part of the cephalo-thorax, constitutes the brain, and sends forward nerves to the eyes and
falces. The narrow oesophagus is inclQsed by a short and thick collar, which expands into a
large thoracic ganglion, having small, conoid projections at its sides, from whose apices
nerves are distributed to the legs and palpi; and a double, longitudinal, nervous chord,
extending from the thoracic ganglion into the abdomen, has its extremity dilated, and from this
enlargement a great number of nerves pass off to the organs contained in the abdominal cavity.
Comprised within the cephalo-thorax, to whose integuments they are firmly attached, are
the muscles which give motion to the legs, falces, maxillae, and palpi.
Nothing is known with certainty concerning the organs of smell and hearing in spiders.
As regards taste, the choice which these animals make of their food sufficiently indicates that
it exists, and it is probable that the organ. is situated at the entrance of the pharynx.
Numerous circumstances tend to prove that spiders are endowed with considerable delicacy
of touch, but , the instruments more especially adapted to bring them into relation with
surrounding objects are the legs and palpi. The presence of eyes, which are of the kind
termed simple, in opposition to those of insects and crustaceous animals, which are denominated
compound, leaves no doubt relative to the sight of spiders, though, in all probability, they see
objects distinctly at short distances only.
When spiders are about to deposit their eggs they usually spin silken cocoons for their
reception, which exhibit much diversity of form, colour, and consistency, and are placed in
various situations, according to the economy of the species by which they are fabricated.
Many spiders abandon their cocoons so soon as they are completed; others manifest great
attachment to them, watching over them with the utmost solicitude ; and some, connecting
them with the spinners by silken lines, or grasping them with the falces and palpi, transport
them wherever they move. In numerous instances the eggs are agglutinated together into a
compact mass; in others they are united by filaments of silk ; and not unfrequently they are
entirely free or unconnected. Their figure is either spherical, or somewhat elliptical; and
their predominant colours are yellowish-white, yellow, orange-yellow, brown, and pink.
Several sets of prolific eggs are frequently laid in succession, an interval of many months
occasionally intervening between the extramission of two consecutive sets, by females which
have not associated with males of their species after they have deposited the first s e t; but
eggs produced without sexual intercourse are always sterile. For a knowledge of the various
changes which take place in the ova of spiders previously to the extrusion of the young we
are indebted to M. Herold,1 whose highly interesting and important observations may be
consulted with advantage by physiologists. The exterior covering of the egg consists of a very
delicate membrane, in whose composition no pore or fibre has been perceived. Within this
membrane there is a liquid in which several essential parts may be distinguished corresponding
to the vitellus, the albumen, and the cicatricula in the eggs of birds.
On the disengagement of young spiders from the egg, every part is enclosed in a
membraneous envelope; they are embarrassed in their movements, are unable to spin or to
seize their prey, and seem to be indisposed to action. For the unrestrained exercise of these
functions it is requisite that they should extricate themselves from the covering which impedes
them; and this operation, or, as it may be termed, their first moult, occurs after a period
1 * De Generatione Arauearum in ovo/ folio, Marburg, 1824.
whose duration is regulated principally by the temperature and moisture of the atmosphere.
The moult invariably takes place in the cocoon or general envelope of the eggs, and the young
spiders do not quit this common nest till the weather is mild and genial. They then commonly
disperse; but the young of some species continue to live together for a considerable time, and
in many instances are supplied, with sustenance by the mother. On deserting the cocoon the
Lycosa attach themselves to the body of their parent, who carries them with her till they are
able to provide for themselves.
Before they arrive at maturity spiders change their integument several times; the manner
in which these moults are effected may be illustrated by describing the proceedings of an
individual of the species Epeira calopliylla. Preparatory to casting its integument, this spider
spins some strong lines in the vicinity of its snare, from which it suspends itself by the feet
and a filament proceeding from the spinners. After remaining for a short time in this
situation, the coriaceous covering of the cephalo-thorax gives way laterally, disuniting at the
insertion of the legs and falces; the line of separation pursues the same direction till it extends
to the abdomen, which is next disengaged; the extrication of the legs being the last and
greatest difficulty the spider has to overcome. As the suspensory filament connected with
the spinners of the exuviae is considerably shorter than the legs, and does not undergo any
sensible alteration in length, the abdomen, during the process of moulting, becomes gradually
deflected from its original horizontal direction till it assumes a vertical position nearly at right
angles with the cephalo-thorax. By this change of posture, attended with numerous
contortions of the body, and alternate contractions and extensions of the limbs, the spider is
ultimately enabled to accomplish its purpose. When it has completely disengaged itself from
the slough, it .remains for a short period in a state of great exhaustion, suspended solely by a
thread from the spinners connected with the interior of the abdominal portion of the cast
skin, which is much corrugated. After reposing a little, the spider further attaches itself to
the suspensory lines by the claws of the feet, and when its strength is sufficiently restored,
and its limbs have acquired the requisite degree of firmness, it ascends its filaments and seeks
its retreat.1 .
Recent investigations have established the fact that the number of times spiders change
their integument before they become adult is not uniformly the same as regards every species,
Epeira calopliylla having been observed to moult five times, and Tegenaria civilis nine times,
from the period of their extrication from the egg till they arrived at maturity, and young
spiders infested by the larva of Polyspliincta carbonaria, an insect belonging to the family
IchneumonidtB, which feeds upon their fluids, never moult.2
Like animals of the class Crustacea, spiders possess the property of reproducing such
limbs as have been detached or mutilated, and this curious physiological phenomenon is
intimately connected with the renovation of the integument, for legs, palpi, and spinners, which
have been amputated are observed to be restored, and afterwards to have their dimensions
enlarged, at the period of moulting only.3
1 ‘ Transactions of the Linnean Society/ vol. xvi, pp. 482-484.
2 ‘ Report of the Fourteenth Meeting of the British Association for the Advancement of Science/
pp. 70, 71.
8 Ibid., pp. 71-74. '