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RATIONING ACCORDING TO SEX




Considered in respect of quality, the food has just disclosed our profound
ignorance of the origins of instinct. Success falls to the blusterers, to
the imperturbable dogmatists, from whom anything is accepted if only they
make a little noise. Let us discard this bad habit and admit that really,
if we go to the bottom of things, we know nothing about anything.
Scientifically speaking, nature is a riddle to which human curiosity finds
no definite solution. Hypothesis follows hypothesis; the theoretical
rubbish-heap grows bigger and bigger; and still truth escapes us. To know
how to know nothing might well be the last word of wisdom.

Considered in respect of quantity, the food sets us other problems, no less
obscure. Those of us who devote ourselves assiduously to studying the
customs of the game-hunting Wasps soon find our attention arrested by a
very remarkable fact, at the time when our mind, refusing to be satisfied
with sweeping generalities, which our indolence too readily makes shift
with, seeks to enter as far as possible into the secret of the details, so
curious and sometimes so important, as and when they become better-known to
us. This fact, which has preoccupied me for many a long year, is the
variable quantity of the provisions packed into the burrow as food for the
larva.

Each species is scrupulously faithful to the diet of its ancestors. For
more than a quarter of a century I have been exploring my district; and I
have never known the diet to vary. To-day, as thirty years ago, each
huntress must have the game which I first saw her pursuing. But, though the
nature of the victuals is constant, the quantity is not so. In this respect
the difference is so great that he would need to be a very superficial
observer who should fail to perceive it on his first examination of the
burrows. In the beginning, this difference, involving two, three, four
times the quantity and more, perplexed me extremely and led me to the
conclusions which I reject to-day.

Here, among the instances most familiar to me, are some examples of these
variations in the number of victims provided for the larva, victims, of
course, very nearly identical in size. In the larder of the Yellow-winged
Sphex, after the victualling is completed and the house shut up, two or
three Crickets are sometimes found and sometimes four. Stizus ruficornis
(Cf. "The Hunting Wasps": chapter 20; also "Bramble-bees and Others":
chapter 9.--Translator's Note.), established in some vein of soft
sandstone, places three Praying Mantes in one cell and five in another. Of
the caskets fashioned by Amedeus' Eumenes (Cf." The Mason-wasps": chapter
1.--Translator's Note.) out of clay and bits of stone, the more richly
endowed contain ten small caterpillars, the more poorly furnished five. The
Sand Cerceris (Cf. "The Hunting Wasps": chapter 2.--Translator's Note.)
will sometimes provide a ration of eight Weevils and sometimes one of
twelve or even more. My notes abound in abstracts of this kind. It is
unnecessary for the purpose in hand to quote them all. It will serve our
object better if I give the detailed inventory of the Bee-eating Philanthus
and of the Mantis-hunting Tachytes, considered especially with regard to
the quantity of the victuals.

The slayer of Hive-bees is frequently in my neighbourhood; and I can obtain
from her with the least trouble the greatest number of data. In September I
see the bold filibuster flying from clump to clump of the pink heather
pillaged by the Bee. The bandit suddenly arrives, hovers, makes her choice
and swoops down. The trick is done: the poor worker, with her tongue
lolling from her mouth in the death-struggle, is carried through the air to
the underground den, which is often a very long way from the spot of the
capture. The trickling of earthy refuse, on the bare banks, or on the
slopes of footpaths, instantly reveals the dwellings of the ravisher; and,
as the Philanthus always works in fairly populous colonies, I am able, by
noting the position of the communities, to make sure of fruitful
excavations during the forced inactivity of winter.

