Exuviation of Crustacea.
(THE PHENOMENA OF CRABS, ETC., CASTING THEIR SHELLS.)
'As Samson at his marriage propounded a riddle to his companions
to try their wits thereon, so God offereth such enigmas in Nature,
partly that men may make use of their admiring as well as of their
understanding; partly that philosophers may be taught their distance
betwixt themselves, who are but the lovers, and God, who is the giver
of wisdom.'--INTRODUCTION TO CONCHOLOGY, page 384.
VI.
The Armory of the Tower of London forms, it is generally admitted, one
of the most interesting sights of the great metropolis. No one can look
without wonder upon that goodly array of knights and noble warriors,
nor help an involuntary sigh over the degeneracy of modern humanity.
Though the figures before us are technically and irreverently termed
'dummies,' the hardened shell with which their body and limbs are
cased we know has felt the throb of many a true English heart, maybe,
glistened beneath the sun at Cressy and Agincourt, or perhaps on the
bloody fields of Worcester and Marston Moor. It requires no great
power of the imagination to transport ourselves to bygone centuries,
and listen to the ring of hostile arms, the sepulchral voices of men
whose heads are inurned in casques of steel, blended with the clash of
battle-axes, the whizz of arrows, the neighing of steeds, the rattle of
musketry, and at intervals the deep booming cannon's roar.
But, asks the gasping reader, what has this parade of mail-clad
warriors and old battle-fields to do with so prosaic a theme as the
exuviation of crabs? I must acknowledge that the question is a very
natural one, for there appears at first sight no connection between
the two subjects. The analogy will not, I believe, appear so forced
when I mention my possession of a smaller, although hardly less
singular armory, consisting of various coats of shelly mail, each of
which, at one time or other, belonged to, and was worn by a living
creature, and proved as effectual a protection in many fierce though
bloodless combats as any casque or helmet worn by knight. Unlike the
dummies of the Tower, my specimens are perfect, and give a complete
representation, more truthful than any photograph, of the defunct
originals, when armed by Nature _cap-a-pie_.
In plain words, I own a curious collection of the cast-off shells of
various crabs, which have from time to time been under my protection.
From the fact that no museum in the kingdom contains a single _series_
of such objects, exhibiting the various stages of growth in any
crustaceous animal, the reader will easily conceive the difficulty
there must be in procuring them, and consequently the interest that
attaches to the mysterious phenomenon of exuviation.
Strange to say, the subject of this chapter is one of the least known
in the whole range of natural history. The facts connected with the
process are few, and far from well authenticated. This state of things
appears the more extraordinary, when we remember the great facility
with which specimens of crustacea may be found.
For years past I have paid much attention to the elucidation of this
subject, and during that period have had to submit to numberless
mishaps and disappointments. For example, perhaps after watching a
'pet' day after day for months, anxiously expecting that exuviation
would take place, in nine cases out of ten,--ay, in ninety-nine out of
the hundred,--I would find that the process had been completed when
I was asleep, or that the animal had died suddenly. In the latter
case new specimens had to be procured, and the same watching process
repeated, in most cases with the like unhappy results.
I will now, however, endeavour as briefly as possible to make the
reader acquainted with what has already been written upon exuviation,
as far as I have been able to learn, up to the present time,
interspersing the narrative with such notes as may seem necessary by
way of illustration, and then proceed, in the words of Shakspeare, to
lay down my own 'penny of observation.'
The first clear and satisfactory remarks on this subject were made by
the celebrated Reaumur, who lived above a century ago: 'The unexampled
accuracy and truthfulness of this great naturalist is attested,' says
one writer, 'by the fact, that of all the observations made by himself
alone, far exceeding those of any other writer of past or present
times, and occupying in their published form numerous large quarto
volumes, scarcely one has been contravened by subsequent credible
observers, whilst they have formed the substance of half the numerous
compilations on insect life, acknowledged or otherwise, which have
appeared since his time.'
Goldsmith, who derived his knowledge of this subject from Reamur, tells
us, in his usual free and easy style, that crustaceous animals (as
crabs and lobsters) 'regularly once a year, and about the beginning of
May, cast their old shell, and nature supplies them with a new one.
