Ants, to call attention to the principal questions which still await
solution. The first is one which any observer who travels in Central
Europe during the summer may help to solve.
1. Do _any_ ants collect and store seed in Switzerland, Germany,
North France, England, or indeed in any of the colder parts of the
world?
2. What are the habits of _Atta structor_ and _A. barbara_ when
living, as they are known to do, in Switzerland, Germany, and
Northern France?
3. How do the ants contrive to preserve the seeds in their granaries
free from germination and decay?
4. How are the seed-stores of tropical ants disposed below ground,
and of what do they consist?
5. Do harvesting ants exist in the southern states of North America,
in Australia, New Zealand, or at the Cape?
SUPPLEMENT
TO
TRAP-DOOR SPIDERS.
There would doubtless be a just feeling of pride and satisfaction
in the heart of a naturalist who could say that he had made himself
thoroughly acquainted with all the species of a particular group of
animals, had learned their most secret habits, and mastered their
several relations to the objects, animate and inanimate, which
surrounded them. But perhaps a still keener pleasure is enjoyed by
one who carries about with him some problem of the kind but partially
solved, and who, holding in his hand the clue which shall guide him
onwards, sees in each new place that he visits fresh opportunities of
discovery. The latter is certainly the condition of those who take
an interest in searching out the habits and characters of trap-door
spiders; for this subject, far from being exhausted, expands under
the light of recently acquired facts, and invites research in many
parts of Europe, north as well as south.
We have only to compare the number of types of trap-door nest which
were known before the publication of _Ants and Spiders_, with those
at present recorded, to see how fruitful this field of inquiry has
already proved.
Before this little work was published, only one type of trap-door
nest was known in Europe: two new types were described in its pages,
and I have now the pleasure of being able to bring three more
hitherto unknown European types before the notice of my readers, thus
raising the number to six in all. I do not include in these six types
the very curious, and still imperfectly-known nest of _Atypus_;[122]
a spider which is a true representative of the trap-door group as
far as its structural characters are concerned, but which, although
it excavates a silk-lined burrow in the earth, does not appear to
construct any kind of door at the mouth of its tube.
[Footnote 122: See _Ants and Spiders_, page 78. _Atypus_ belongs to
the sub-family _Atypinæ_, a division which does not include any of
the _Nemesias_ or _Ctenizas_, and of which indeed _Atypus_ is the
only European representative.]
Much uncertainty still hangs over the habits of this spider, as the
facts hitherto recorded, though perfectly authentic, are difficult
to piece together into a satisfactory whole. One thing, however,
is clear, and that is, that the nests and habits of the spiders of
the genus _Atypus_ (of which, as Mr. Pickard-Cambridge, informs me,
two if not three distinct species inhabit England) merit attentive
study, and would most certainly repay it. Hastings, Portland, the
coast of Dorsetshire, and the neighbourhood of London and Exeter, are
the habitats hitherto cited for this spider, but I cannot doubt its
existence in many sheltered localities on the south coast of England.
The most recent contribution to our knowledge of this genus is
contained in a paper by M. Eugène Simon,[123] who describes three
species (two of which are new), as inhabiting France, and it remains
to be ascertained whether our British _Atypi_ agree in their
characters with any of these.
[Footnote 123: Note sur les Espèces françaises du genre _Atypus_,
Latr. in Ann. Soc. Entomologique de France, 5^e ser. tom. iii.
(1873), p. 109.]
He describes (p. 113-4) the nest and mode of life of _Atypus piceus_,
Sulzer (=_A. Sulzeri_, Latr.),[124] the commonest of the three
species, as follows:--"They (the spiders) seek dry and somewhat sandy
slopes, sometimes also woods, chiefly plantations of evergreens;
their retreat is always concealed either by stones, or in moss which
one must remove carefully and in large masses (_plâques_) in order to
detect them."
[Footnote 124: Thus named by M. Simon.]