The sapping is a laborious task, for the galleries run to a great depth.
Favier wields the pick and spade; I break the clods which he brings down
and open the cells, whose contents--cocoons and remnants of provisions--I
at once pour into a little screw of paper. Sometimes, when the larva is not
developed, the stack of Bees is intact; more often the victuals have been
consumed; but it is always possible to tell the number of items provided.
The heads, abdomens and thoraxes, emptied of their fleshy substance and
reduced to the tough outer skin, are easily counted. If the larva has
chewed these overmuch, the wings at least are left; these are sapless
organs which the Philanthus absolutely scorns. They are likewise spared by
moisture, putrefaction and time, so much so that it is no more difficult to
take an inventory of a cell several years old than one of a recent cell.
The essential thing is not to overlook any of these tiny relics while
placing them in the paper bag, amid the thousand incidents of the
excavation. The rest of the work will be done in the study, with the aid of
the lens, taking the remains heap by heap; the wings will be separated from
the surrounding refuse and counted in sets of four. The result will give
the amount of the provisions. I do not recommend this task to any one who
is not endowed with a good stock of patience, nor above all to any one who
does not start with the conviction that results of great interest are
compatible with very modest means.

My inspection covers a total of one hundred and thirty-six cells, which are
divided as in the table below:

2 cells each containing 1 Bee
52 cells each containing 2 Bees
36 cells each containing 3 Bees
36 cells each containing 4 Bees
9 cells each containing 5 Bees
1 cell containing 6 Bees
---
136

The Mantis-hunting Tachytes consumes its heap of Mantes, the horny envelope
included, without leaving any remains but scanty crumbs, quite insufficient
to establish the number of items provided. After the meal is completed, any
inventory of the rations becomes impossible. I therefore have recourse to
the cells which still contain the egg or the very young larva and, above
all, to those whose provisions have been invaded by a tiny parasitic Gnat,
a Tachina (Cf. "The Hunting Wasps": chapters 4 and 16.--Translator's
Note.), which drains the game without cutting it up and leaves the whole
skin intact. Twenty-five larders, put to the count, give me the following
result:

8 cells each containing 3 items
5 cells each containing 4 items
4 cells each containing 6 items
3 cells each containing 7 items
2 cells each containing 8 items
1 cell containing 9 items
1 cell containing 12 items
1 cell containing 16 items
---
25

The predominant game is the Praying Mantis, green; next comes the Grey
Mantis, ash-coloured. A few Empusae make up the total. The specimens vary
in dimensions within fairly elastic limits: I measure some which are a
third to a half inch long, averaging two-thirds to one inch long, and some
which are two-fifths, averaging three quarters. I see pretty plainly that
their number increases in proportion as their size diminishes, as though
the Tachytes were seeking to make up for the smallness of the game by
increasing the amount; none the less I find it quite impossible to detect
the least equivalence by combining the two factors of number and size. If
the huntress really estimates the provisions, she does so very roughly; her
household accounts are not at all well kept; each head of game, large or
small, must always count as one in her eyes.

Put on my guard, I look to see whether the honey-gathering Bees have a
double service, like the game-hunting Wasps'. I estimate the amount of
honeyed paste; I gauge the cups intended to contain it. In many cases the
result resembles the first obtained: the abundance of provisions varies
from one cell to another. Certain Osmiae (O. cornuta and O. tricornis (Cf.
"Bramble-bees and Others": passim; and, in particular, chapters 3 to 5.--
Translator's Note.)) feed their larvae on a heap of pollen-dust moistened
in the middle with a very little disgorged honey. One of these heaps may be
three or four times the size of some other in the same group of cells. If I
detach from its pebble the nest of the Mason-bee, the Chalicodoma of the
Walls, I see cells of large capacity, sumptuously provisioned; close beside
these I see others, of less capacity, with victuals parsimoniously
allotted. The fact is general; and it is right that we should ask ourselves
the reason for these marked differences in the relative quantity of
foodstuffs and for these unequal rations.

I at last began to suspect that this is first and foremost a question of
sex. In many Bees and Wasps, indeed, the male and the female differ not
only in certain details of internal or external structure--a point of view
which does not affect the present problem--but also in length and bulk,
which depend in a high degree on the quantity of food.

Let us consider in particular the Bee-eating Philanthus. Compared with the
female, the male is a mere abortion. I find that he is only a third to half
the size of the other sex, as far as I can judge by sight alone. To obtain
exactly the respective quantities of substance, I should need delicate
balances, capable of weighing down to a milligramme. My clumsy villager's
scales, on which potatoes may be weighed to within a kilogramme or so, do
not permit of this precision. I must therefore rely on the evidence of my
sight alone, evidence, for that matter, which is amply sufficient in the
present instance. Compared with his mate, the Mantis-hunting Tachytes is
likewise a pigmy. We are quite astonished to see him pestering his giantess
on the threshold of the burrows.

