` 
1887] The Significance of Sex. 219 
THE SIGNIFICANCE OF SEX. 
BY JULIUS NELSON. 
(Concluded from page 162.) 
PLATE XI. 
Fic. 125, a—e. From the segmenting egg of the 4.xo/ot/— Bellonci, Arch. Italiennes 
de Biol., vi.—Shows how the knäuel reticulum is formed from the loops. The loops 
in this case are hook-shaped, or almost straight rods, the end of the segment which 
first reaches the pole swells out and the chromatin breaks up into microsomata, the 
whole segment is thus transformed into a vesicle containing peripheral microsomata. 
These vesicles fuse as in ç, æ, e, and the microsomata become arranged in rows, which 
thus form a reticulating filament. 
Fic, 126, a-k. Fertilization of ovum of Arion empiricorum—Platner, A. m. A., 
xxvii.—In æ we see the polar globule (fg) and the pro (sf), whose head 
and neck have “poten into the Bes but left the tail The head consists of a 
hyaline material holding two karyosomata. As usual ack rays surround it. 
germinal vesicle contains many cps mata, each with a hyaline envelope. e 
head of the spermatozoon at last becomes included in the germinal vesicle. In 4 we 
see the karyosomata have broken up into many microsomata arranged at the periph- 
ery of each hyaline vesicle, they fuse, so that for the most part, as in c, each shall 
wo microsomata at opposite sides. But the hyaline vesicles themselves fuse 
(or divide?) as indicated by the dumb-bell forms in 6. The hyaline mass of the male 
pronucleus divides, so each half has a karyosoma, and the latter passes through the 
same stages of segmentation and fusion as the female karyosoma, except that each 
vesicle has finally four microsomata instead of two (c, d, e sf). [Only the , -rminal 
vesicle or its contents are shown in all figures except a.] On the side of the 
vesicle towards the centre of the egg there arises an aster (c), and some 
into connection with it, the membrane of the germinal vesicle disappearing at this 
point. Ind a second aster has arisen, also near the first, so that the two are not 
at first opposite each other, but become so more and more by swinging around into a 
right line, and as they do so the germinal vesicle sinks towards the interior of the 
‘egg; ther RERA microsomata, like the first lot, now become connected with thi 
aster, except that the male karyosomata are behindhand (æ, e), but finally these 
join. Meanwhile ths microsomata become regularly disposed in an equatorial plate 
and grouped in fours, each pair of a four being united by a spindle-fibre to its own 
pole (f). Then each group of four microsomata fuse to form one karyosoma on each 
fibre _ g), and again segmenting into four (4), they separate, leaving connecting fibrils 
osomata move polewards there is a stage, as usual, where 
sy ine seem to fuse laterally (7). In 4 we see the spindle turned out of its position, 
leaving the two large polar asters i situ, but still possessing little ones of its own. 
Such is the history of the first segmentation after fertilization. By comparing it on 
the one side with Fig. 124, and on the other with Fig. 127, it is seen to form a con- 
necting link. 
Fic. sg a-f. A case of conjugation ing Vorticella microstomum—Engelmann, 
M. J., i.—When division or budding takes place the nucleus stretches into the bud 
and is CSE off. These buds are a sea SENS or males, and may suffer 