Some days before this necessary change takes place, the animal ceases
to take its usual food. It then swells itself in an unusual manner,
and by this the shell begins to divide at its junctures between the
body and the tail. After this, by the same operation, it disengages
itself of every part one after the other, _each part of the joints
bursting longitudinally_, till the animal is at perfect liberty. _This
operation, however, is so violent and painful that many die under
it_; those which survive are feeble, and their naked muscles soft to
the touch, being covered with a thin membrane; but in less than two
days this membrane hardens in a surprising manner, and a new shell as
impenetrable as the former supplies the place of that laid aside.'
This, then, was and is to a great extent, up to the present time, the
universally adopted explanation. Goldie, of course, could not afford
time, and it may be doubted if he possessed the requisite amount of
patience, to confirm what he wrote by actual observation. Seeing that
the statement was graphic in its details, and evidently either wholly
or in part the result of personal observation, he very naturally
gave it full credence. But what shall we say of a noted writer (Sir
C. Bell)[4] who apparently half doubts the truth of exuviation, for
although he mentions the particular account which Reamur gives, yet
tells his readers that '_naturalists have not found these cast off
shells_.' After such a remark as this, we need no longer sneer at the
compilations of the author of the 'Vicar of Wakefield.'
[4] Illustrations to Paley's Natural Theology.
I need hardly state, that at certain seasons of the year almost every
rock-pool at the sea-shore will exhibit to the observant eye scores of
'these cast off shells' in a perfect state. The writer above quoted
also remarks, 'We presume the reason that the shells of the crustacea
are not found in our museums, is because they are not thrown off at
once, but that the portions are detached in succession.' An ill-founded
presumption this, the fact being that the inelastic integument is
invariably (in all the Decapoda at least) thrown off entire, the eyes
and long antennæ sheaths, the claws with the hair attached, even the
gastric teeth, all remain with wonderful exactness.
To look at the rejected shell, indeed, any person not previously
acquainted with the fact would naturally suppose that he saw before him
the living animal, a close inspection being necessary to dispel the
illusion. As soon as the crab has emerged from its old covering, it
increases with such astounding rapidity, that at the end of one or two
days it can grow no larger until the next moulting time.
In referring to my own introduction to the subject of exuviation, I may
be allowed to notice the annoyance a young aquarian experiences from
the rapidity with which the tank water is apt to become opaque. As such
a state involves considerable trouble, especially when the occupants of
the tank are the subjects of continued observation, I may mention, in
passing, that the means I adopted to correct this state of matters was
either to syringe the water frequently, or what seemed to answer still
better, to permit it to run off by a syphon into a basin on the floor.
When the opacity of the tank is occasioned by decaying animal matter,
the only remedy is to remove the offending 'remains.' But with many of
the common inhabitants of the tank--the crustaceans, for example--great
difficulty is often experienced in ascertaining their state of health,
with a view to sanitary investigation. As these creatures, instead
of boldly exhibiting themselves during the day, generally hide under
pebbles or pieces of rock, or are buried in the sand, it is sometimes
necessary to submit the contents of the mimic rock-pool to a process
of 'putting things to rights,' as the ladies say when about doing a
kindness,--oh, horror!--to our books and papers.
It happened on a certain occasion that my aquarium was in an
unsatisfactory condition. A nasty vapour arose from the base, and
diffused itself over nearly the entire vessel. My fishes disliking
their usual haunts, were all spread out at full length high and dry
upon a ledge of rock-work, projecting above the surface of the water.
The little Soldier-Crab had managed to drag his body and heavy tail
piece up the brae, hoping to breathe the fresh air in safety. His big
brother was not so successful, and despite his efforts speedily came to
grief. Finding he could not drag his carriage up the rock, he stepped
out of the lumbering vehicle. His appearance soon became woe-begone
in the extreme. In a few minutes he expired. The buckies, too, with
singular instinct, had collected in a row along the dry ledge of the
tank.
Upon counting the numbers of my little colony, I found all right,
excepting _C. mænas_; him I could not discover, and I soon began to
suspect that he was defunct. No time, therefore, was to be lost,
so a diligent search for his remains was instantly commenced.
Fishes, Buckies, Hermits, &c., were speedily placed in safety in
an extemporaneous tank--nothing else than an old pie-dish. This
receptacle, when partly filled with sea-water, admirably answered the
required purpose.