"This Atypus excavates an oblique hole of 15 to 20 centimetres deep,
and of the size of its body; it lines it with a rather narrow silken
tube of a very close texture, the upper part of which, exceeding the
subterranean portion in length, lies horizontally on the surface
of the ground, and ends in an open tapering point. Near its lower
extremity the tube is suddenly contracted, and then dilates into
the form of a fairly spacious apartment, in which the spider lives;
the cocoon enclosing the eggs is suspended by a few threads at the
contraction. I have frequently surprised _Atypus_ in the act of
holding earth-worms in their falces, and I think that these Annelids
constitute the larger part of their food; indeed, if one examines
the lower portion of the silk chamber, one may remark a part where
the tissue is thinner and more transparent. I have not been able to
detect an opening, but it is probable that the _Atypus_ can easily
part the not very compact threads, and thus obtain for itself an easy
prey, and dispense with the necessity of ascending to the surface
of the ground. When taken out of its tube, _Atypus_ does not even
attempt to escape; it is therefore plain that it is not organized
for the pursuit of an active prey; and, on the other hand, the upper
extremity of the tube is ill-adapted for an ambuscade, being almost
closed, and without support. This small opening would seem to be
solely intended for the entrance and exit of the male (a very much
smaller creature than the female) during the breeding season, which
occurs in the month of October."
[Illustration: _Plate XIII_]
M. Simon says that this species of _Atypus_ is common in all the
centre, east and west of France, and that he has detected it in
great abundance in the neighbourhood of Troyes, in Champagne, in the
month of October, when the male was inhabiting the same tube with
the female.[125] I am greatly indebted to M. Simon for having given
me the specimen of a silk tube taken entire from a nest found in
this locality, which I have figured in Plate XIII., fig. A. It will
be seen that the tube has collapsed, but one may still trace the
enlargement near the base which forms the chamber, the elbow where it
is bent at the surface of the ground, the moss, scales, and fibres
of plants which are woven into, and serve to conceal the aërial
portion, and its termination in a twisted and apparently-closed mouth.
[Footnote 125: M. Simon has discovered another species of _Atypus_ at
Digne in the Basses Alpes which constructs a similar nest to that
described above. This species was detected for the first time by M.
Simon and described by him under the name of _Atypus bleodonticus_.]
Indeed, I believe that, in this specimen, the upper extremity of the
tube is really closed, for, when I succeeded in inflating this aërial
portion, the lips did not part, but remained drawn together.
It seems very extraordinary that the mouth of the tube should be thus
closed, so that the female spider becomes a prisoner, self-immured,
and I can only suppose that this is a temporary condition, limited
perhaps to the period during which she receives the visits of the
male.
At the very base of the tube I found a mass of earth, roots and
vegetable fibres, and in this I hoped to have detected the _débris_
of insects or other food, such as I sometimes find at the bottom of
and below the tubes of the trap-door nests in the South, but of this
there was no trace.
It is difficult to me to imagine how the spider could contrive to
live by the capture of worms, after the fashion suggested by M.
Simon; for who does not know the speed with which, on the slightest
alarm, worms draw back into their holes and escape pursuit, and the
muscular power which they exert in resisting any attempts to drag
them out of the earth?
M. Simon's account of the closed tube and capture of worms by this
spider corresponds, however, with that given by Mr. Joshua Brown, the
first discoverer of _Atypus_ in England.
This gentleman communicated his discovery to Mr. Edward Newman[126]
in 1856, since which time (with the exception of M. Simon's paper
quoted above) little or nothing seems to have been done to clear up
the points which remain doubtful in the history of these singular
creatures.
[Footnote 126: Note on _Atypus Sulzeri_ of Latreille, by Mr.
Edward Newman, read before the Linnean Society; a report of this
communication is given in _The Zoologist_, vol. xiv. (1856), p. 5021.]
Several nests of _Atypus_ were discovered by Mr. Joshua Brown in the
neighbourhood of Hastings, when traversing a lane bounded on either
side by high and steep sand-banks, partially covered with grass and
bushes.
