CONCLUSION
From the facts recorded in the preceding chapters it is clear that there
are difficulties in the way of accepting the mimicry theory as an
explanation of the remarkable resemblances which are often found between
butterflies belonging to distinct groups. Of these difficulties two stand
out beyond the rest, viz., the difficulty of finding the agent that shall
exercise the appropriate powers of discrimination, and the difficulty of
fitting in the theoretical process involving the incessant accumulation of
minute variations with what is at present known of the facts of heredity.
With regard to the former of these two difficulties we have seen that the
supporters of the theory regard birds as the main selective agent. At the
outset we are met with the fact that relatively few birds have been
observed to prey habitually on butterflies, while some at any rate of those
that do so shew no discrimination between what should be theoretically
pleasant to eat and what should not be pleasant. Even if birds are the
postulated enemies it must be further shewn that they exercise the
postulated discrimination. It is required of them that they should do two
things. {140} In the first place they must confuse an incipient or "rough"
mimic with a model sufficiently often to give it an advantage over those
which have not varied in the direction of the model. In other words, they
must be easily taken in. Secondly, they are expected to bring about those
marvellously close resemblances that sometimes occur by confusing the exact
mimicking pattern with the model, while at the same time eliminating those
which vary ever so little from it. In other words, they must be endowed
with most remarkably acute powers of discrimination. Clearly one cannot ask
the same enemy to play both parts. If, therefore, birds help to bring about
the resemblance we must suppose that it is done by different species--that
there are some which do the rough work, others which do the smoothing, and
others again which put on the final polish and keep it up to the mark. This
is, of course, a possibility, but before it can be accepted as a
probability some evidence must be forthcoming in its favour.
But even if the difficulty of the appropriate enemy be passed over, and it
be granted that a mimetic resemblance can be built up through a number of
small separate steps, which have become separately established through the
agency of separate species of birds with various but distinct
discriminating powers, we are left face to face with an even more serious
physiological difficulty. For why is it that when the end form which is
supposed to have resulted from this process is crossed back with the
original form all {141} the intermediate steps do not reappear? Why is it
that when the altered germplasm is mingled with the original germplasm the
various postulated stages between them are not reformed? For in various
cases where we know the course of evolution this does occur. The pale pink
sweet-pea has come from the wild purple by a series of definite steps, and
when it is crossed back with the wild form the resulting plants give the
series of stages that have occurred in the evolution of the pink. So also
when the orange rabbit is crossed with the wild grey form and the offspring
are inbred there are reproduced the black, the tortoiseshell, and the
chocolate, forms which are stages in the evolution of the orange from the
wild grey. If then, to take an example, the "aristolochiae" form of
_Papilio polytes_ has been derived from the male-like form by a series of
steps, why do we not get these steps reproduced after the germplasms of the
two forms have been mingled? From the standpoint of modern genetic work the
inference is that these postulated intermediate steps have never
existed--that the one form of _polytes_ female came directly from the
other, and was not built up gradually through a series of stages by the
selective agency of birds or any other discriminating enemy.
These two objections, viz. the difficulty of finding the appropriate enemy,
and the non-appearance of intermediates when the extreme forms are crossed,
may, perhaps, be said to constitute the main objections to the current
theory of mimicry. Others such as {142} the relative scarcity of mimicry in
the male sex and the existence of cases of polymorphism among females of a
species which cannot possibly be explained on mimetic lines have already
been mentioned. But while the main objections remain it is hardly necessary
to insist upon these others. Looked at critically in the light of what we
now know about heredity and variation the mimicry hypothesis is an
unsatisfactory explanation of the way in which these remarkable
resemblances between different species of butterflies have been brought
about. Sometimes this is admitted by those who nevertheless embrace the
theory with a mild aloofness. For they argue that even though it does not
explain all the facts no other theory explains so many. Others have sought
an explanation in what has sometimes been termed the hypothesis of external
causes, regarding these resemblances as brought about by similar conditions
of soil and climate, and so forth. It is not inconceivable that certain
types of colour and pattern may be the expression of deep-seated
physiological differences, which place their possessors at an advantage as
compared with the rest of the species. Were this so it is but reasonable to
suppose that they would become established through the agency of natural
selection. But it is difficult, if not impossible, to regard this as a
satisfactory solution, if for no other reason than that it offers no
explanation of polymorphism. For example, each of the three forms of
_polytes_ female holds its own and all must, therefore, be regarded as
equally well adapted to the circumstances under which {143} they live. They
are so distinct in colour that it is difficult on this hypothesis to
suppose that they are all on the same footing in respect to their
environment. Yet if one is better off than the others, how is it that these
still exist?
Those who have examined long series of these cases of resemblance among
butterflies find it hard to believe that there is not some connection
between them apart from climatic influence. One feels that they are too
numerous and too striking to be all explained away as mere coincidences
engendered by like conditions. Nor is it improbable that natural selection
in the form of the discriminating enemy may have played a part in
connection with them, though a different one from that advocated on the
current theory of mimicry. If we assume that sudden and readily appreciable
variations of the nature of "sports" turn up from time to time, and if
these variations happen to resemble a form protected by distastefulness so
closely that the two can be confused by an enemy which has learned to avoid
the latter, then there would appear to be good grounds for the mimicking
sport becoming established as the type form of the species. For it has
already been seen that a rare sport is not swamped by intercrossing with
the normal form, but that on the contrary if it possess even a slight
advantage, it must rapidly displace the form from which it sprang (cf.
Chap. VIII). On this view natural selection in the form of the
discriminating enemy will have played its part, but now with a difference.
Instead of building up a {144} mimetic likeness bit by bit it will merely
have conserved and rendered numerically preponderant a likeness which had
turned up quite independently. The function of natural selection in respect
of a mimetic likeness lies not in its formation but in its conservation. It
does not bring about the likeness, neither does it accentuate it: it brings
about the survival of those forms which happen to shew the likeness. Why
variations on the part of one species should bear a strong resemblance to
other, and often distantly related, species is another question altogether.
Even a superficial survey of the facts makes it evident that cases of
mimicry tend to run in series--that a closely related series of mimics,
though often of very different pattern and colour, tends to resemble a
closely related series of models. In Asia we have the Cosmodesmus Papilios
mimicking a series of Danaines, while the true Papilios (cf. Appendix II)
tend to resemble a series of the less conspicuous members of the
Pharmacophagus group. In the same region the various species of _Elymnias_
form a series resembling a series of Danaines. In Africa there stands out
the Cosmodesmus group again mimicking a Danaine series, and in part also an
Acraeine series. Overlapping the Acraeines again are various forms of the
Nymphaline genus _Pseudacraea_. It is also of interest that in _Danais
chrysippus_ and _Acraea encedon_ the Danaine and Acraeine series overlap
(cf. Pl. IX). Similar phenomena occur also in South America, where closely
parallel series of colour patterns are exhibited by several {145}
Ithomiines, by _Heliconius_, _Lycorea_, _Dismorphia_, and other genera (cf.
p. 39). On the other hand such mimetic resemblances as are shewn by the
South American Swallow-tails of the Papilio and Cosmodesmus groups are
almost all with the Pharmacophagus group, and almost all of the red-black
kind (cf. p. 43).
On the whole it may be stated that the majority of cases of mimicry fall
into one or other of such series as the above. If we select a case of
mimicry at random we shall generally find that there are at least several
close allies of the mimic resembling several close allies of the model.
Isolated cases such as the resemblance between _Pareronia_ and _Danais_ (p.
23), between _Archonias_ and a Pharmacophagus Papilio (p. 43), or the
extraordinary instance of _Papilio laglaizei_ and _Alcidis agathyrsus_,
must be regarded as exceptional.
We have before us then a number of groups of butterflies each with a series
of different colour patterns. In each group a portion of the series
overlaps a portion of the series belonging to another more or less
distantly related group. In the light of recent discoveries connected with
heredity and variation the natural interpretation to such a set of
phenomena would be somewhat as follows: Each group of Lepidoptera, such as
those just discussed, contains, spread out among its various members, a
number of hereditary factors for the determination of colour pattern.
Within the group differences of pattern depend upon the presence or absence
of this or that factor, the variety of pattern being the result of the many
possible permutations and {146} combinations of these colour factors.
