332 
NOTES AND MEMORANDA. 
spherical, whilst continuing united to one anotlier by the bundle or 
little band of fibrillte just formed. These two extremities thus con- 
stitute two spherical nuclei, finely granulated, between which exists the 
little band of fibrillm whose extremities remain in continuity with these 
new nuclei. Gradually the little band of fibrillae becomes attenuated 
towards the middle of its length, as if it were drawn out, and folds up 
more or less on itself, in such a way as to bring the two nuclei nearer 
to each other. This attenuation soon leads to the rupture of the con- 
tinuity of the fibrillEe, of which each half then gradually withdraws 
into that one of the two new nuclei to which it had remained attached 
by one end. The bisegmentation is thus complete from an hour, to 
an hour and a half at most, after its commencement, j)resenting, in 
one individual with another, varieties of secondary importance as well 
as a few other peculiarities not pointed out here. 
At the same time the layer of sarcodic substance (protoplasm), 
which is in immediate contact with the nucleus, is segmented without 
showing anything peculiar. But the whole of the sarcodic filaments, 
anastomosed into a network which is spread around the above- 
mentioned layer, present some curious phases of segmentation. The 
extreme peripheric portion of this network is condensed into a thin 
yellowish layer or bordering, circumscribing that part of this reticulum 
which remains interposed between this homogeneous bordering and 
the equally homogeneous layer in contact with the nucleus. The 
whole contracts itself “ en hissac ” with a wrinkling of the surface, 
simulating torsion of the sarcodic substance, at the level of the con- 
striction of the nucleus which precedes its division. The contraction 
of this “ hissac ” increases and culminates in a complete separation or 
segmentation of the sarcodic substance, which ends a few minutes 
after the completion of the nuclear fission. Afterwards, the substance 
forming a peripheral bordering to the reticulum, gradually approaches 
the perinuclear homologous layer (in consequence of the contraction 
of the intermediate network itself) until the latter disappears and the 
whole is blended into a yellow’ish, homogeneous, cellular body, with 
an undulating surface, lodged in a projection, corresponding to a 
gemma, of the wall of the body of the parent animal. 
That is the case until the end of this double formation by 
simultaneous segmentation and gemmation, associated together in the 
gemmiparous reproduction of the Noctilucge. The wall of each 
gemma and its cellular contents contract at their point of continuity 
with their homologues of the unicellular parent, and separate from them 
when the length of each is reduced to an average of *018 mm., that is 
to say, when their number is either 256 or 512. They are so many 
new unicellular individuals like the one which generates them (to die 
afterwards), and which from the time of their ulterior evolutionary 
growth, always remain unicellular. At least no evolutionary phase 
higher than the tentaculated form has up to the present time been 
observed. 
Before the gemmae are completely separated from the parent and 
swim freely, a flagellum six or seven times their length is deve- 
loped on their plane surface (the other being rounded), nearer to their 