His attention was at first arrested by the sight of "something
hanging down which looked like the cocoon of some moth;" but, on
closer examination, the silk case proved to be empty, and was
continued as a tube into the ground to a depth of 9 inches, where he
came upon the spider lying at the bottom. Further research revealed
the existence of a number of these nests in the same locality, but
the length of the different tubes varied much; they were usually
about 9 inches long, but some were much longer, often baffling his
attempts to follow them; the longest which he was able to secure
entire measured 11 inches. All the nests were, however, alike in
having a tubular silk lining, about 3/4 of an inch in diameter, a
part of which protruded from the ground for about 2 inches, and was
pendent, inflated, and covered with particles of sand, assimilating
it to the surrounding surface; it was closed at the upper extremity,
leaving no exit to the open air.
Mr. Brown took home some of these tubes in a collapsed state with
the spider at the bottom. In one case, on opening the box in which
the nest was placed, he perceived a movement throughout the tube,
as if it were being inflated; this however soon subsided, but the
following morning he was surprised to see that the whole tube was
inflated, especially at the end which had lain exposed on the bank.
He failed to find any aperture by which the spider could enter or
leave her nest, and his captives, though passing backwards and
forwards in their tubes, never came out at either end. He never saw
flies or any fragments of insects in the nests; but, on drawing out
one of the tubes, he observed a worm at the lower end, partially
within it, partially outside, and he perceived that the spider
had evidently been eating a considerable portion of its anterior
extremity.
It will readily be seen that there are some discrepancies between the
different accounts which have been given of the nests of _Atypus_
found in England and France,[127] and I think it quite probable that
some at least of the nests described may really differ, and be the
work of distinct species belonging to this genus. Mr. Brown describes
his nests as having by far the greater part of their length under
ground, while in those observed by M. Simon, as shown in my figure,
Plate XIII. fig. A, the exposed portion of the tube equalled or
exceeded the subterranean.
[Footnote 127: A subject already alluded to in _Ants and Spiders_, at
p. 78.]
An imperfect specimen at the British Museum, from some English
station (exact habitat not given), appears to have the proportions
described by Mr. Brown; the length of the aërial portion of the tube
being less than one-fourth of that of the subterranean; the upper
end of the tube is however open, but I am doubtful whether this was
originally so or not, for the silk is torn at this point, and the
opening may be a rent caused by rough handling.
After a comparison of the above description, it appears to me that
the following are the principal points which remain to be cleared up:
1. What is the precise structure of the nests of Atypus, and are they
always uniform in character at all seasons of the year?
2. What is the use of the exposed aërial portion of the tube?
3. Do the two British species make similar nests?
4. What food, besides worms, does the female live upon, and how does
she obtain it?
5. Does she ever leave the nest?
6. What becomes of these spiders and their nests in the winter, and
how long do they live?
7. When do the young leave the nest; and do they, like their
relatives in the South, construct nests like those of their parents
in miniature?
I would commend all these points to any lover of Nature who may
seek the southern coasts of England during the autumn and winter
months, and I think it more than likely that a careful search in
the sandy banks near St. Leonards, the slopes under the fir-woods
of Bournemouth, and the deep lanes in the neighbourhood of Torquay,
would be rewarded with success.
If the breeding season in England only commences in October, as
appears to be the case in France, it would seem most probable that
the spiders survive the winter. Very possibly these spiders and
their nests might be transplanted and placed for observation in a
garden; and if room were granted them in a greenhouse or Wardian
case, or even in a large flower-pot in a living-room, it is not
unlikely that the warmer temperature might waken them up to renewed
activity.
It seems clear that _Atypus_ has to fear the insidious attacks of
enemies; for not only is the external portion of the tube closed or
almost closed at certain seasons, but it is covered outside with such
materials as may serve to make it resemble the surrounding surface
of the ground. Thus Mr. Brown's nests, lying on a sandy bank, were
covered with particles of sand, while my specimen from Troyes has
moss and fibres of plants woven into its upper extremity.
Indeed, all the European representatives of the suborder
_Territelariæ_ which I have myself met with, conceal their nests
with great care and skill. There appear to be others, however, which
either make no nests at all but hide under stones, or only construct
a simple silk tube, open at the mouth, and without any special
contrivance for its dissimulation. Further observation of the habits
and dwellings of these apparently unworthy members of the trap-door
group is much to be desired.