The water in the large vase was gently run off, and on approaching
the base I found, as I expected, the dismembered carcase of the
crab. One leg lay here, and another there, while the body was snugly
esconced beneath a stone, on which sat my favourite limpet with
its curiously formed shell, profusely decorated with a plume of
sea-grass and infantile _D. sanguinea_. Here, then, I thought, was
the mystery explained. It was from this spot that the noxious vapour
must have emanated. Of course, the body of the crab was removed; but
in performing this necessary act I tilted the stone, and so disturbed
the Limpet. Guess my surprise at observing the overturned shell of the
Patella to be quite empty, and its former occupant lying before me a
mass of putrefaction.[5] It now began to dawn upon me that I must have
libelled _C. mænas_. A few moments served to confirm this opinion, for
on lifting the stone, there darted out _a_--I could scarcely believe it
was _the_ crab, who instantly went through a circus-like performance
around the circumference of the vessel.
[5] This affords an important hint to the young aquarian to watch the
Patella, and occasionally to touch its conical house, to make sure the
proprietor is alive and well.
The reader will be prepared to learn that what I had at first observed
were portions of the exuvium, which had by some means been distributed
over the tank.
Many months did I wait with nervous anxiety to see the exact process of
exuviation, but, except in the instances I am now about to chronicle,
my wishes were never gratified.
I had at one time in my possession six little vases, each containing a
crab measuring about one inch across the back (_carapace_). By constant
watchfulness, morning and evening, for several months, I naturally
entertained a confident hope of being favoured with a sight of the
moulting operation in at least a single instance. But no; persevering
though my endeavours were, I was always disappointed. The exuviæ were
cast regularly enough, but the crabs so managed matters, that the
process was completed either when I was asleep, or had just gone away.
I could almost have sworn that the whole pack had entered into a league
to annoy me.
On one occasion I sat up all night, feeling confident, from symptoms
which a certain Cancer mænas exhibited, that he was speedily about to
exuviate. Alas! I was mistaken. On my endeavouring to expedite the
event by lifting up the carapace of the crab, I received a nip on my
finger so severe, that I shall never forget it.
But at length in the early portion of last year (1859), I, most
happily for my own peace of mind, did actually witness the entire
process of exuviation in a tolerably large specimen of the Common Shore
Crab. The animal in question, who was domiciled in a crystal vase,
or, in common language, a glass tumbler, rendered himself a favourite
from his constant habit of poking part of his head and his entire
claw (he had got but one), out of the water whenever he caught sight
of me. Who could resist such a powerful, though silent appeal to 'the
generous impulses of one's nature' as this? Certainly I could not,
and therefore, once a day at least, gave Master Cancer the half of a
newly-opened mussel, a tit-bit that was greatly relished. He would
sometimes get a grip of the valve, and allow himself and the Mytilus
to be entirely raised out of the water. Improving upon this, he would
then partly finish his meal while seated in my hand. On the morning
of the above mentioned eventful day, I gave the crab a portion of a
Pholas, but to my surprise, the heretofore high-class dainty remained
untouched. I was in ecstasies! for I felt morally certain that the
grand event, so long looked for, was soon to take place. Consequently,
I took out the crab, cleaned the windows of his dwelling in order
that I might the better see what was going on within, treated him to
some fresh water, as well as a new frond of sea-weed, and then again
introduced my pet to his old apartment.
Before doing this I had the animal closely examined, to see if any
signs of the approaching moult could be detected, but none were
visible, except that the glassy bags, if I may so call them, which for
some weeks had been gradually thrown out from the stumps of the three
mutilated limbs, appeared finer in texture than usual. Indeed, so
transparent had they become, that I could distinctly see the contour of
the new limb about to be reproduced, folded up within each capsule.
A few minutes after the crab had been placed in the tumbler, I gave a
peep to see how he was getting on. To my intense surprise, I observed
that his shell had just opened near the tail! My first feeling was
one of sorrow, thinking that in handling the specimen I had been too
rough, and had perhaps injured it. This apprehension was soon changed
to delight, as I became by degrees aware that exuviation had actually
commenced.
The operation did not extend beyond five minutes (although the time
appeared much longer to me), and was carried on by gentle, and at first
almost imperceptible degrees. The shell, or carapace, was slowly raised
over the back, and gave one the idea of the rear view of a lawyer's
white wig when tilted over his brow, thus exposing the natural black
hair on the occiput below; for, as the body of the animal came forth,
it was very dark in colour, while the old case assumed a whitish hue.
I need hardly say, the leg sheaths of the crab did _not_ split open,
and yet the corresponding limbs were drawn out with the greatest ease.
Moreover, they did not appear in view one by one, but in a cluster, as
it were, and packed close to the bent body of the crab.