We observe differences no less pronounced of size--and consequently of
volume, mass and weight--in the two sexes of many Osmiae. The differences
are less emphatic, but are still on the same side, in the Cerceres, the
Stizi, the Spheges, the Chalicodomae and many more. It is therefore the
rule that the male is smaller than the female. There are of course some
exceptions, though not many; and I am far from denying them. I will mention
certain Anthidia where the male is the larger of the two. Nevertheless, in
the great majority of cases the female has the advantage.

And this is as it should be. It is the mother, the mother alone, who
laboriously digs underground galleries and chambers, kneads the plaster for
coating the cells, builds the dwelling-house of cement and bits of grit,
bores the wood and divides the burrow into storeys, cuts the disks of leaf
which will be joined together to form honey-pots, works up the resin
gathered in drops from the wounds in the pine-trees to build ceilings in
the empty spiral of a Snail-shell, hunts the prey, paralyses it and drags
it indoors, gathers the pollen-dust, prepares the honey in her crop, stores
and mixes the paste. This severe labour, so imperious and so active, in
which the insect's whole life is spent, manifestly demands a bodily
strength which would be quite useless to the male, the amorous trifler.
Thus, as a general rule, in the insects which carry on an industry the
female is the stronger sex.

Does this pre-eminence imply more abundant provisions during the larval
stage, when the insect is acquiring the physical growth which it will not
exceed in its future development? Simple reflection supplies the answer:
yes, the aggregate growth has its equivalent in the aggregate provisions.
Though so slight a creature as the male Philanthus finds a ration of two
Bees sufficient for his needs, the female, twice or thrice as bulky, will
consume three to six at least. If the male Tachytes requires three Mantes,
his consort's meal will demand a batch of something like ten. With her
comparative corpulence, the female Osmia will need a heap of paste twice or
thrice as great as that of her brother, the male. All this is obvious; the
animal cannot make much out of little.

Despite this evidence, I was anxious to enquire whether the reality
corresponded with the previsions of the most elementary logic. Instances
are not unknown in which the most sagacious deductions have been found to
disagree with the facts. During the last few years, therefore, I have
profited by my winter leisure to collect, from spots noted as favourable
during the working-season, a few handfuls of cocoons of various Digger-
wasps, notably of the Bee-eating Philanthus, who has just furnished us with
an inventory of provisions. Surrounding these cocoons and thrust against
the wall of the cell were the remnants of the victuals--wings, corselets,
heads, wing-cases--a count of which enabled me to determine how many head
of game had been provided for the larva, now enclosed in its silken abode.
I thus obtained the correct list of provisions for each of the huntress'
cocoons. On the other hand, I estimated the quantities of honey, or rather
I gauged the receptacles, the cells, whose capacity is proportionate to the
mass of the provisions stored. After making these preparations, registering
the cells, cocoons and rations and putting all my figures in order, I had
only to wait for the hatching-season to determine the sex.

Well, I found that logic and experiment were in perfect agreement. The
Philanthus-cocoons with two Bees gave me males, always males; those with a
larger ration gave me females. From the Tachytes-cocoons with double or
treble that ration I obtained females. When fed upon four or five Nut-
weevils, the Sand Cerceris was a male; when fed upon eight or ten, a
female. In short, abundant provisions and spacious cells yield females;
scanty provisions and narrow cells yield males. This is a law upon which I
may henceforth rely.

At the stage which we have now reached a question arises, a question of
major importance, touching the most nebulous aspect of embryogeny. How is
it that the larva of the Philanthus, to take a particular case, receives
three to five Bees from its mother when it is to become a female and not
more than two when it is to become a male? Here the various head of game
are identical in size, in flavour, in nutritive properties. The food-value
is precisely in proportion to the number of items supplied, a helpful
detail which eliminates the uncertainties wherein we might be left by the
provision of game of different species and varying sizes. How is it, then,
that a host of Bees and Wasps, of honey-gatherers as well as huntresses,
store a larger or smaller quantity of victuals in their cells according as
the nurselings are to become females or males?