Within the limits of each group is found a definite number of these
factors--more in one group, less in another. But some factors may be common
to two or more groups, in which case some of the permutations of the
factors would be similar in the groups and would result in identical or
nearly identical pattern. To take a simple example in illustration, let us
suppose that a given group, ([alpha]), contains the eight factors A-H.
Since any species in the group may exhibit any combination of one or more
of these factors it follows that a considerable number of different forms
are possible. Now suppose that another group, ([beta]), distinguished from
([alpha]) by definite structural features, also contains eight factors
within the group, and that these factors are F-M, F, G, and H being common
to both ([alpha]) and ([beta]). Any combination therefore in ([alpha])
lacking the factors A-E will be paralleled by any combination in ([beta])
lacking the factors I-M. For in both cases we should be dealing only with
the factors F, G, and H, which are common to each group. So again a third
group might have some factors in common with ([alpha]) and some with
([beta]), and so on for other groups. In this way certain of the series of
colour patterns found in ([beta]) would overlap certain of those in
([alpha]), while others of the groups ([beta]) and ([alpha]) might overlap
those found in different groups again. The striking resemblances not
infrequently found between species belonging to quite distinct groups would
on this view depend upon the hereditary factors for pattern and colour
being limited {147} in number, so that the same assortment might not
infrequently be brought together even though the group whose members
exhibited the resemblance might, owing to structural differences, be placed
in different families.
We know from recent experimental work that something of the sort is to be
found in the coat colours of different rodents. Agouti, black, chocolate,
blue-agouti, blue, and fawn form a series of colours common to the rabbit,
the mouse, and the guinea-pig. These colours are related to each other in
the same way in these different beasts. In the rat, on the other hand,
there occur of this range of colours only the agouti and the black. Each of
these species again has certain colour patterns which are peculiar to
itself, such as the "English" type in the rabbit, the tricolor pattern in
the guinea-pig, or the "hooded" variety in the rat. The total range of
colour and pattern is somewhat different for each species, but a few are
common to them all. Moreover, there are others which are common to the
mouse and the rabbit but are not found in the guinea-pig, and others again
which may occur in the rabbit and the guinea-pig but have not been met with
in the other two. In certain features the rabbit might be said to "mimic"
the mouse, and in other features the guinea-pig. It is not, of course,
suggested that the case of the butterflies is so simple as that of the
rodents, but so far as we can see at present there would seem to be no
reason why the explanation should not be sought along the same lines. {148}
On this view the various colour patterns found among butterflies depend
primarily upon definite hereditary factors of which the number is by no
means enormous. Many of these factors are common to several or many
different groups, and a similar aggregate of colour factors, whether in an
Ithomiine, a Pierid, or a Papilio, results in a similar colour scheme. The
likeness may be close without being exact because the total effect is
dependent in some degree on the size and relative frequency of the scales
and other structural features. In so far as pattern goes _Hypolimnas
dubius_ and _Amauris echeria_ (Pl. VIII, figs. 7 and 8) are exceedingly
close. But inspection at once reveals a difference in the quality of the
scaling, giving to the _Hypolimnas_, where the black and yellow meet, a
softness or even raggedness of outline, which is distinct from the sharper
and more clear-cut borders of the _Amauris_. It is not unreasonable to
suppose that these species carry identical factors for colour pattern, and
that the differences by which the eye distinguishes them are dependent upon
the minuter structural differences such as occur in the scaling. So the eye
would distinguish between a pattern printed in identical colours on a piece
of cretonne and a piece of glazed calico. Though pattern and colour were
the same the difference in material would yield a somewhat different
effect.
On the view suggested the occurrence of mimetic resemblances is the
expression of the fact that colour pattern is dependent upon definite
hereditary factors of which the total number is by no means very great.
{149} As many of the factors are common to various groups of butterflies it
is to be expected that certain of the colour patterns exhibited by one
group should be paralleled by certain of those found in another group. That
cases of resemblance should tend to run in parallel series in different
groups is also to be expected, for in some groups the number of factors in
common is likely to be greater than in other groups. In consonance with
this view is the fact that where polymorphism occurs among the females of a
mimicking species the models, though often widely different in appearance,
are, as a rule, closely related. Some of the Asiatic Papilios, for
instance, resemble Danaines, while others resemble Pharmacophagus Papilios.
But although the polymorphism exhibited by the females of a given species
may be very marked, we do not find one of them resembling a Danaine and
another a Pharmacophagus Swallow-tail. The models of a polymorphic mimic
are almost always closely related species[89].
In discussing the problems of mimicry more attention is naturally paid to
groups which exhibit the phenomenon than to those which either do not do
so, or else only do so to a very limited extent. Yet the latter may be of
considerable interest. Among the Pieridae of the Old World the phenomenon
of mimicry is very rare. _Pareronia_ and _Aporia agathon_ conform {150}
closely to the common Danaid type represented by _Danais vulgaris_ and
other species, but apart from these none of the many Pierids in Asia
resemble any of the recognised models. Africa is apparently destitute of
Pierids which mimic species belonging to other groups. Yet no group of
butterflies is more persecuted by birds. Of all the instances of bird
attacks collected together by Marshall[90] more than one-third are
instances of attacks upon this group alone. If birds are the agents by
which mimetic likenesses are built up through the cumulative selection of
small variations, how can the rarity or absence of mimetic Pierids in the
Old World be accounted for? For the species of Pierids, like the species of
other families, shew considerable variation, and if this process of
selection were really at work one would expect to find many more Pierid
mimics in these regions than actually occur. It is true that the white,
yellow, and red pigments found in Pierids differ from those of other
butterflies in being composed either of uric acid or of some substance
closely allied to that body[91]. These substances are generally found
between the two layers of chitin, of which the scale is composed, whereas
the black pigment is intimately associated with the chitin of the scale
itself. What is perhaps the principal factor in the formation of a mimetic
likeness is the distribution of the black pigment with reference to the
lighter pigments; and although the latter are chemically distinct {151} in
the Pierids as compared with other butterflies, there would seem to be no
reason why the same factors governing the distribution of black should not
be common to members of different groups. A distribution of black pigment
similar to that found in a model and its mimic may occur also in a
non-mimetic ally of the mimic. _Dismorphia astynome_, for example,
resembles the Ithomiine _Mechanitis lysimnia_ (Pl. XV, fig. 8) both in the
distribution of black as well as of yellow and bright brown pigments. A
similar distribution of the black pigment is also found in _Dismorphia
avonia_, but the yellow and bright brown of the other two species is here
replaced with white. By a slight though definite alteration in chemical
composition this white pigment could be changed into bright brown and
yellow with the result that _D. avonia_ would closely resemble _D.
astynome_ in its colour scheme and would in this way also become a mimic of
_Mechanitis lysimnia_. Another good instance is that of the females of
_Perrhybris demophile_ and _P. lorena_, the former being black and white,
whereas in the latter the white is replaced by yellow and bright brown,
giving the insect a typical Ithomiine appearance[92]. Here again a definite
small change in the composition of the pigment laid down in the scales
would result in the establishing of a mimetic likeness where there would
otherwise be not even a suggestion of it. It is in accordance with what we
know to-day of variation {152} that such a change should appear suddenly,
complete from the start. And if so there is no difficulty in supposing that
it might be of some advantage to its possessor through the resemblance to
an unpalatable form. Even were the advantage but a slight one it is clear
from previous discussion (p. 96) that the new variety would more or less
rapidly replace the form from which it had sprung. With the continued
operation of natural selection the new form would entirely supplant the
original one, but it is not impossible that in some cases the selecting
agent may be removed before this result has been achieved. In this event
the proportions of the new and the old form would fall into a condition of
equilibrium as in _P. polytes_ in Ceylon, until some other selective agent
arose to disturb the balance. On this view natural selection is a real
factor in connection with mimicry, but its function is to conserve and
render preponderant an already existing likeness, not to build up that
likeness through the accumulation of small variations, as is so generally
assumed. Recent researches in heredity and variation all point to this
restriction of the scope of natural selection. Hitherto an argument in
favour of the older view has been that derived from the study of
adaptation--of an apparent purpose, which, at first sight, appears to be
behind the manner in which animals fit into their surroundings. For many
the explanation of this apparent purpose has been found in the process of
natural selection operating gradually upon small variations, accumulating
some and rejecting {153} others, working as it were upon a plastic
organism, moulding it little by little to a more and more perfect
adaptation to its surroundings. On this view adaptation is easy to
understand. The simplicity of the explanation is in itself attractive. But
when the facts come to be examined critically it is evident that there are
grave, if not insuperable, difficulties in the way of its acceptance. To
outline some of these has been the object of the present essay. Though
suggestions have been made as to the lines along which an explanation may
eventually be sought it is not pretended that the evidence is yet strong
enough to justify more than suggestions. Few cases of mimicry have as yet
been studied in any detail, and until this has been done many of the points
at issue must remain undecided. Nevertheless, the facts, so far as we at
present know them, tell definitely against the views generally held as to
the part played by natural selection in the process of evolution.
