150 . The Significance of Sex. [ Feb. 
knauel stage, until it shows as a rosette (Fig. 111, e), with loops 
turned peripherally and towards the centre. Then the outer 
limbs of the loops break, leaving a lot of V-shaped filaments 
having their apices towards a common centre. (Fig. 105, 7.) This 
is the “ mother-star.” Meanwhile the central point of attraction 
splits and movés to the poles, where asters now appear. This 
is accompanied by alternate expansion and contraction of the 
nuclear star (diastole and systole), and finally results in its flat- 
tening into an “ equatorial plate” (Fig. 113, Æ); then each loop 
splits lengthwise, though it may have done so while still in the 
mother-star (Fig. 119, ¢), and thus formed the “ fine-rayed star.” 
The halves of each loop become separated and grouped in a 
“ dyaster,” or two daughter-stars, passing through the phase 
which shows as a splitting of the equatorial plate. Then the 
apices of the loops (travelling along the spindle-fibres) are drawn 
towards the poles (Fig. 112, ¢), drawing the limbs after them, and 
so reach the pole. Here they form into a figure like the old 
mother-star (Figs. 112, f, 105, 4), and return, by uniting ends 
through the rosette (Fig. 118, f) into the knauel form, and finally 
become like the mother-nucleus. 
The next year Flemming divided cell-division into direct and 
indirect. He limited the former to motile cells, and accepted 
Schleicher’s term as applying to the indirect kind. He thinks 
the nucleoli are an accidental thing in a nucleus, and according 
as nuclear substance stains or not he calls it chromatin and achro- 
matin. In the same year, 1879, Fol proposed his electrolytic 
theory of cell-division. He believed the nuclear reticulum was 
directly transformed into the spindle, and the nuclear plate was 
due to an equatorial thickening of its fibres. 
Strasburger's studies gave him different results from Flemming. 
In plants the phases are not so marked, but may give a spindle 
figure of chromatic granules arranged in rows like the staves of 
a cask; and the daughter-nuclei arise through the simple break- 
ing of these across the middle. (Figs. 115, a-d.) ` 
In 1881, Retzius had confirmed the phases of Flemming, but 
showed that the rosette must be given up, as segmentation of the 
knauel may take place while in the loose or open knauel stage. 
_ (Fig. 112, 6.) He says the chromatic substance is contained in a 
= hyaline matrix, as Pfitzner has shown, and most of it is absorbed 
: a and these are the nucleoli. p 
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