The provisions are stored before the eggs are laid; and these provisions
are measured by the needs of the sex of an egg still inside the mother's
body. If the egg-laying were to precede the rationing, which occasionally
takes place, as with the Odyneri (Cf. "The Hunting Wasps": chapters 2 and
8.--Translator's Note.), for example, we might imagine that the gravid
mother enquires into the sex of the egg, recognizes it and stacks victuals
accordingly. But, whether destined to become a male or a female, the egg is
always the same; the differences--and I have no doubt that there are
differences--are in the domain of the infinitely subtle, the mysterious,
imperceptible even to the most practised embryogenist. What can a poor
insect see--in the absolute darkness of its burrow, moreover--where science
armed with optical instruments has not yet succeeded in seeing anything?
And besides, even were it more discerning than we are in these genetic
obscurities, its visual discernment would have nothing whereupon to
practice. As I have said, the egg is laid only when the corresponding
provisions are stored. The meal is prepared before the larva which is to
eat it has come into the world. The supply is generously calculated by the
needs of the coming creature; the dining-room is built large or small to
contain a giant or a dwarf still germinating in the ovarian ducts. The
mother, therefore, knows the sex of her egg beforehand.

A strange conclusion, which plays havoc with our current notions! The logic
of the facts leads us to it directly. And yet it seems so absurd that,
before accepting it, we seek to escape the predicament by another
absurdity. We wonder whether the quantity of food may not decide the fate
of the egg, originally sexless. Given more food and more room, the egg
would become a female; given less food and less room, it would become a
male. The mother, obeying her instincts, would store more food in this case
and less in that; she would build now a large and now a small cell; and the
future of the egg would be determined by the conditions of food and
shelter.

Let us make every test, every experiment, down to the absurd: the crude
absurdity of the moment has sometimes proved to be the truth of the morrow.
Besides, the well-known story of the Hive-bee should make us wary of
rejecting paradoxical suppositions. Is it not by increasing the size of the
cell, by modifying the quality and quantity of the food, that the
population of a hive transforms a worker larva into a female or royal
larva? It is true that the sex remains the same, since the workers are only
incompletely developed females. The change is none the less miraculous, so
much so that it is almost lawful to enquire whether the transformation may
not go further, turning a male, that poor abortion, into a sturdy female by
means of a plentiful diet. Let us therefore resort to experiment.

I have at hand some long bits of reed in the hollow of which an Osmia, the
Three-horned Osmia, has stacked her cells, bounded by earthen partitions. I
have related elsewhere (Cf. "Bramble-bees and Others": chapters 2 to 5.--
Translator's Note.) how I obtain as many of these nests as I could wish
for. When the reed is split lengthwise, the cells come into view, together
with their provisions, the egg lying on the paste, or even the budding
larva. Observations multiplied ad nauseam have taught me where to find the
males and where the females in this apiary. The males occupy the fore-part
of the reed, the end next to the opening; the females are at the bottom,
next to the knot which serves as a natural stopper to the channel. For the
rest, the quantity of the provisions in itself points to the sex: for the
females it is twice or thrice as great as for the males.

In the scantily-provided cells, I double or treble the ration with food
taken from other cells; in the cells which are plentifully supplied, I
reduce the portion to a half or a third. Controls are left: that is to say,
some cells remain untouched, with their provisions as I found them, both in
the part which is abundantly provided and in that which is more meagrely
rationed. The two halves of the reed are then restored to their original
position and firmly bound with a few turns of wire. We shall see, when the
time comes, whether these changes increasing or decreasing the victuals
have determined the sex.

Here is the result: the cells which at first were sparingly provided, but
whose supplies were doubled or trebled by my artifice, contain males, as
foretold by the original amount of victuals. The surplus which I added has
not completely disappeared, far from it: the larva has had more than it
needed for its evolution as a male; and, being unable to consume the whole
of its copious provisions, it has spun its cocoon in the midst of the
remaining pollen-dust. These males, so richly supplied, are of handsome but
not exaggerated proportions; you can see that the additional food has
profited them to some small extent.