* * * * *
{154}
APPENDIX I
For the table on p. 155 I am indebted to the kindness of Mr H. T. J. Norton
of Trinity College, Cambridge. It affords an easy means of estimating the
change brought about through selection with regard to a given hereditary
factor in a population of mixed nature mating at random. It must be
supposed that the character depending upon the given factor shews complete
dominance, so that there is no visible distinction between the homozygous
and the heterozygous forms. The three sets of figures in the left-hand
column indicate different positions of equilibrium in a population
consisting of homozygous dominants, heterozygous dominants, and recessives.
The remaining columns indicate the number of generations in which a
population will pass from one position of equilibrium to another, under a
given intensity of selection. The intensity of selection is indicated by
the fractions 100/50, 100/75, etc. Thus 100/75 means that where the chances
of the favoured new variety of surviving to produce offspring are 100,
those of the older variety against which selection is operating are as 75;
there is a 25% selection rate in favour of the new form.
The working of the table may perhaps be best explained by a couple of
simple examples.
In a population in equilibrium consisting of homozygous dominants,
heterozygous dominants and recessives the last named class comprises 2.8%
of the total: assuming that a 10% selection rate now operates in its favour
as opposed to the two classes of dominants--in how many generations will
the recessive come to constitute one-quarter of the population? The answer
is to be looked for in column B (since the favoured variety is recessive)
under the fraction 100/90. The recessive passes from 2.8% to 11.1% of the
population in 36 generations, and from 11.1% to 25% in a further 16
generations--_i.e._ under a 10% selection rate in its favour the proportion
of the recessive rises from 2.8% to 25% in 52 generations.
{155}
A: Where the new variety is dominant
+-----------+-----------+----------+------------------------------------+
| | | | Number of generations taken |
|Percentage |Percentage |Percentage| to pass from one position |
|of total |of total |of total | to another as indicated |
|population |population |population| in the percentages of different |
|formed by |formed by |formed by | individuals in left-hand column. |
|old variety|the hybrids|the new +--------+--------+--------+---------+
| | |variety | 100/50 | 100/75 | 100/90 | 100/99 |
+-----------+-----------+----------+--------+--------+--------+---------+
| 99.9 | .09 | .000 | | | | |
| 98.0 | 1.96 | .008 | 4 | 10 | 28 | 300 |
| 90.7 | 9.0 | .03 | 2 | 5 | 15 | 165 |
| 69.0 | 27.7 | 2.8 | 2 | 4 | 14 | 153 |
| 44.4 | 44.4 | 11.1 | 2 | 4 | 12 | 121 |
| 25. | 50. | 25. | 2 | 4 | 12 | 119 |
| 11.1 | 44.4 | 44.4 | 4 | 8 | 18 | 171 |
| 2.8 | 27.7 | 69.0 | 10 | 17 | 40 | 393 |
| .03 | 9.0 | 90.7 | 36 | 68 | 166 | 1632 |
| .008 | 1.96 | 98.0 | 170 | 333 | 827 | 8243 |
| .000 | .09 | 99.9 | 3840 | 7653 | 19,111 | 191,002 |
+-----------+-----------+----------+--------+--------+--------+---------+
B: Where the new variety is recessive
+-----------+-----------+----------+------------------------------------+
| | | | Number of generations taken |
|Percentage |Percentage |Percentage| to pass from one position |
|of total |of total |of total | to another as indicated |
|population |population |population| in the percentages of different |
|formed by |formed by |formed by | individuals in left-hand column. |
|old variety|the hybrids|the new +--------+--------+--------+---------+
| | |variety | 100/50 | 100/75 | 100/90 | 100/99 |
+-----------+-----------+----------+--------+--------+--------+---------+
| 99.9 | .09 | .000 | | | | |
| 98.0 | 1.96 | .008 | 1920 | 5740 | 17,200 | 189,092 |
| 90.7 | 9.0 | .03 | 85 | 250 | 744 | 8,160 |
| 69.0 | 27.7 | 2.8 | 18 | 51 | 149 | 1,615 |
| 44.4 | 44.4 | 11.1 | 5 | 13 | 36 | 389 |
| 25. | 50. | 25. | 2 | 6 | 16 | 169 |
| 11.1 | 44.4 | 44.4 | 2 | 4 | 11 | 118 |
| 2.8 | 27.7 | 69.0 | 2 | 4 | 11 | 120 |
| .03 | 9.0 | 90.7 | 2 | 6 | 14 | 152 |
| .008 | 1.96 | 98.0 | 2 | 6 | 16 | 165 |
| .000 | .09 | 99.9 | 4 | 10 | 28 | 299 |
+-----------+-----------+----------+--------+--------+--------+---------+
{156}
If the favoured variety is dominant it must be borne in mind that it can be
either homozygous or heterozygous--that for these purposes it is
represented in the left-hand column by the hybrids as well as by the
homozygous dominant. In a population in equilibrium which contains about 2%
of a dominant form, the great bulk of these dominants will be heterozygous,
and the relative proportion of recessives, heterozygous, and homozygous
dominants is given in the second line of the left-hand column.
Let us suppose now that we want to know what will be the percentage of
dominants after 1000 generations if they form 2% of the population to start
with, and if, during this period, they have been favoured with a 1%
selection advantage. After 165 generations the proportion of recessives is
90.7, so that the proportion of dominants has risen to over 9%; after 153
further generations the percentage of dominants becomes 27.7 + 2.8 = 30.5;
after 739 generations it is 88.8%, and after 1122 generations it is 69.0 +
27.7 = 96.7. Hence the answer to our question will be between 89% and 97%,
but nearer to the latter figure than the former.
Mr Norton has informed me that the figures in the table are accurate to
within about 5%.
* * * * *
{157}
APPENDIX II
The genus _Papilio_ is a large and heterogeneous collection. It was pointed
out by Haase[93] that it falls into three distinct sections, of which
one--the Pharmacophagus section--provides those members which serve as
models in mimicry; while in the other two sections are found mimics, either
of Pharmacophagus Swallow-tails, or of models belonging to other groups.
Though Haase's terms have not yet come into general use with systematists,
there is little doubt that the genus _Papilio_ as it now stands must
eventually be broken up on these lines. To say that one species of
_Papilio_ mimics another is therefore somewhat misleading; for the
differences between the Pharmacophagus group and the other two are such as
to constitute at any rate generic distinction in other groups. For
convenience of reference a table has been added in which the various
Papilios mentioned in the text have been assigned to their appropriate
sections, and referred to their respective models. {158}
Pharmacophagus Papilio Cosmodesmus
(POISON-EATERS) (FLUTED SWALLOW-TAILS) (KITE SWALLOW-TAILS)
Antennae without Antennae without Antennae scaled
scales. scales. on upper side.
Outer ventral row Outer ventral row As in Papilio.
of spines of tarsi of spines of tarsi
not separated separated from
from the dorsal the dorsal spines
spines by a spineless by a spineless
longitudinal longitudinal depression.
depression.
Larva covered with Larva either smooth Larva with third
short hairs--with or with hard thoracic segment
fleshy tubercles spiny tubercles. enlarged
but no Third and fourth (known only in
spines. thoracic segments a few species).
enlarged.
Pupa with row of Pupa wrinkled--generally Pupa short with
well-marked with long four-sided
humps on each short dorsal thoracic horn.
side of abdomen. horn. Humps
if present very
short.
Larva feeds on Larva does not feed As in Papilio.
_Aristolochia_. on _Aristolochia_.
Abdominal margin Abdominal margin
of hind wing of hind wing
curved downwards bent over in [M],
forming and with scent
a kind of groove. organ in fold
No scent organ. so formed.