During the entire process the animal appeared to use scarcely any
exertion whatever, certainly not half so much as any human being would
exhibit in throwing off the most trifling garment. In fact, the crab
seemed to swell painlessly, and gently roll or glide out in a kind
of ball. Until it had completely escaped from its old shell, I was
somewhat puzzled to guess what shape it would eventually assume. The
eyes and antennæ, so soon as they left their old sheaths, commenced,
together with the flabellæ, to work as usual, although as yet they were
still inside the exuvium. This circumstance was distinctly visible by
looking through the side of the half-cast shell.
It was a curious and extraordinary sight to see the eyes gradually lose
their brilliancy, and exhibit the filmy, lack-lustre-like appearance of
death, while the act of exuviation was being accomplished. I may add
that the tumbler which held my little captive stood upon a table near
a large window, and that the sloughing operation was watched through a
powerful hand lens.
On an after and well-remembered occasion, I saw a moderate-sized
Partane standing on the top of a bush of _Chondrus Crispus_ that grew
in my aquarium. The fronds were attached to a piece of sandstone,
placed uppermost upon a cluster of rock-work, situated, as before
mentioned, in the centre of the vessel, and rising slightly above the
level of the water. Thinking he was planning means of escape, I turned
away for a few moments to procure a simple instrument wherewith to
carry him to a less elevated position. On my return I saw him in the
act of backing out of his shell. It was a singular circumstance that
I should have just risen from the perusal of a talented author, who
informed me that 'the crab hitches one of its claws into some crack or
fissure, and from this point of resistance gives more power in emerging
and withdrawing itself from between the carapace and the tail.'
Certainly no statement could more inadequately describe what I had
witnessed in both of my crabs. Not only was the whole operation
performed with perfect ease, but I am much inclined to believe with a
degree of pleasure. For a while one of my crabs stood in juxtaposition
to the shadow of its former self, and rubbed his antennæ and wee
peeping eyes as if awakening from a sleep. He had been lately, there
was no doubt, living in an oppressed state, and might probably have
surveyed things around him somewhat darkly, but now all was bright and
clear again. On turning, the first object that caught his awakened
eye was his cast-off vestment, which he seemed to scan as dubiously
as a grown man would an exhumed pair of boyish corduroys, and mutter
musingly, while stroking his chin, 'Well, come what will, it can never
be my _case_ again.'
On taking it in my hand, the Partane felt quite soft and velvetty to
the touch, and exhibited no signs of alarm.
Since then I have repeatedly had shells of crabs cast _in smooth glass
globes, containing nothing else but clear salt water_. This fact, in
my opinion, completely subverts the statements of certain writers, who
assert that these animals require extraneous assistance when about to
exuviate.
Some writers have questioned the truth of the generally-received
opinion that the new parts of the crab are derived from the old: that,
for instance, a claw is regenerated within a claw, a limb within a
limb, eyes within the eyes, and that on exuviation each is withdrawn
from the pre-existing organ as from a sheath. But my operations tend
fully to confirm the popular and existing belief.
There is yet one curious point connected with this subject which
requires explanation, as it is not generally understood. I allude to
the apparent disproportionate smallness of the 'glassy bag,' situated
at the stump, as compared with the size of the regenerated limb, which
is supposed to be folded up within the bag previous to exuviation.
On looking at the newly-formed member, we can scarcely believe it
possible that the transparent case could by any possibility have held
it. The mystery vanishes if the new limb or claw be examined; for,
although in shape it is perfect, even to the most minute particular, it
remains for a certain period comparatively useless to the animal, from
the fact of its being utterly devoid of flesh.
The new limb, therefore, can be considered merely as an expanded case,
which, by a wonderful law of nature, becomes slowly filled up and
completed. Immediately after exuviation has taken place, and a claw is
introduced in the place of some mutilated stump, if any one will pull
off the new member, he can readily confirm the truth of what I have
stated, and, moreover, be able to test into how very small bulk the new
limb may be rolled.
As the reader may remember, Goldsmith states that the crab casts its
shell 'regularly once a-year, at the beginning of May.' Professor
Owen fixes the date in the month of August. Professor Bell states,
that 'there is no doubt exuviation takes place _annually_ with great
regularity, until the growth is completed, which, in many species, is
not before the animal is many years old.' Another professor, treating
on the same subject, thus writes, 'We are told that all this coat
of mail is _annually_ thrown off in a single piece by the contained
animal,--the great proficient in Chinese puzzles may well be posed at
this greater puzzle.' In fact, all writers whose works I have had
opportunity of examining repeat the statement. Mr. Ball, who writes
from personal observation, apparently confirms beyond a doubt, the
annual moult of Crustacea. This gentleman, we learn, kept a Cray-fish
alive for two years in a vase, and found that _during each year its
exuvium was shed but once_.