The cells with abundant provisions, reduced to a half or a third by my
intervention, contain cocoons as small as the male cocoons, pale,
translucent and limp, whereas the normal cocoons are dark-brown, opaque and
firm to the touch. These, we perceive at once, are the work of starved,
anaemic weavers, who, failing to satisfy their appetite and having eaten
the last grain of pollen, have, before dying, done their best with their
poor little drop of silk. Those cocoons which correspond with the smallest
allowance of food contain only a dead and shrivelled larva; others, in
whose case the provisions were less markedly decreased, contain females in
the adult form, but of very diminutive size, comparable with that of the
males, or even smaller. As for the controls which I was careful to leave,
they confirm the fact that I had males in the part near the orifice of the
reed and females in the part near the knot closing the channel.

Is this enough to dispose of the very improbable supposition that the
determination of the sex depends on the quantity of food? Strictly
speaking, there is still one door open to doubt. It may be said that
experiment, with its artifices, does not succeed in realizing the delicate
natural conditions. To make short work of all objections, I cannot do
better than have recourse to facts in which the experimenter's hand has not
intervened. The parasites will supply us with these facts; they will show
us how alien the quantity and even the quality of the food are from either
specific or sexual characters. The subject of enquiry thus becomes double,
instead of single as it was when I plundered one cell in my split reeds to
enrich another. Let us follow this double current for a little while.

An Ammophila, the Silky Ammophila (Cf. "The Hunting Wasps": chapter 13.--
Translator's Note.), which feeds on Looper caterpillars (Known also as
Measuring-worms, Inchworms, Spanworms and Surveyors: the caterpillars of
the Geometrid Moths.--Translator's Note.), has just been reared in my
refectory on Spiders. Replete to the regulation point, it spins its cocoon.
What will emerge from this? If the reader expects to see any modifications,
caused by a diet which the species, left to itself, had never effected, let
him be undeceived and that quickly. The Ammophila fed on Spiders is
precisely the same as the Ammophila fed on caterpillars, just as man fed on
rice is the same as man fed on wheat. In vain I pass my lens over the
product of my art: I cannot distinguish it from the natural product; and I
defy the most meticulous entomologist to perceive any difference between
the two. It is the same with my other boarders who have had their diet
altered.

I see the objection coming. The differences may be inappreciable, for my
experiments touch only a first rung of the ladder. What would happen if the
ladder were prolonged, if the offspring of the Ammophila fed on Spiders
were given the same food generation after generation? These differences, at
first imperceptible, might become accentuated until they grew into distinct
specific characters; the habits and instincts might also change; and in the
end the caterpillar-huntress might become a Spider-huntress, with a shape
of her own. A species would be created, for, among the factors at work in
the transformation of animals, the most important of all is incontestably
the type of food, the nature of the thing wherewith the animal builds
itself. All this is much more important than the trivialities which Darwin
relies upon.

To create a species is magnificent in theory, so that we find ourselves
regretting that the experimenter is not able to continue the attempt. But,
once the Ammophila has flown out of the laboratory to slake her thirst at
the flowers in the neighbourhood, just to try to find her again and induce
her to entrust you with her eggs, which you would rear in the refectory, to
increase the taste for Spiders from generation to generation! Merely to
dream of it were madness. Shall we, in our helplessness, admit ourselves
beaten by the evolutionary effects of diet? Not a bit of it! One
experiment--and you could not wish for a more decisive--is continually in
progress, apart from all artifices, on an enormous scale. It is brought to
our notice by the parasites.

They must, we are told, have acquired the habit of living on others in
order to save themselves work and to lead an easier life. The poor wretches
have made a sorry blunder. Their life is of the hardest. If a few establish
themselves comfortably, dearth and dire famine await most of the rest.
There are some--look at certain of the Oil-beetles--exposed to so many
chances of destruction that, to save one, they are obliged to procreate a
thousand. They seldom enjoy a free meal. Some stray into the houses of
hosts whose victuals do not suit them; others find only a ration quite
insufficient for their needs; others--and these are very numerous--find
nothing at all. What misadventures, what disappointments do these needy
creatures suffer, unaccustomed as they are to work! Let me relate some of
their misfortunes, gleaned at random.