{159}
LIST OF PAPILIONINE MIMICS
----------------+-----------------+---------------+----------------------
PHARMACOPHAGUS | PAPILIO | COSMODESMUS |
(MODEL) | (MIMIC) | (MIMIC) | (MODELS)
----------------+-----------------+---------------+----------------------
ORIENTAL
|_agestor_ | |_Caduga tytia_
|_clytia_ | |_Danais septentrionis_
| " var. | |
| _dissimilis_| |_Euploea core_
|_mendax_ | | " _rhadamanthus_
|_paradoxus_ | | " _mulciber_
_hector_ |_polytes_ [F] | |
_aristolochiae_ | " [F] | |
_coon_ |_memnon_ [F] | |
_polyxenus_ |_bootes_ | |
|_laglaizei_ | |_Alcidis agathyrsus_
| |_delesserti_ |_Ideopsis daos_
| |_macareus_ |_Danais septentrionis_
| |_xenocles_ | " "
AFRICAN
|_dardanus_ [F] | |_Danais chrysippus_
| " [F] | |_Amauris niavius_
| " [F] | | " _echeria_
|_echerioides_ [F]| | " _psyttalea_
|_cynorta_ [F] | |_Planema epaea_
|_rex_ | |_Melinda formosa_
| |_ridleyanus_ |_Acraea egina_
| |_leonidas_ |_Danais petiverana_
| |_brasidas_ |_Amauris hyalites_
AMERICAN
_hahneli_(mimic)| | |_Methona confusa_
|_zagreus_ | |} various Heliconinae
|_bachus_ | |} and Ithomiinae
|_euterpinus_ | |_Heliconius melpomene_
| |_pausanias_ | " _sulphurea_
various species |_hippason_, etc. |_lysithous_ |
| | etc. |
_philenor_ |_troilus_ | |
|_turnus_ [F] | |
|_asterius_ [F] | |
* * * * *
{160}
PLATE I
ORIENTAL BUTTERFLIES
1. _Pareronia ceylonica_ [F] } (Pieridae)
2. " " [M] }
3. _Danais septentrionis_ (Danainae)
4. _Papilio xenocles_ (Papilionidae)
5. _Hypolimnas bolina_ [M] } (Nymphalinae)
6. " " [F] }
7. _Papilio clytia_ var. _dissimilis_ } (Papilionidae)
8. " " var. _lankeswara_ }
9. _Elymnias singhala_ (Satyrinae)
10. _Euploea core_ (Danainae)
[Illustration]
* * * * *
PLATE II
ORIENTAL BUTTERFLIES
1. _Delias eucharis_ (Pieridae)
2. _Caduga tytia_ (Danainae)
3. _Papilio agestor_ (Papilionidae)
4. _Euploea mulciber_ [M] } (Danainae)
5. " " [F] }
6. _Elymnias malelas_ [M] } (Satyrinae)
7. " " [F] }
8. _Euploea rhadamanthus_ (Danainae)
9. _Papilio mendax_ (Papilionidae)
[Illustration]
* * * * *
PLATE III
ORIENTAL MOTHS AND BUTTERFLIES
The three upper figures are those of moths, and the three lower ones are
those of butterflies.
1. _Alcidis agathyrsus_ (New Guinea)
2. _Papilio laglaizei_ " "
The moth is here supposed to serve as a model for the far rarer Papilio.
3. _Cyclosia hestinioides_
4. _Ideopsis daos_
The butterfly is very common and must be regarded as the model, the rarer
moth as the mimic.
5. _Epicopeia polydora_ (Assam)
6. _Papilio bootes_ "
Both of these species are to be regarded as mimics of the abundant
Pharmacophagus Papilio, _P. polyxenus_, which is very like _P. bootes_ in
appearance.
[Illustration]
* * * * *
PLATE IV
ORIENTAL BUTTERFLIES
1. _Danais chrysippus_ [M] } (Danainae)
2. " _plexippus_ [F] }
3. _Argynnis hyperbius_ [F] } (Nymphalinae)
4. " " [M] }
5. _Elymnias undularis_ [F] } (Satyrinae)
6. " " [M] }
7. _Hypolimnas misippus_ [F] } (Nymphalinae)
8. " " [M] }
The two Danaids together with the females of the other three species form a
"mimicry ring." For explanation see text, pp. 65-69.
[Illustration]
* * * * *
PLATE V
ORIENTAL BUTTERFLIES
1. _Papilio polytes_ [M]
2. " " [F], var. _cyrus_ (M form)
3. " " [F], var. _polytes_ (A form)
4. " " [F], var. _romulus_ (H form)
5. " _aristolochiae_
6. " _hector_
The specimens figured on this plate were taken in Ceylon where they are all
plentiful.
Figures 1_a_--6_a_ represent the under surfaces of the hind wings belonging
to specimens 1--6.
[Illustration]
* * * * *
PLATE VI
AFRICAN BUTTERFLIES
(except _A. levana_, Figs. 8--10, which is European)
1. _Danais petiverana_ (Danainae)
2. _Papilio leonidas_ (Papilionidae)
3. _Amauris hyalites_ (Danainae)
4. _Papilio leonidas_ var. _brasidas_ (Papilionidae)
5. _Pseudacraea boisduvali_ (Nymphalinae)
6. _Papilio ridleyanus_ (Papilionidae)
7. _Acraea egina_ (Acraeinae)
8. _Araschnia levana_ var. _porima_
9. " " var. _prorsa_
10. " "
11. _Precis octavia_ var. _sesamus_
12. " " var. _natalensis_
[Illustration]
* * * * *
PLATE VII
TROPICAL AFRICAN BUTTERFLIES
1. _Planema macarista_ [M] (Acraeinae)
2. " " [F] "
3. " _tellus_ "
4. " _paragea_ "
5. " _epaea_ "
6. _Pseudacraea hobleyi_ [M] (Nymphalinae)
7. " " [F] "
8. " _terra_ "
9. _Elymnias phegea_ [F] (Satyrinae)
10. _Papilio cynorta_ [F] (Papilionidae)
(NOTE. _Pseudacraea hobleyi_ and _P. terra_ (Figs. 6--8) were at one time
regarded as separate species. More recently they have been shewn to be
forms of the polymorphic species, _Pseudacraea eurytus_.)
[Illustration]
* * * * *
PLATE VIII
AFRICAN BUTTERFLIES
1. _Papilio dardanus_ [M]
2. " " [F], var. _trophonius_
3. " " [F], var. _hippocoon_
4. " " [F], var. _cenea_
5. _Danais chrysippus_ (Danainae)
6. _Amauris niavius_ "
7. " _echeria_ "
8. _Hypolimnas dubius_ var. _mima_ (Nymphalinae)
9. " " var. _wahlbergi_ "
[Illustration]
* * * * *
[Illustration]
_Danais chrysippus_
a. Typical form
b. _Alcippus_ form
c. _Dorippus_ form
_Acraea encedon_
d. Typical form
e. _Alcippina_ form
f. _Daira_ form
_Hypolimnas misippus_ [F]
g. Typical form
h. _Alcippoides_ form
i. _Inaria_ form
(After Aurivillius)
* * * * *
PLATE X
SOUTH AMERICAN BUTTERFLIES
1. _Dismorphia cretacea_ [M] (Pieridae)
2. " _praxinoe_ [M] "
3. " " [F] "
4. _Perrhybris malenka_ [M] "
5. " " [M] (under surface) "
6. " " [F] "
7. _Mechanitis saturata_ (Ithomiinae)
8. _Papilio zagreus_ (Papilionidae)
9. _Protogonius tithoreides_ (Nymphalinae)
10. _Tithorea pseudonyma_ (Ithomiinae)
(NOTE. The figure of the _Mechanitis_ (Fig. 7) is taken from a rather worn
specimen. The quality of the orange brown is better shewn by the specimen
illustrated in Fig. 7 on Plate XV.)
[Illustration]
* * * * *
PLATE XI
SOUTH AMERICAN BUTTERFLIES
1. _Heliconius sulphurea_ (Heliconinae)
2. _Papilio pausanias_ (Papilionidae)
3. _Heliconius telesiphe_ (Heliconinae)
4. _Colaenis telesiphe_ (Nymphalinae)
5. _Heliconius melpomene_ (Heliconinae)
6. _Pereute charops_ [F] (Pieridae)
7. " " [M] "
8. _Papilio osyris_ [M] (Papilionidae)
9. " " [F] "
10. _Archonias critias_ [F] (Pieridae)
[Illustration]
* * * * *
[Illustration]
PLATE XII
SOUTH AMERICAN BUTTERFLIES
_Methona confusa_ (Ithomiinae)
_Dismorphia orise_ (Pierinae)
_Ituna phenarete_ (Danainae)
_Castnia sp._ (Heterocera)
* * * * *
[Illustration]
PLATE XIII
MODELS
1. _Papilio nephalion_
2. " _chamissonia_
3. " _perrhebus_
MIMICS
4. _Papilio lysithous_ var. _lysithous_
5. " " var. _rurik_
6. " " var. _pomponius_
(For further details of this case see Jordan, _I^{er} Congr. Internat.
d'Entomologie_, Bruxelles, 1911, p. 396.)
