1S95.] 471 [Wilson. 
tiniill^' (Uvitles into two lialves wliic-h i»laoe tlieniselves at opposite 
j)oles of the nucleus. 
The rays of these asters, wliich are extremely long and con- 
spicuous, stain blue in iron-haematoxylin and Congo red, and 
close examination shows that they are composed of minute 
granules or microsomes similar to those of the general reticulum 
but somewhat smaller. The central body of the aster stains 
bright red and at this period appears as a fine granular or 
reticulated mass. The same structure may be made out in the 
undivided sperm-aster from its very beginning; and a similar 
color-contrast appears between the rays and the central mass, 
though less marked than in the later stages. At their outer ends 
the rays l)ranch out into the general reticulum. 
The nucleus now rapidly inci-eases in size, while the aster 
becomes less consj)icuous. The rays become very short and 
more distinctly graniilar, while the central red-staining mass 
increases in si/.e. This condition, which may l)e called the 
"pause," continues for some time (fifteen or twenty minutes), 
after which the cleavage-amphiaster is rai»id]y formed in the 
following manner. The astral rays rapidly extend themselves 
again from the central mass or archoplasm-sphere at each pole 
of the nucleus. Some of these rays lie within the nucleus and 
thus form the spindle which is directly differentiated out of the 
achi-omatic nuclear sul)stance, and in this process the nuclear 
memlirane appai-ently takes part. The chromatic reticulum 
meanwhile resolves itself into the chromosomes, an equatorial 
plate is formed, and a typical karyokinetic figure results. 
During the anaphase the central red-staining archoplasm-mass 
rapidly enlarges, and its structure can now be very clearly seen 
and is shown with peculiar distinctness in the i)hotographs. It 
contains no centrosomes, as figured by Fol, but consists of an 
irregular, fine-meshed network into which the blue astral rays are 
continued at their inner ends. 
Throughout all of the preceding stages there is not at any time 
the slightest indication of an egg-centrosome or an cgg-archo- 
plasm (" ovocentre " of Fol) as distinguished from the sperm- 
archoplasm. The entire substance of the cleavage-amphiaster is 
directly derived from the sperm-aster, and this in turn may l^e 