The Girdled Dioxys (D. cincta) loves the ample honey-stores of the
Chalicodoma of the Pebbles. There she finds abundant food, so abundant that
she cannot eat it all. I have already passed censure on this waste. (Cf.
"The Mason-bees": chapter 10.--Translator's Note.) Now a little Osmia (O.
cyanoxantha, Perez) makes her nest in the Mason's deserted cells; and this
Bee, a victim of her ill-omened dwelling, also harbours the Dioxys. This is
a manifest error on the parasite's part. The nest of the Chalicodoma, the
hemisphere of mortar on its pebble, is what she is looking for, to confide
her eggs to it. But the nest is now occupied by a stranger, by the Osmia, a
circumstance unknown to the Dioxys, who comes stealing up to lay her egg in
the mother's absence. The dome is familiar to her. She could not know it
better if she had built it herself. Here she was born; here is what her
family wants. Moreover, there is nothing to arouse her suspicions: the
outside of the home has not changed its appearance in any respect; the
stopper of gravel and green putty, which later will form a violent contrast
with its white front, is not yet constructed. She goes in and sees a heap
of honey. To her thinking this can be nothing but the Chalicodoma's
portion. We ourselves would be beguiled, in the Osmia's absence. She lays
her eggs in this deceptive cell.

Her mistake, which is easy to understand, does not in any way detract from
her great talents as a parasite, but it is a serious matter for the future
larva. The Osmia, in fact, in view of her small dimensions, collects but a
very scanty store of food: a little loaf of pollen and honey, hardly the
size of an average pea. Such a ration is insufficient for the Dioxys. I
have described her as a waster of food when her larva is established,
according to custom, in the cell of the Mason-bee. This description no
longer applies; not in the very least. Inadvertently straying to the
Osmia's table, the larva has no excuse for turning up its nose; it does not
leave part of the food to go bad; it eats up the lot without having had
enough.

This famine-stricken refectory can give us nothing but an abortion. As a
matter of fact, the Dioxys subjected to this niggardly test does not die,
for the parasite must have a tough constitution to enable it to face the
disastrous hazards which lie in wait for it; but it attains barely half its
ordinary dimensions, which means one-eighth of its normal bulk. To see it
thus diminished, we are surprised at its tenacious vitality, which enables
it to reach the adult form in spite of the extreme deficiency of food.
Meanwhile, this adult is still the Dioxys; there is no change of any kind
in her shape or colouring. Moreover, the two sexes are represented; this
family of pigmies has its males and females. Dearth and the farinaceous
mess in the Osmia's cell has had no more influence over species or sex than
abundance and flowing honey in the Chalicodoma's home.

The same may be said of the Spotted Sapyga (S. punctata (A parasitic Wasp.
Cf. "The Mason-bees": chapters 9 and 10.--Translator's Note.)), which, a
parasite of the Three-pronged Osmia, a denizen of the bramble, and of the
Golden Osmia, an occupant of empty Snail-shells, strays into the house of
the Tiny Osmia (O. parvula (This bee makes her home in the brambles. Cf.
"Bramble-dwellers and Others": chapters 2 and 3.--Translator's Note.)),
where, for lack of sufficient food, it does not attain half its normal
size.

A Leucopsis (Cf. "The Mason-bees": chapter 11.--Translator's Note.) inserts
her eggs through the cement wall of our three Chalicodomae. I know her
under two names. When she comes from the Chalicodoma of the Pebbles or
Walls, whose opulent larva saturates her with food, she deserves by her
large size the name of Leucopsis gigas, which Fabricius bestows upon her;
when she comes from the Chalicodoma of the Sheds, she deserves no more than
the name of L. grandis, which is all that Klug grants her. With a smaller
ration "the giant" is to some degree diminished and becomes no more than
"the large." When she comes from the Chalicodoma of the Shrubs, she is
smaller still; and, if some nomenclator were to seek to describe her, she
would no longer deserve to be called more than middling. From dimension 2
she has descended to dimension 1 without ceasing to be the same insect,
despite the change of diet; and at the same time both sexes are present in
the three nurselings, despite the variation in the quantity of victuals.