* * * * *
[Illustration]
PLATE XIV
1. _Methona confusa_, ×90 (Ithomiinae)
2. _Dismorphia orise_, ×150 (Pierinae)
3. _Thyridia themisto_, ×90 (Ithomiinae)
4. _Ituna ilione_, ×90 (Danainae)
5. _Castnia sp._, ×60 (Moth)
Microphotographs of the scales of various Lepidoptera in the S. American
"Transparency group." For explanation see text, pp. 39-42.
* * * * *
PLATE XV
CENTRAL AND SOUTH AMERICAN BUTTERFLIES
Illustrating the closely parallel series of patterns occurring in the two
distinct groups Heliconinae and Ithomiinae.
1. _Heliconius mirus_
2. " _telchinia_
3. " _eucrate_
4. " _pardalinus_
5. " _splendens_
6. _Mechanitis elisa_
7. " _saturata_
8. " _lysimnia_
9. " _egaensis_
10. " _methona_
[Illustration]
* * * * *
PLATE XVI
NORTH AMERICAN BUTTERFLIES
1. _Papilio philenor_ (Papilionidae)
2. " _troilus_ "
3. _Argynnis diana_ [F] (Nymphalinae)
4. _Limenitis arthemis_ "
5. " _astyanax_ "
6. " _archippus_ "
7. " _floridensis_ (= _eros_) "
8. _Danais archippus_ (Danainae)
9. " _berenice_ "
[Illustration]
* * * * *
{183}
INDEX
_References to the plates are given in thicker type_
_Acraea_, taken by kestrel, 118;
_A. axina_, 122;
_A. caldarena_, 122;
_A. egina_, 34, VI. 7;
_A. encedon_, patterns of different forms in relation to those of
_Danais chrysippus_, 29, 144;
typical form of, IX. D;
_alcippina_ form of, IX. E;
_daira_ form of, IX. F;
_A. halali_, 122;
_A. violae_, 33 note;
eaten by lizards, 108;
attacked by birds, 110, 117
Acraeinae, as models for African butterflies, 33
Adaptation and Natural Selection, 61
_Adelpha_, 54
African butterflies, mimicry among, 28-36
_Alcidis agathyrsus_, 27, 145, III. 1
_Aletis helcita_, 36
_Amauris echeria_, 30, 148, VIII. 7;
_A. hyalites_, 30, VI. 2;
_A. niavius_, 30, VIII. 6
_Amphidasys betularia_, rapidity of increase in melanic sport of, 101
_Anosia plexippus_ (= _Danais archippus_), 113
_Anthomysa_, 41
_Aporia agathon_, 149
_Araschnia levana_, seasonal dimorphism in, 130;
typical form, VI. 10;
_prorsa_ form, VI. 9;
_porima_ form, VI. 8
_Archonias_, 43, 56, 145;
_A. critias_, XI. 10
_Argynnis diana_, 47, XVI. 3;
_A. hyperbius_, 29;
as mimic of _Danais plexippus_, 52;
in mimicry ring, 66, IV. 3, 4
_Artamus fuscus_, 112
Asilid flies, as enemies of butterflies, 106
_Athyma punctata_, 53
Bates, G. L., on contents of birds' stomachs, 113
Bates, H. W., on mimicry, 9;
on resemblances between unpalatable forms, 14;
on initial variation in mimetic resemblance, 63;
on S. American Pierines attacked by birds, 112
Bateson, 3
_Belenois_, 36
Bingham, on birds eating butterflies, 110
Birds, as enemies of butterflies, 109;
stomach contents of, 113;
feeding experiments with, 115;
colour perception in, 119
Bowater, on _Amphidasys betularia_, 102, 137 note
Breeding experiments, with _Hypolimnas dubius_, 30;
with _Papilio polytes_, 84;
with _Papilio memnon_, 89;
with _Papilio dardanus_, 90;
with _Pseudacraea eurytus_, 128
Bryant, on birds eating butterflies, 114
_Buchanga atra_, 111
_Byblia ilithyia_, 122
{184}
_Caduga tytia_, 24, 51, II. 2
_Callamesia pieridoides_, 56
_Calotes ophiomachus_, 107;
_C. versicolor_, 107
Carpenter, on intermediates in _Pseudacraea eurytus_, 126;
on breeding experiments with _Pseudacraea eurytus_, 128
_Castnia_, as mimic, 39, XII. 4;
scales of, 41, XV. 5
_Catopsilia_, 121;
_C. florella_, 111;
_C. pyranthe_, 111
_Cerchneis rupicoloides_, 118;
_C. naumanni_, 117
_Cercopithecus pygerythrus_, 121
_Charaxes athamas_, 110
_Citronophila similis_, 35
Classification of butterflies, 18-21
_Colaenis telesiphe_, 38, XI. 4
_Cyclosia hestinioides_, III. 3
_Cymatophora or_, establishment of melanic sport in, 102 note
_Cyrestis thyodamas_, 110
Danainae, characteristics of, 22;
as models for Oriental butterflies,23;
as models for African butterflies, 28
_Danais_, 111, 145;
_D. archippus_, 48;
eaten by lizard, 108;
rejected by bird, 113, XVI. 8;
_D. berenice_, 48, XVI. 9;
_D. chrysippus_, 23, 28;
flight of, 55;
in mimicry ring, 65;
eaten by lizards, 108;
eaten by Bee-eater, 111;
eaten by Brown Shrike, 117;
rejected by Kestrel, 118;
rejected by baboon, 122;
local variation in, 132;
patterns overlapping with those of _Acraea encedon_, 144;
_alcippus_ form, IX. B;
_dorippus_ form, IX. C;
typical form, IV. 1, VIII. 5;
_D. plexippus_, as model for _Argynnis hyperbius_, 52;
in mimicry ring, 65;
eaten by Liothrix, 115 note, IV. 2;
_D. petiverana_, 29, VI. 1;
_D. septentrionis_, 23, 111, 112, I. 3;
_D. vulgaris_, 150
Darwin, on natural selection, 1;
on adaptation, 5;
on initial variation in mimetic resemblance, 63;
on a difficulty of the mimicry theory, 65
Defence in butterflies, 54
_Delias cathara_, 56;
_D. eucharis_, 28, 115, 116, II. 1
de Meijere, on breeding _Papilio memnon_, 89
de Vries, 3
_Dismorphia_, as mimics of Ithomiinae, 38, 42;
restricted range of many forms, 51;
diversity of pattern in genus, 58;
as Batesian mimics, 135;
patterns parallel with those of Ithomiinae, 145;
_D. astynome_, 151;
_D. avonia_, 151;
_D. cretacea_, 5, 8, 62, X. 1;
_D. orise_, as mimic, 39, XII. 2;
scales of, 40, XIV. 2;
_D. praxinoe_, as mimic, 57, 62, X. 2, 3;
as member of mimicry ring, 134
Distasteful groups, characteristics of, 55
Eltringham, 17 note, 32 note, 36 note
_Elymnias_, patterns in genus compared with those of Danaidae, 59, 144;
_E. malelas_, 24, II. 6, 7;
_E. phegea_, 35, VII. 9;
_E. singhala_, 25, I. 9;
_E. undularis_, in mimicry ring, 66, 115 note, 116, IV. 5, 6
_Epicopeia polydora_, 27, III. 5
Equilibrium, conditions of in mixed population, 93
_Eresia_, 134, 135
_Eugonia californica_, 114
_Euphaedra ruspina_, 36
_Euploea core_, 25, 108, 110, 112, I. 10;
_E. mulciber_, 24, 51, II. 4, 5;
_E. rhadamanthus_, 24, 51, II. 8;
_E. rafflesii_, 110
Euploeinae, characteristics of, 22;
as models for Oriental butterflies, 24;
in relation to birds, 111, 112, 115 note
{185}
_Euripus halitherses_, 24
Feeding experiments, with Mantids, 105;
with lizards, 107;
with birds, 115;
with mammals, 121
Finn, on feeding experiments with lizards, 108;
on feeding experiments with Indian birds, 115;
on feeding experiments with a Tree-shrew, 121
Flight, different in model and mimic, 55;
difference of in _Papilio polytes_ and its models, 82
Fryer, on breeding _Papilio polytes_, 84;
on relative abundance of females of_ Papilio polytes_ in Ceylon, 97;
on birds eating "unpalatable" butterflies, 112
_Gerrhonotus infernalis_, 108
Haase, on mimicry, 16;
on classification of Papilionidae, 25
Hahnel, on S. American Pierines attacked by birds, 112
Hardy, on conditions of equilibrium in a mixed population, 94