Mr. Bates,[128] in his work on the Amazons, describes _Mygale
(Theraphosa) Blondii_, a large and powerful spider of that region, as
burrowing into the earth and "forming a broad slanting gallery about
three feet long, the sides of which he lines beautifully with silk."
This spider "is nocturnal in his habits," and maybe seen "just before
sunset keeping watch within the mouth of his tunnel, disappearing
suddenly when he hears a heavy foot-tread near his hiding place."
[Footnote 128: Bates, H. W., _Naturalist on the Amazons_, Ed. 2.
(1864).]
This nest would therefore appear to have an open tube undefended
by any door; but in this case the great size of the spider and the
depth of the burrow, which is more than twice as long as that of the
average European nests, may help to explain this apparent want of
precaution.
But, if we wish to learn with what different materials and by what
varied means the same end of self-preservation can be attained, we
have only to cast a glance at the sketch of a portion of a nest at
fig. B, Plate XIII., p. 183, where it will be seen that the entrance
to the nest, far from being concealed or obscured in any way, is
rendered a most striking object, and one which appears devised
for the very purpose of attracting attention. The nest to which I
refer is the work of _Cyrtauchenius elongatus_, from Morocco, and
consists, according to the account given me by its discoverer, M.
Simon, of a deep cylindrical burrow in the soil, the silk lining of
which is prolonged upwards for about three inches above the surface
of the ground, and enlarged into a funnel shape, so that it becomes
from two to three inches across at the orifice. This aërial portion
being snow-white, at once attracts the eye even from a considerable
distance, and the nests rising up amid the sparse grasses and other
small plants which serve to support but not to conceal them, present
the appearance of scattered white fungi.
This is therefore quite a new type among the nests constructed by
trap-door spiders, new in form and probably in function also, and I
would propose to distinguish it provisionally as the _funnel type_.
Now the female _Cyrtauchenius_ is, like its near relatives the
_Nemesias_, a sluggish and rather helpless creature, and shows no
apparent physical superiority which might countenance its dispensing
with the methods of concealment which form the characteristic habit
of the group.
How then does this spider manage to escape its many enemies,
especially the insidious attacks of the insects of the _Sphex_ and
_Ichneumon_ families, which certainly abound in Morocco?
Mr. Wallace, to whom I put the question, suggested that this species
may perhaps be chiefly nocturnal in its habits, and that, if this
is the case, the bright white and flower-like tube of the nest may
possibly serve to attract night flying insects, which would thus
become its prey.
In any case, whether we can discover them or not, some curious points
of difference must exist between this spider and its allies, which
secure to it a comparative immunity.
It appears to me that there are few questions which can be of greater
interest to the naturalist than those which have to do with the
conditions determining the existence of a given species in a given
place.
Of the questions, Who are your relatives? Where do they live? and How
are you able to live here? surely the last is not the least important.
And, if we wish to try to answer this question, we must do all in
our power to find out how the habits and conditions of life of the
creature in question, differ from those of its competitors; for we
may be quite certain that it does not exist where we see it by grace
and favour, but by merit; if it is neither stronger, cleverer nor
more numerous than its neighbours, we may be sure that it has found
some means of living which does not interfere fatally with their
requirements. Hence the endless diversity of function and habits in
all living creatures, which forms such a prolific and marvellous
subject for our study and contemplation.
I am indebted to M. Simon for permission to publish the details given
above on _Cyrtauchenius elongatus_, and also for having given me such
directions as enabled me to make the sketch from which the drawing at
Plate XIII., fig. B, was copied.
I must however state that this illustration is not taken from an
actual specimen, but is prepared solely from his description; so that
it cannot pretend to complete accuracy of detail. M. Simon assured
me nevertheless that it conveyed the general appearance of this
remarkable nest with sufficient fidelity, and I have been induced to
reproduce it here in the hope that it may serve to make my meaning
plainer, and to suggest the kind of object which one should look for,
if an opportunity offered.
