scanty cell-contents, this internal network of chloro- 
plast may be wanting. 
Pyrenoids are very numerous and are scattered in both the peripheral 
and internal parts of the chloroplast. 
Colourless cytoplasm is very difficult to distinguish except where the 
lining parietal layer of chloroplast is perforated, and the nuclei are almost 
invariably confined to the chloroplast, not. being found as a general rule in 
the colourless cytoplasm. 
In some narrow forms of Rhizoclonium the nuclei are of large size in 
comparison with the small diameter of the cell, and in these the nuclei may 
not be wholly immersed in the chloroplast, but may often project into the 
cavity of the cell. 
The nuclei in Rhizoclonium hieroglyphicum are not so restricted in num- 
ber as was formerly believed to be the case, since in some thick forms they 
frequently number twenty-four in a cell. 
In the autumn much starch is accumulated and is stored in the form of 
small grains, which are lodged in the interstices of the protoplasmic reticulum 
of the chloroplast. As a result of this the chloroplast becomes very dis- 
tended, and occupies relatively much more of the cell-cavity. 
During mitosis the nucleus of Rhizoclonium and Cladophora is charac- 
terized by the formation of a long thin spireme, which gives rise to very 
numerous chromosomes. After the migration of these to opposite poles of 
the spindle the daughter nuclei are separated by constriction of the spindle 
in the region of the equator. 