It may readily be believed, with such a formidable array of contrary
evidence, that I offer my own observations with modesty. But at the
same time, I feel justified in confidently stating that the moult of
the crab, (in its comparatively youthful state, at all events), takes
place not only once, but many times during each year of its existence.
My specimens may, perhaps, be considered exceptions to the general
rule, but the facts I relate cannot by any possibility admit of doubt.
The cast-off shells lie before me as I write.
Here is a set of three belonging to the same animal, exhibiting with
marvellous exactness the gradual development of a broken claw. In the
first the member appears very diminutive, in the second it is nearly
twice its size, while in the third it has advanced to its natural form
and bulk. To my regret, I cannot state the exact period that elapsed
between each successive moult, but I am confident that the trio were
cast in the course of a very few months.
I may here take the liberty of informing the uninitiated, that the
appearance of the above objects is extremely pleasing; for, as the
exuvium becomes dry, its colour changes to a bright scarlet, somewhat
resembling that which the crab assumes when placed for a time in
boiling water.
The next series of specimens, five in number, possess even still
greater interest than the first examples. They were produced by a
youthful _C. mænas_, at the following consecutive intervals:--
The first moult took place on 11th April 1858; the second on the 22d
of May following; the third on July the 3d; the fourth on the 30th of
August; and the fifth on the 26th of September in the same year. So
that between the first and second period of exuviation there was an
interval of forty-one days, between the second and third forty-two days
elapsed, between the third and fourth fifty-eight days, but, singular
to state, between the fourth and fifth moult _only twenty-seven days
intervened_.
My first impression was, that as the creature grew older, its shell
would be renewed less frequently, and the dates of the sloughings
seemed to support this idea--until the fourth moult. It had occurred
to me that perhaps the operation might be accelerated by the amount
of diet which the crab consumed. In order to test this, I fed the
animal carefully every day, as though he were a prize beast about to be
exhibited at some Christmas show. Nothing loath, he ate of everything
that was placed before him with a gusto that would have done credit to
an alderman. The result was, that the shell was renewed in less than
half the time that elapsed between the preceding moults.
These interesting investigations, which had been conducted thus far so
satisfactorily, were suddenly brought to a close by the death of my
protégé. This sad event occurred unexpectedly, not from overfeeding, as
some persons may suppose, but from natural causes.
Whether increase of food always produces a like effect to that
mentioned, is a point that I hope some of my brother naturalists will
be able to determine. That the moult was accelerated by such means
in my own specimen I have not the slightest doubt, for, on no other
grounds can I explain its unusually speedy occurrence.
I may here assure my readers that the above dates may be confidently
relied upon as correct, and also that each exuvium was produced by the
same crab--one specimen only being in the tank during the whole period.
Since the foregoing was written, I have again been fortunate enough to
have ocular demonstration of the phenomenon of exuviation, as occurring
in a _Cancer Pagurus_, about as large as a moderate-sized walnut.
While watching this crab, it flashed across my mind that it would be a
happy circumstance if by any means _I could arrest the process then
going on before my eyes, while it was yet only half completed_, in
order that others might also be enabled to witness the marvellous act
of exuviation.
But how to carry out this scheme was the rub. I knew that--
'If 'twere done, then 'twere well it were done quickly.'
One minute passed,--two minutes flew by;--the crab would speedily
complete his labours; still was I perplexed.
To plump it into fresh water would, I knew, be fatal to the animal,
but not in such a speedy manner as was desirable. Boiling water next
suggested itself, and doubtless would have answered the purpose
effectually, had a supply been near at hand at the time, but such was
not the case. I then thought of _spirits_. Ah! capital idea.... Before
the third minute had passed, I might be seen to rush frantically to the
sideboard, pour _something_ into a glass, then dart back to the tank,
dive down my trembling hand, bring up the poor unfortunate crab, and
drop it into a fatal pool of pure "Glenlivet."
The animal appeared to die quickly, and was next day transferred to a
vessel filled with Mythilated spirits. As it luckily turned out, the
whisky answered the intended purpose remarkably well.
The preparation in question is, as far as I can discover, _unique_; at
least I have neither read nor heard of another such existing in any
private or public museum in the kingdom.[6]
[6] A drawing of this crab will be found on Plate 3.