Another species of the same genus, _Cyrtauchenius Doleschallii_, is
known to inhabit Sicily, but the nest is undescribed. M. Lucas has
described two species,[129] belonging to the closely-allied genus
_Cyrtocephalus_, both of which appear to construct nests somewhat
similar in form to that discovered by M. Simon. Whether these
nests are equally showy we cannot tell, as the account is brief and
few details are given; but one, that of _Cyrtocephalus terricola_,
appears to differ in having threads stretched from the opening of its
funnel, which serve to ensnare insects and to give notice of these
captures.
[Footnote 129: _Cyrtocephalus Walckenaëri_ and _terricola_, Lucas
(H.), _Animaux articulés de l'Algérie_ (Paris, 1847-9), vol. i. p.
94-5.]
The great trap-door group therefore comprises spiders which differ
widely in respect of their dwelling places. Some construct no nest
at all or only an irregular web, and live under stones; others,
like _Theraphosa Blondii_, make a simple cylindrical tunnel, or,
like those just described, a tube having a prolonged, uncovered,
funnel-shaped mouth: others again, belonging to the genus _Atypus_,
form the curious and as yet imperfectly-understood nests with a
silken tubular lining, part of which hangs down outside; while on the
highest rung of the architectural ladder, stand the builders of the
veritable trap-door nests.
It seems quite possible that, when we know more of the structures
made by _Territelariæ_ generally in various parts of the world, we
shall find that nests of various degrees of complexity and perfection
of structure exist, bridging over the gulf between the barbarous
dwellers under stones and the highly civilized inhabitants of the
branched wafer and cork nests.
Indeed, thanks to recent discoveries, I am already able to do
something of this kind for one small group of spiders, namely, for
that of the European _Nemesias_ having nests with wafer doors.
[Illustration: _Plate XIV._]
I hope to make this plain by reference to the diagrams on Plate XIV.,
where the figures C, D, E, F, and G represent on a reduced scale five
types of wafer nest constructed by as many distinct spiders, and
where a gradation may readily be traced between the simplest type at
C and the most complicated at G; but we shall speak more fully of
this matter by-and-by.
In these diagrams I have placed that representing the nest of
_Atypus_ on the extreme left (A);[130] next to this stands that
of a nest of the cork type (B), a type which must be carefully
distinguished from all the rest. It must not be supposed that the
solid cork door (so called from its resemblance to a short cork
closing the neck of a bottle), is nothing more than a thicker edition
of the wafer door; it is not so, but, on the contrary, possesses a
very characteristic structure of its own, being composed of many
layers of silk, each furnished with a sloping rim of earth, while the
wafer door consists of but a single layer of silk.
[Footnote 130: These types may be briefly enumerated as follows:
A, nest of _Atypus_.
B, cork nest, and B, 1, layers of silk and earth forming the door of the
cork nest.
C, single-door, unbranched wafer nest.
D, single door, branched wafer nest.
E, double-door, unbranched wafer nest, and E, 1, lower door of the same.
F, the Hyères double-door branched wafer nest, and F, 1, lower door of
the same.
G, double-door branched cavity wafer nest, as seen in the oldest and
largest specimens, and G, 1, the same in the younger specimens.
G, 2, the lower door of this nest, being of the same form in young
and old nests.
]
I have represented at B 1 the 14 layers of silk and earth which went
to make a single cork door examined by me. It will be seen that the
outermost of these layers is the largest, and the innermost the
smallest, and I have already (_Ants and Spiders_, p. 150) shown
reason for believing that the latter constituted the first door the
spider ever made, and that the consecutive layers mark successive
stages in the enlargement of the nest.
There is therefore a broad distinction as to construction between
cork nests and wafer nests; moreover, while the former are, as far
as we know at present, all of one type, and only differ in size or
proportion, the latter appear under five distinct types.
Thus, every known cork nest, whether found in Europe, America, or
the Antipodes, has the same solid door and simple tube; while of the
wafer nests, some have branched and others simple tubes, and some
again possess a lower door in addition to the upper or surface door.