556 
investment, either adipose or peritoneal, except 
only what belongs to itse!f; but is closely sur- 
rounded by cells of the second and third size 
On the tenth day the great circulatory or 
dorsal vessel was distinctly seen through the 
amnion and skin. This doubtless had existed 
much earlier, although not observed. It was 
exceedingly well marked, but Mr. Newport was 
as yet unable to detect any motion in it. The 
head of the embryo had now begun to assume 
the poe corneous appearance common to 
the larve of true insects; its body had much 
increased in size, and the amnion was still co- 
vered with microscopic drops of fluid. 
On the eleventh day the head was more dis- 
tinct, and the antenne appeared at its sides 
like short crescent-shaped clubs, with their 
terminations directed forwards. Above them 
the single ocelli were distinctly seen. All 
the segments, posterior to the third, exhibited 
the transverse line that indicated the division 
into double segments, and the posterior seg- 
ments were much increased in size. 
On the morning of the seventeenth day (fig. 
321) Mr. Newport found all the embryos ready 
to leave the amnion. ; 
Some of them were al- Fig. 321. 
ready detached from the — 
shell ; others were still 
connected to it. Their 
increase of bulk within 
the last few hours had 
been very great. The 
body was now more 
straightened, the head 
less inflected under the 
thorax, and the eye was 
a dark-coloured spot 
above and behind the wae 
antenne. The segments of the body were di- 
vided by distinct reduplicatures of the proper 
tegument, and the legs folded side by side 
against the ventral surface were much further 
extended beneath the amnion (b, a). The trans- 
verse divisions of the first six segments strongly 
marked the original segments, and the amnion, 
now about to burst, was tightly extended over 
the dorsal surface, and by the elongation of the 
body was rendered more distinct on the ventral. 
The great increase in the length of the animal 
was mainly occasioned by the growth of the 
posterior segments, more especially those in 
the antepenultimate space, the proper germinal 
space or membrane (f°), the faint divisions of 
which into new segments were now distinctly 
seen through the amnion. The seven anterior 
segments, including the head, were greatly en- 
larged, and the hitherto minute anal an 
nultimate segments (8, 9), in the first of which 
the remains of the funis (d) forms a rudimen- 
tary spine, had also become enlarged, and were 
now fast acquiring the form they afterwards 
retain throughout the life of the animal. Some 
of the specimens soon threw off their covering 
and entered the third period of development. 
The animal was now shang omar and 
possessed three pairs of legs, but it still la 
with these Seiktp ‘davaloped legs coiled wid 
without voluntary motion. The amnion had 
MYRIAPODA. 
been fissured at its anterior dorsal surface, and 
slipped off backwards from the i g- 
ments, and Jay at the anal extremity, while 
animal itself, with its limbs coiled up, app 
as if exhausted with these its first spontar ous 
efforts. No other signs of anima enc 
were given than occasional slight moven 
of the antenne. The embryos thus passe 
from their apparently inanimate to an animat 
state of existence, from a condition in whic 
they appeared merely to vegetate, endoy 
with no voluntary or instinctive p 
like the vegetable formed entirely of an agg 
gation of cells, totally incapable of spontaneot 
motion, to one in which they became activ 
beings, gradually acquiring voluntary and it 
stinctive faculties both as regards ‘mean: 
of precuring nourishment and of f i 
themselves from injury. 
In about an hour after leaving the amnik 
the young Julus exhibited a marked che 
Its head was elongated on the prothorax (2 
the parts of the mouth were distinctly mov 
able, and the eye, a single ocellus on each Si 
of the head, acquired a darker colour. The 
whole body had been increased at least on 
fourth in bu!k since leaving the amnion. — 
now measured about a line in length, and € 
hibited very distinctly the nine a é 
ments. e seven anterior of these we 
strongly marked. In the germinal space, ( 
321, /;) between the original seventh 
segments, six new segments were now develo 
These were still very small, the length of t 
whole being equal only to that of one of t 
original segments. At the present time t 
did not form independent divisions of the be 
ate were covered by the common tegument, 4 
thus appeared like supplementary f t 
serena dapeiont scdenaa from mi 
membrane and interposed between the sever 
and the penultimate segment (8), which, as 
fore stated, is a permanent segment througl 
the life of the animal. This latter fact shews 
it is not merely by an elongation and divi: 
of the terminal segment that the body of 
Julus is developed, but that it arrives at 
fect state by an actual production of 
new segments; that these are new growths 
formations which are in progress long bt 
they are apparent to the eye, and that 
original segments of the ovum into whic 
animal is first moulded are permanent segi 
throughout its whole life. ; 
But still more curious is it that not only 
new segments been formed as described, 
that the common tegument by which the 
now covered and which also invests the ¥ 
body as the true skin, has already begun 
detached preparatory to its being thrown 
is shewn in the fact that the new segment 
now seen beneath it; and it is further ren 
able that this deciduation of the first skit 
the animal had actually commenced befor 
bursting of the amnion. These cireums 
explain the cause of the very quiescent sta 
the young Julus, and its almost and perh 
entire abstinence from food whilst this” 
remains on its body. It is not until 
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ee 
pe 