Hearsy, on birds eating butterflies, 111
_Hebomoia_, 110
Heliconinae, as models for S. American butterflies, 38
_Heliconius_, 145;
_H. eucrate_, XV. 3;
_H. melpomene_, as model, 42, 43, XI. 5;
_H. mirus_, XV. 1;
_H. pardalinus_, XV. 4;
_H. splendens_, XV. 5;
_H. sulphurea_, 43, XI. 1;
_H. telchinia_, XV. 2;
_H. telesiphe_, XI. 3
_Herpestes galera_, 121
Hess, on colour perception in birds, 119
Hopkins, on pigment of Pierids, 150
_Hypolimnas dubius_, polymorphism in, 30;
as mimic of Danaines,30, VII. 8, 9;
breeding experiments with, 30;
var. _mima_ compared with model, 148;
patterns of in relation to models, 149;
_H. bolina_, 25, 117, I. 5, 6;
_H. misippus_, 25, 29,
as model, 53;
flight of, 55;
in mimicry ring, 66, 116;
eaten by Brown Shrike, 117;
_alcippoides_ form, IX. H;
_inaria_ form, IX. I;
typical form, IV. 7, 8, IX. G
_Ideopsis daos_, III. 4
Initial variation, difficulty of, 63
Insect enemies of butterflies, 105
Intermediates, between different forms of _Pseudacraea eurytus_, 128;
in relation to mimicry,129, 140
Ithomiinae, characteristics of, 10;
as models for S. American butterflies, 38
_Ituna_, 39;
_I. ilione_, 40, XIV. 4;
_I. phenarete_, XII. 3
Jacobsen, experiments with _Papilio memnon_, 89
Jordan, 40 note
_Junonia_, 111
_Lanius cristatus_, 117
_Limenitis albomaculata_, 53;
_L. archippus_, 49, 59, XVI. 6;
_L. arthemis_, 47, 49, XVI. 4;
_L. astyanax_, 47, XVI. 5;
_L. floridensis (= eros)_, 49, XVI. 7;
_L. proserpina_, 47
Lizards, as enemies of butterflies, 107
Local varieties, in connection with mimicry, 132
Lycaenidae, as mimics in Africa, 35
_Lycorea_, 145
McAtee, on feeding experiments with birds, 118
Mammals, as enemies of butterflies, 121
Manders, on feeding experiments with lizards, 107;
with birds, 117
{186}
Mantids, as enemies of butterflies, 105
Marshall, on Müllerian mimicry, 72;
on feeding experiments with Mantids, 105;
on birds as enemies of butterflies, 107;
on feeding experiments with S. African birds, 117;
with monkeys, 121;
on birds attacking Pierids, 150
_Mechanitis egaensis_, XV. 9;
_M. elisa_, XV. 6;
_M. lysimnia_, 151, XV. 8;
_M. methona_, XV. 10;
_M. saturata_, as model for _Dismorphia praxinoe_, 57, 62;
as member of mimicry ring, 134, XV. 7
Melanic sports in moths, 101
_Melinaea_, 135
_Melinda formosa_, App. II
_Melittophagus swinhoei_, 110
_Merops viridis_, 111
Merrifield, on seasonal dimorphism, 130
_Methona confusa_, XII. 1, XIV. 1
Migratory birds, suggested influence on mimicry of, 53
_Mimacraea_, 35
Mimetic resemblance, as induced through gradual slight changes, 64
Mimic, occupying same station as model, 51;
occupying station apart from model, 53;
scarcer than model, 56;
pattern of in relation to allies, 57
Mimicry, Wallace's conditions of, 50;
Batesian, 9;
Müllerian, 14
Mimicry rings, 65;
in S. American butterflies, 134;
and natural selection, 136
Mimicry theory, difficulties of, 139
Monkeys, as enemies of butterflies, 121
Moths, mimicry in, 27, 36
Moulton, on S. American mimicry rings, 134
Müller, 14, 72
Müllerian mimicry, 53, 57, 66;
difficulties of, 72
Mutation, see Sports
_Mylothris_, 36
Natural selection and mimicry, 10-12, 61, 92, 152
Neal, on monkeys as enemies of butterflies, 123
_Nepheronia (= Pareronia) hippia_, 116
_Neptis imitans_, 24;
_N. nemetes_, 54;
_N. kamarupa_, 121
North American butterflies, mimicry among, 45
Norton, on rapidity of changes in mixed populations through natural
selection, 94, App. I
Oriental butterflies, mimicry among, 23
Overlapping in patterns of different groups of butterflies, 144
_Papilio aristolochiae_, as model for female of _P. polytes_, 13, 26, 52,
77;
range of, 79;
likeness to _P. polytes_, 80;
characteristics of, 81;
flight of, 82;
eaten by lizards, 108;
rejected by certain birds, 115, 116;
disliked by Tree-shrew, 121, V. 5, 5A;
_P. agestor_, 24, 51, II. 3;
_P. asterius_, 46;
_P. bachus_, App. II;
_P. bootes_, 27, III. 6;
_P. brasidas_, 29, VI. 4;
_P. chamissonia_, 44, XIII. 2;
_P. clytia_, 23, 25, 55, I. 7, 8;
_P. coon_, 26, 89;
_P. cynorta_, 35, 36, VII. 10;
_P. dardanus_, investigated by Trimen, 14;
mimicry in, 30;
breeding experiments with, 90;
polymorphic forms of in relation to models, 149 note;
var. _humbloti_, 32;
var. _meriones_, 32;
[F] _cenea_, 31, VIII. 4;
[F] _dionysus_, 31, 33;
[F] _hippocoon_, 31, VIII. 3;
[F] _niavioides_, 32, 33;
[F] _planemoides_, 31;
[F] _ruspina_, 33;
[F] _trimeni_, 31, 32, 33;
{187}
[F] _trophonius_, 31, 122, VIII. 2;
_P. delesserti_, App. II;
_P. demoleus_, 111, 121;
_P. echerioides_, App. II;
_P. erithonius_, 110;
_P. euterpinus_, 42, 43;
_P. glaucus_, 45;
var. _turnus_, 46;
_P. hahneli_, 39;
_P. hector_, model for female of _P. polytes_, 13, 52, 78;
range of, 79;
characteristics of, 81;
flight of, 82;
eaten by lizards, 108;
eaten by birds, 110, 117, V. 6, 6A;
_P. hippason_, App. II;
_P. laglaizei_, 27, 124, III. 2;
_P. leonidas_, 29, VI. 3;
_P. lysithous_, polymorphism in, 44;
[F] _lysithous_, XIII. 4;
[F] _rurik_, XIII. 5;
[F] _pomponius_, XIII. 6;
_P. macareus_, 23, 111;
_P. memnon_, 26, 89;
_P. mendax_, 24, 51, II. 9;
_P. nephalion_, 44, XIII. 1;
_P. osyris_, XI. 8, 9;
_P. paradoxus_, 25;
_P. pausanias_, 43, XI. 2;
_P. perrhebus_, 44, XIII. 3;
_P. philenor_, as model, 45;
taken by lizard, 108, XVI. 1;
_P. polytes_, polymorphism in females of, 13, 75;
mimic of Pharmacophagus Papilio, 26;
habits of, 52, 124;
often more abundant than models, 56;
description of, 76-78;
relative abundance of models in Ceylon, 79;
breeding experiments with, 84;
equilibrium among females of in Ceylon, 96;
relative abundance of three forms of female of in Ceylon, 97;
historical notes on abundance of forms of female in Ceylon, 98;
origin of forms of female in, 125, 141;
relation of polymorphic forms to models in, 149 note;
preyed on by Wood-Swallow, 112;
feeding experiments with, 116, V. 1-4, 1A-4A;
_P. polyxenus_, 27;
_P. rex_, App. II;
_P. ridleyanus_, 34, 36, VI. 6;
_P. sarpedon_, 110;
_P. troilus_, 45, XVI. 2;
_P. xenocles_, 23, 111, I. 4;
_P. zagreus_, 43, X. 8
Papilionidae, as mimics of Oriental models, 23-25;
of African models, 29, 30, 35;
of S. American models, 43;
of N. American models, 45
Parallel patterns, in different butterfly groups, 144
_Pareronia_, 145, 149;
_P. ceylanica_, 23, 59, 116 note, I. 1, 2
Pattern and physiological properties, possible connection between, 137
Patterns, overlapping series of in different groups of butterflies, 145
_Pedaliodes_, 135
_Pereute charops_, 42, XI. 6, 7
_Pericopis_, 39
_Perrhybris_, as mimics of Ithomiines, coloration of male in _P.