I obtain Anthrax sinuata ("The Mason-bees": chapters 8, 10 and 11.--
Translator's Note.) from various bees' nests. When she issues from the
cocoons of the Three-horned Osmia, especially the female cocoons, she
attains the greatest development that I know of. When she issues from the
cocoons of the Blue Osmia (O. cyanea, KIRB.), she is sometimes hardly one-
third the length which the other Osmia gives her. And we still have the two
sexes--that goes without saying--and still identically the same species.

Two Anthidia, working in resin, A. septemdentatum, LATR., and A.
bellicosum, LEP. (For these Resin-bees, cf. "Bramble-bees and Others":
chapter 10.--Translator's Note.), establish their domicile in old Snail-
shells. The second harbours the Burnt Zonitis (Z. proeusta (Cf. "The Glow-
worm and Other Beetles": chapter 6.--Translator's Note.)). Amply nourished
this Meloe then acquires her normal size, the size in which she usually
figures in the collections. A like prosperity awaits her when she usurps
the provisions of Megachile sericans. (For this Bee, the Silky Leaf-cutter,
cf. "Bramble-bees and Others": chapter 8.--Translator's Note.) But the
imprudent creature sometimes allows itself to be carried away to the meagre
table of the smallest of our Anthidia (A. scapulare, LATR. (A Cotton-bee,
cf. idem: chapter 9.--Translator's Note.)), who makes her nests in dry
bramble-stems. The scanty fare makes a wretched dwarf of the offspring
belonging to either sex, without depriving them of any of their racial
features. We still see the Burnt Zonitis, with the distinctive sign of the
species: the singed patch at the tip of the wing-cases.

And the other Meloidae--Cantharides, Cerocomae, Mylabres (For these
Blister-beetles or Oil-beetles, cf. "The Glow-worm and Other Beetles":
chapter 6.--Translator's Note.)--to what inequalities of size are they not
subject, irrespective of sex! There are some--and they are numerous--whose
dimensions fall to a half, a third, a quarter of the regular dimensions.
Among these dwarfs, these misbegotten ones, these victims of atrophy, there
are females as well as males; and their smallness by no means cools their
amorous ardour. These needy creatures, I repeat, have a hard life of it.
Whence do they come, these diminutive Beetles, if not from dining-rooms
insufficiently supplied for their needs? Their parasitical habits expose
them to harsh vicissitudes. No matter: in dearth as well as in abundance
the two sexes appear and the specific features remain unchanged.

It is unnecessary to linger longer over this subject. The demonstration is
completed. The parasites tell us that changes in the quantity and quality
of food do not lead to any transformation of species. Fed upon the larva of
the Three-horned Osmia or of the Blue Osmia, Anthrax sinuata, whether of
handsome proportions or a dwarf, is still Anthrax sinuata; fed upon the
allowance of the Anthidium of the empty Snail-shells, the Anthidium of the
brambles, the Megachile or doubtless many others, the Burnt Zonitis is
still the Burnt Zonitis. Yet variation of diet ought to be a very potential
factor in the problem of progress towards another form. Is not the world of
living creatures ruled by the stomach? And the value of this factor is
unity, changing nothing in the product.

The same parasites tell us--and this is the chief object of my digression--
that excess or deficiency of nutriment does not determine the sex. So we
are once more confronted with the strange proposition, which is now more
positive than ever, that the insect which amasses provisions in proportion
to the needs of the egg about to be laid knows beforehand what the sex of
this egg will be. Perhaps the reality is even more paradoxical still. I
shall return to the subject after discussing the Osmiae, who are very
weighty witnesses in this grave affair. (Cf. "Bramble-bees and Others":
chapters 3 to 5. The student is recommended to read these three chapters in
conjunction with the present chapter, to which they form a sequel, with
that on the Osmiae (chapter 2 of the above volume) intervening.--
Translator's Note.)





Next: THE BEE-EATING PHILANTHUS

Previous: A DIG AT THE EVOLUTIONISTS



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