It shows at a glance the increase that instantaneously takes place
in the size of the crab after the act of exuviation is performed,
the portion exuded being on a scale considerably larger than the old
covering, which, however, is capacious enough to hold that half of the
animal that had not effected its deliverance at the moment when the
novel arrestment was so unceremoniously served.
The fourth and fifth pair of legs are free, while the eyes and antennæ
are also drawn out of their sheaths. (This is not very evident now,
but such is really the fact, I having distinctly seen those organs
in motion when the animal was in the living state.) The _chelæ_, or
large claws, being still undetached, serve to bind the crab to its old
integument, and thus enable the act of exuviation, or one phase of it
at least, to be distinctly apparent.
I know of no work on Natural History that speaks of the Hermit-Crabs
(_Anomoura_) casting their shells, and on this account I have given
some attention to them. These animals being so common, I kept by me at
least a dozen specimens for the purpose of observing some of them, if
possible, in the act of exuviation. The result of my labours has not
been so satisfactory as I could wish, from my not having been able to
collect any 'sets' of exuviæ. I cannot, therefore, speak with certainty
as to the frequency of this phenomena. By this time my readers will
know that the tail of the Hermit-Crab is very tender and fleshy, being
covered merely with an extremely delicate membraneous skin, while the
carapace, claws, and antennæ of the animal are protected by a hard
crust, similar to the Lobster, Cray-fish, &c.
From this peculiar formation of the crab, I was not at all surprised to
find, on several occasions, the upper part of its body alone cast off,
and therefore came to the very natural conclusion, that as the tail was
soft, it would grow and increase in proportion to the other parts of
the animal, without ever needing the skin to be changed.
Each morning and evening during the time my experiments were being
conducted, I examined all the tanks attentively, to see whether an
exuvium had been cast. If visible, the object was picked out and gummed
in a box, and a date placed above it for future reference. After
having performed an operation of this kind one afternoon in October
1858, I saw a Hermit-Crab (who had cast his shell on the previous
day) hurriedly leave his testaceous dwelling, then scrape away at his
tail, and after a moment's interval, leap into his old seat again. On
inspection, I found to my surprise _that he had actually_ _slipped off
the skin of his tail_![7] much in the same fashion as we would draw off
a well-fitting glove. Here was a strange and unexpected discovery.
[7] The fact of the exuvium of the Hermit-Crab being cast off in two
pieces, and at different periods, I have since confirmed 'many a time,
and oft.'
On submitting the exuvium to the microscope, we find that the covering
of the false feet, and the cilia attached to the same, all remained
fixed in their natural position to the tail-piece. Although in several
cases I have had no difficulty in discovering the rejected cuticle of
the tail, at other times it has eluded my search. The cause of this
I cannot explain. It may be that the animal, adopting the habits of
the toad, swallows a portion of its exuviæ as soon as cast. On two
occasions I found the slough of the body and claws of a crab, and
waited patiently for several days, without success, expecting to get
the tail portion. Growing impatient, it occurred to me that it would be
a curious experiment to try and draw off the exuvium with my fingers.
This was easy to talk about, but difficult to perform.
In the first place, the crab would not, if he could help it, allow
himself to be handled even in the most gentle manner. To overcome
this difficulty the shell had to be broken. This was done; but, alas!
the shock nearly killed the poor little Hermit. After some trouble,
I carefully unwound his body from the whirls of the Top Shell, and
proceeded to perform the intended operation. Reader, have you
ever seen a child take a rose-bud in his hands, and force open its
half-pouting blossom, in the belief that by so doing he was assisting
nature? If so, you must have watched the puzzled expression of the
boy's countenance when he beheld the leaves fall one by one at his
feet, and the bud itself exhibit evident signs of approaching decay.
In just such a position did I stand with regard to the poor
Hermit-Crab, for, in spite of all my care in manipulation, the skin
of the animal was so tender and delicate that the first gentle pinch
caused a puncture which proved fatal; and as to drawing off the
covering, the thing I now believe to be impossible, even under the most
favourable circumstances.
The upper portion of the Soldier-Crab, I may mention, is cast off in
one piece, while the animal is seated in its turbinated dwelling. The
act is performed with the most perfect ease. Unlike the _Brachyura_,
the _Anomoura_ do not exhibit signs of such rapid growth immediately
after exuviation, but increase in size very gradually indeed.