malenka_, 62;
as members of mimicry rings, 134, 135;
_P. demophile_, 151;
_P. lorena_, 151;
_P. malenka_, X. 4, 5, 6
Pharmacophagus Swallow-tails, characteristics of, 22, App. II;
as models for Oriental butterflies, 25;
absence of in Africa, 35;
as models in S. America, 43;
as models in N. America, 45
_Phrissura_, 36
_Phyciodes_, 38, 54
Physiological properties, possible connection of with pattern, 137
Pieridae, as models for Oriental butterflies, 28;
mimicry in African, 36;
mimicry in S. American, 43;
frequency of bird attacks on, 150
_Planema epaea_, 35, VII. 5;
_P. macarista_, sexual difference in, 34, VII. 1, 2;
mimicked by _Elymnias phegea_, 35;
by _Pseudacraea eurytus_, 126;
_P. poggei_, as model for _planemoides_ female of _Papilio dardanus_,
31;
_P. paragea_, 126, VII. 4;
_P. tellus_, 126, VII. 3
{188}
Poison-eaters, see Pharmacophagus Swallow-tails
Polymorphism, in females of mimicking species, 13;
among females of _P. dardanus_, 30;
among females of _P. polytes_, 75
Population, conditions of equilibrium in mixed, 93
Poulton, 17;
on N. American mimetic butterflies, 45;
on the "Transparency group," 41;
on mimicry through agency of migratory birds, 53;
on _Hypolimnas misippus_, 66 note;
on the relation between mimetic forms of _P. polytes_, 90;
on predaceous insects, 105;
on relative proportion of different forms of _Pseudacraea eurytus_,
127;
on local variation in _D. chrysippus_, 132
_Precis_, 111, 122, 131;
_P. octavia_, seasonal dimorphism in, 131, VI. 11, 12
_Prioneris_, 110;
_P. sita_, 28
Pritchett, feeding experiments with lizards, 108
Protective resemblance, 8
_Protogonius_, as mimics of Ithomiines, 38;
as members of mimicry rings, 134, 135, 138;
_P. tithoreides_, X. 9
_Pseudacraea_, 59, 144;
_P. boisduvali_, 34, VI. 5;
_P. eurytus_, relative proportion of different forms in, 127;
polymorphism of in relation to model, 149 note;
var. _hobleyi_ as mimic of _Planema macarista_, 35, 127, VII. 6, 7;
var. _terra_, as mimic of _Planema tellus_, 126, VII. 8;
var. _obscura_ as mimic of _Planema paragea_, 126
Ray, on adaptation, 4, 6
Rodents, bearing on mimicry of recent genetic work with, 147
Satyrinae, transparency in S. American, 42
_Sceleporus floridanus_, 108
Schaus, on birds as enemies of butterflies, 112
Seasonal dimorphism, 130
Seitz, 44, 52, 58
Shelford, 56 note
S. American butterflies, mimicry among, 38
Sports, as foundation of mimetic resemblances, 70, 91, 143
Sweet-peas, experiments on, 91
Swynnerton, on contents of stomachs of birds, 114
_Telipna sanguinea_, 36
_Terias brigitta_, 35;
_T. hecabe_, 110
_Thyridia_, 40, XIV. 3
_Tithorea pseudonyma_, X. 10
"Transparency group," in S. America, 39
Trimen, on mimicry in African butterflies, 13
_Tupaia ferruginea_, 121
Variation, difficulty of initial, 63
Wade, on relative abundance of the three forms of _P. polytes_ in Ceylon,
99
Wallace, on mimicry in Oriental butterflies, 12;
on the conditions of mimicry, 50;
on the females of _P. polytes_, 76;
on initial variation, 64
Warning colours, 10, 11
Weismann, 1, 2
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NOTES
[1] _The Wisdom of God manifested in the Works of the Creation_, London,
1691.
[2] Ray gives the case of an elephant "that was observed always when he
slept to keep his trunk so close to the ground, that nothing but Air could
get in between them," and explains it as an adaptation in habit to prevent
the mice from crawling into its lungs--"a strange sagacity and Providence
in this Animal, or else an admirable instinct."
[3] _Trans. Linn. Soc._ vol. 23, 1862.
[4] _Trans. Linn. Soc._ vol. 25, 1866.
[5] _Trans. Linn. Soc._ vol. 26, 1870.
[6] In attributing this quality to the butterflies in question I am merely
stating what is held by the supporters of the mimicry theory. I know of
scarcely any evidence either for or against the supposition.
[7] It is assumed that the intelligence of the birds is such that they can
learn a pattern after a single disagreeable experience of it.
[8] _Untersuchungen über die Mimikry_, 1893.
[9] The African mimetic butterflies have been recently monographed by
Eltringham in a large and beautifully illustrated work--_African Mimetic
Butterflies_, Oxford, 1910.
[10] Omitting the Hesperidae which hardly enter into questions of mimicry.
[11] The classification adopted is that used by Dr Sharp in the "Cambridge
Natural History," _Insects_, vol. 2, 1901.
[12] Cf. Shelford, _Proc. Zool. Soc._ 1902.
[13] _African Mimetic Butterflies_, Oxford, 1910.
[14] These African species of _Hypolimnas_ are frequently referred to the
genus _Euralia_.
[15] Corresponding to the _dorippus_ form of _D. chrysippus_ (cf. Pl. IX)
there is a rare form of _trophonius_ known as _dorippoides_.
[16] These two forms are figured on Plate 10 of Eltringham's _African
Mimetic Butterflies_.
[17] _Acraea violae_, the only representative of the group in S. India and
Ceylon, is nevertheless a very abundant insect. It cannot, however, be said
that it is definitely mimicked by any other species in this region.
[18] Coloured figures of these and of the other African species referred to
may be found in Eltringham's work on _African Mimetic Butterflies_.
[19] These descriptions are taken from preserved specimens which I owe for
the most part to the kindness of Dr Jordan. I have not had an opportunity
of examining fresh ones.
[20] This is more marked in _Castnia_ than in _Anthomysa_. It appears to be
a peculiarity of many members of the genus _Castnia_ that the scales do not
lie so tight as generally in moths. Owing to this, some of the large
whole-coloured species have a somewhat fluffy look.
[21] Cf. Poulton, _Essays on Evolution_, 1908, pp. 264-6.
[22] Cf. Poulton, _Darwin and the 'Origin,'_ 1909, pp. 177-186.
[23] The N. American members of this genus are often referred to as
_Basilarchia_.
[24] _Darwinism_, 1890 (1st Edition 1889), p. 264.
[25] _Macrolepidoptera of the World._ _Fauna Americana_, p. 98.
[26] _Essays on Evolution_, 1908, p. 381.
[27] These "unpalatable" butterflies are sometimes extensively preyed upon
by insectivorous birds, when they fall an easier prey owing to their
slowness (cf. p. 112).
[28] See Shelford, PROC. ZOOL. SOC. 1902, p. 260. A coloured figure of both
species is given in the paper.
[29] _Macrolepidoptera of the World._ _Fauna Americana_, pp. 98-104, Plates
28-30.
[30] "In what way our _Leptalis_ (= _Dismorphia_) originally acquired the
general form and colour of Ithomiae I must leave undiscovered." _Trans.
Linn. Soc._ vol. 23, 1862, p. 513.
