142 The Significance of Sex. [ Feb. 
or microsomata which soon reach the granular state again (c, d, e). Meanwhile the 
nucleus flattens more and becomes biconcave; the granular protoplasm ane in 
concavities and sends across and through the nucleus the spindle-fibres (e); t 
marked boundary of the nucleus = dissolved, and the equatorial atone of cee 
splits and moves towards and into the polar masses, while the intervening portions of 
the ane -fibres (“ connecting aie) spread out and help build the cell-plate. 
117 is from Spirogyra nitida, where the nucleus is more spherical and the 
callie Bees are at first aggregated towards the centre in union with the central gran- 
ular mass of chromatin, and they become more spread out as the nucleus loses in 
outline and the chromatin is divided into its daughter portions. We see also that 
the latter is confined to the central fibres of the spindle. 
Fic. 118, a—dz. Nuclei from protoplasmic layer next wall of embryo-sac of Galan- 
thus nivalis—Strasburger, A. m. A., xxiii.—a, first step towards karyokinesis; the 
finely-wound “skein” or “tangle,” the meshes of whose reticulum give a finely gran- 
ular appearance to the protoplasm. A large nucleolus exists besides. This is dis- 
solving and adding itself to the filament in 4, where the boun aries between the 
microsomata are not indicated in the diagram. cis she “ segmented stage,” in which 
* 
around like hooks (only a few segments are shown). Next, the ot split — 
dinally, and the halves of each hook seek opposite poles; to do this there must be 
stage where one-half of the loops of the southern aA cross as equator on 
meet correspondin g hooks from the northern y to the southern hemisphere. 
(See d, where w and w are the corresponding sateen 4 the southern hooks, and x 
d the northern hooks. w/ and x’ are represented as having just crossed.) 
While this “ metakinesis” is progressing the hooks become more U-shaped, and 
taking the northern daughter-nucleus, as in dy, we can see how its skein-filament 
“is reconstituted in dz, by union of neighboring limbs of the sets of loops. (Meta- 
esis refers to the changes that take place after the splitting of the loops or micro- 
somata to form the chromatin figures which are to occupy the So The’ 
ing changes constitute the “ prophase,” the succeeding, the phase.’’) 
Fic. 119, a-/. From wall of embryo-sac of Fritillaria imperialis urger, 
A. m. A., xxiii—a-d represent the prophase, e-f, the metaphase, g-/, the anaphase. 
Here the first step of the metaphase is, as in the last case, one of mutual transfer be- 
tween the opposite sides of the equator. (See f.) Following any one loop in the 
- northern hemisphere, splitting into two halves (1, 2, Fig. fw), the part 2 is des- 
tined for the northern daughter-nucleus, and 1 for the southern. Separation between 
the two halves proceeds from one end to the other, so that the part 1 becomes pulled 
_ out straight, one limb of the part 2 is held back, while the other is dragged t towards 
its own pole (fx), both halves are therefore acted on so as to be pulled into line par- 
allel with a meridian, but the end, as it approaches the pole, bends around hook- 
-shaped to form a new loop, hence the part 2 passes through an “ S”? stage (fy), and 
the part 1 a hook stage, and they finally reach the U stage stage in fz, when the stages 
a ma oe, as in he preceding ane On comparing — it will be 
Hata 
Dever ai Gy 
ti d by means of the d 
a a PEN g Pee sake RUN a f the loops 
p but are oftener hooks or even straight filaments : 
and fx would be omitted. ; 
approximated. The number of Toop Sgr grrr grat ia 
e diagram, 