[31] _Darwinism_, 1890, pp. 242-244.
[32] _Origin of Species_, 6th Edition, 1891, p. 354.
[33] _H. misippus_ was at one time regarded as a clear case of Batesian
mimicry. But in view of its plentifulness, of the fact that it may be
abundant outside the area inhabited by its model, and of the ease with
which it can establish itself in parts remote from its original habitat,
_e.g._ S. America, it has come to be regarded by certain supporters of the
mimicry theory as a Müllerian mimic. Cf. Poulton, _Essays on Evolution_,
1908, pp. 215-217.
[34] An English translation of Müller's paper is given by Meldola, _Proc.
Ent. Soc._, 1879, p. xx.
[35] _Trans. Ent. Soc. Lond._, 1908, p. 93.
[36] Provided of course that the type form remains in the majority. If the
variation occurred simultaneously in more than 50% of A the advantage would
naturally be with the variation.
[37] It is possible to imagine an exceptional case though most unlikely
that it would occur. Suppose for example that there were a number of
distasteful species, say 20, all of different patterns, and suppose that in
all of them a particular variation occurred simultaneously; then if the
total shewing that variation from among the 20 species were greater than
the number of any one of the species, all of the 20 species would come to
take on the form of the new variation. In this way it is imaginable that
the new pattern would gradually engulf all the old ones.
[38] _Trans. Linn. Soc._ vol. 24, 1866.
[39] These darker ribs are also present in the male and M female but are
obscured owing to the generally deeper colour.
[40] See Appendix II, p. 158.
[41] _Spolia Zeylanica_, 1910.
[42] We shall take it for the present that, from the point of view of
mimicry, birds are the main enemies of butterflies (cf. Chap. IX).
[43] See later, p. 119.
[44] The specimens figured on Pl. V were dried in papers when taken. The
body is consequently much compressed and the characteristic scarlet of _P.
hector_ and _P. aristolochiae_ is largely hidden.
[45] _Philosophical Transactions of the Royal Society_, vol. 204, 1913.
[46] _Tijdschr. voor Entomologie_, vol. 53, 1909. A more accessible account
is given by de Meijere, _Zeit. f. indukt. Abstamm. u. Vererbungslehre_,
vol. 3, 1910.
[47] For further information see Poulton, _Trans. Ent. Soc. Lond._ 1909,
and various notes in _Proc. Ent. Soc. Lond._ subsequent to this date.
[48] _Science_, July, 1908.
[49] If for example there were 5000 dominants and 4000 recessives, and if
only half of the population survives to mate, then we should be left with
2500 dominants and 2000 recessives as parents of the next generation. But
if there were also a 10% selective disadvantage working against the
recessives, their numbers would be further reduced from 2000 to 1800 and
the proportion of dominants to recessives would be changed from 5:4 to
25:18.
[50] As these larvae were for the most part found simply over a
considerable time it follows that they are the offspring of different
females and represent the relative proportions of the three forms in the
general population.
[51] _The Lepidoptera of Ceylon_, 1880.
[52] From the experience of breeders it would appear that the melanic form
is somewhat hardier, at any rate in captivity.
[53] Intermediates may also occur in some strains (cf. Bowater, _Journal of
Genetics_, vol. 3, no. 4, 1914).
[54] An interesting case of a similar nature has recently been published by
Hasebroek (_Die Umschau_, 1913, p. 1020). A melanic form of the moth,
_Cymatophora or_, suddenly appeared near Hamburg in 1904. This new form, to
which the name _albingensis_ was given, rapidly became the predominant one.
In 1911-1912 over 90% of the moths reared from caterpillars taken in the
open were of the _albingensis_ form; nor were any intermediates found
between it and the typical form. Some experiments were also made which shew
that the _albingensis_ form behaves as a dominant to the original type
form.
[55] _Trans. Ent. Soc. Lond. 1907._
[56] _Trans. Ent. Soc. Lond. 1902._
[57] _Proc. Zool. Soc._ 1911.
[58] _Journ. Roy. Asiat. Soc. Bengal_, vol. 65, 1897.
[59] _Spolia Zeylanica_, 1910.
[60] _Biological Bulletin_, vol. 5, 1903.
[61] _Trans. Ent. Soc. Lond._ 1909.
[62] _Trans. Ent. Soc. Lond._ 1902.
[63] _Trans. Ent. Soc. Lond._ 1911.
[64] _Proc. Zool. Soc. 1913._
[65] _A Naturalist in Nicaragua_, 1874, p. 316.
[66] _I^{er} Congr. Internat, d'Entomologie_, Bruxelles, 1911.
[67] _Ibis_, 1911.
[68] _Ibis_, 1912.
[69] _The Condor_, vol. 13, 1911, pp. 195-208.
[70] _Journ. Asiat. Soc. Bengal_, vol. 64, 1895, and vol. 66, 1897.
[71] Nevertheless a Liothrix is recorded as eating _Danais plexippus_ and a
_Euploea_ even though two male specimens of the palatable _Elymnias
undularis_ were in the cage.
[72] A form closely resembling _P. ceylonica_ figured on Pl. I, fig. 1.
[73] _Proc. Zool. Soc. Lond. 1911._
[74] _Proc. Acad. Nat. Sci. Philadelphia_, 1912.
[75] C. Hess, _Handbuch der vergleichenden Physiologie_ (herausgegeben von
H. Winterstein), Bd. 4, 1912, p. 563.
[76] _Journ. As. Soc. Bengal_, vol. 66^2, 1898.
[77] _Trans. Ent. Soc. Lond._ 1902.
[78] Marshall, _loc. cit._ p. 379.
[79] In this connection may be quoted a letter from Capt. N. V. Neal near
Lagos to Mr W. A. Lamborn which was recently published in the _Proceedings
of the Entomological Society_.
"You have asked me about monkeys eating butterflies. This is very common,
as every native will tell you. I have seen it myself. The monkey runs along
a path, sees some butterflies fluttering round some filth, goes very
quietly, and seizes one by the wings, puts the solid part (body) into his
mouth, then pulls the wings off. The poor butterfly goes down like any
oyster.... The dog-faced baboon and the large brown monkey with a very long
tail, which seems to be the most common species in this colony, are great
butterfly-eaters. The little spider-monkey also considers a butterfly a
treat, and prefers one to a spider."
[80] Cf. E. B. Poulton in _Bedrock_ for Oct. 1913, p. 301.
[81] _Trans. Ent. Soc. London, 1914._
[82] In the female _hobleyi_, with rare exceptions, the orange of the male
is replaced by white, and it has received the name _tirikensis_. The female
of _P. macarista_ also shews white in place of the orange of the male.
[83] Cf. Poulton, E. B., _I^{er} Congr. Internat. d'Entomol._, Bruxelles
1911. This proportion is founded on several hundreds caught at random.
Observers are agreed that _Pseudacraea_ is both a warier insect and a
stronger flyer than the various Planemas which it resembles.
[84] _I^{er} Congr. Internat. d'Entom._, Bruxelles 1911.
[85] Cf. Poulton, _Bedrock_, Oct. 1913, p. 300.
[86] The size of the white spot may shew much variation in specimens from
the same region. I have seen African specimens in which it is large, while
in the Ceylon specimen figured on Plate IV it is as small as in the typical
African specimen shewn on Plate VIII.
[87] See Moulton, J. C., _Trans. Ent. Soc. London_, 1909.
[88] In this connection it is of interest that a recent observer with
considerable breeding experience finds that the dark _doubledayaria_
variety of the Peppered Moth is more hardy than the typical form (cf. p.
101). The swift success of the dark variety led some to regard it as better
protected against bird enemies. It is, however, not unlikely that the
deeper pigmentation is associated with some physiological difference which
makes for greater hardiness. See Bowater, _Journal of Genetics_, vol. 3,
1914.
[89] As examples may be mentioned _P. polytes_, _Hypolimnas misippus_, _H.
dubius_, and _Pseudacraea hobleyi_. With the exception of the _planemoides_
form it is true also for _P. dardanus_, the most polymorphic of them all.
[90] _Trans. Ent. Soc. Lond. 1909._
[91] Cf. F. G. Hopkins, _Phil. Trans. Roy. Soc. 1895._
[92] Coloured representations of these two species will be found on Pl. 20
of Seitz, _Macrolepidoptera of the World, Fauna Americana_.
[93] _Untersuchungen über die Mimikry_, 1893.