of this essay, the external conditions remain unaltered during the
lifetime of the caterpillar, but change of habit, and in some cases
of colour, occurs when the insect has attained a size conceivable _à
priori_, and are realized by observation, in which the environment
itself may undergo change during the lifetime of the individual
caterpillar. Thus, in the case of hibernating species, the colour which
is adaptive to the autumnal colours of the foliage of their food-trees
would not assimilate to that of the newly-opened leaves in the spring.
I have already quoted (Proc. Zoo. Soc. 1873, p. 155) as instances
of what may be called “seasonal adaptation,” the larvæ of _Geometra
Papilionaria_, _Acidalia Degenararia_, and _Gnophos Obscurata_, and
many more could be named. These species undergo a change of colour
before or after hibernation, the change being always adaptive to the
environment.
It has long been known that caterpillars which feed on flowers or on
plants of variously-coloured foliage, in some cases partake of the
colour of their food. See, for instance, Dr. L. Möller’s memoir, “Die
Abhängigkeit der Inseckten von ihrer Umgebung,” 1867, and B. D. Walsh
“On Phytophagic Varieties and Phytophagic Species,” Proc. Ent. Soc.
Philadelph., vol. iii., p. 403. In 1865 Mr. R. McLachlan published a
paper entitled “Observations on some remarkable varieties of _Sterrha
Sacraria_, Linn., with general notes on variation in Lepidoptera”
(Trans. Ent. Soc. 1865, p. 453), in which he gave many illustrations
of this phenomenon. The larva of _Heliothis Peltiger_, according to
Mr. Reading’s description (Newman’s “British Moths,” p. 438), is
another case in point. In 1874 a number of instances were published
by Mr. Thomas G. Gentry in a paper entitled “Remarkable Variations in
Coloration, Ornamentation, &c., of certain Crepuscular and Nocturnal
Lepidopterous Larvæ” (“Canadian Entomologist,” vol. vi., p. 85. See
also W. H. Edwards’ description of the summer and autumnal larvæ of
_Lycæna Pseudargiolus_; _Ibid._, vol. x., pp. 12, 13).
The caterpillars of the _Sphingidæ_ appear also in some cases to vary
in a manner very suggestive of phytophagic influences. The observations
upon _S. Ocellatus_ recorded in the previous note (p. 241) may perhaps
be interpreted in this sense. In order to get experimental evidence
upon this subject, I may add that Mr. E. Boscher was good enough at
my request to repeat his observations, and conduct some breeding
experiments during the present year (1880). In the same locality as
that previously mentioned, seven larvæ were found feeding on _Salix
viminalis_, all of which were the bright green spotted variety; and
in the same osier-bed six more were found on another species of
_Salix_, two of these being the bluish-green variety, and the other
four the bright green form. Unless we have here a local race, these
observations, in connection with those of last year, tend to show
that the light green form is associated with _Salix viminalis_. When
found in the natural state feeding on apple, the caterpillar of this
species is generally, perhaps invariably, the bluish-green form. In
order to try the effect of breeding the larvæ _ab ovo_ on distinct
food-plants, a large number of eggs laid by a female _Ocellatus_ in
July were divided into three batches, one being supplied with _Salix
triandra_, another with _S. viminalis_, and the third lot with apple.
The experiment unfortunately failed in great part, owing to most of the
larvæ dying off, three from the third lot only surviving; but these
were all of the bluish-green form, which colour was shown by all the
caterpillars of this batch from their earliest stage. The observation
is thus so far successful, as it goes to support the view that the
variety mentioned is associated with apple (and _S. triandra?_) My
friend Mr. W. J. Argent informs me that he had a number of specimens
of _Sphinx Ligustri_ in his possession this autumn, some of which had
been found on lilac and others on laurestinus, and he states that all
those on the latter plant had the ground-colour distinctly darker than
in those feeding on lilac. I learn also from Mr. W. Davis, of Dartford,
that he found a number of these larvæ this year feeding on ash, and
that they were all differently coloured to those found on lilac or
privet, being of a more greyish-green. Another case of colour-variation
in larvæ is that _Emmelesia Unifasciata_, specimens of which I have
recently had an opportunity of examining, through the courtesy of Mr.
W. Davis. This species feeds on the seeds of a species of _Bartsia_
when the capsules are in various stages of growth, and (omitting
details of marking) those caterpillars found on the green capsules
were green, whilst those on the brown capsules were of a corresponding
colour.
On the whole I am inclined to believe that sufficient importance
has not hitherto been given to phytophagic variability as a
factor in determining larval coloration, and a large field for
experimental investigation here lies open for future work. The
obscure chemico-physiological processes which may perhaps be shown
by such researches to lead to phytophagic variation, cannot, I am
persuaded, produce any great divergence of character if unaided;
but when such causes of variability play into the hands of natural
selection variations of direct _protective advantage_ to the species,
we can easily see that this all-important agency would seize upon and
perpetuate such a power of adaptability to a variable environment. (See
Proc. Zoo. Soc. 1873, p. 158, and “Nature,” vol. xiv., pp. 329 and
330.) R.M.]
[141] [In 1879 Mr. George Francis, of Adelaide, forwarded from the
latter place a number of moths (a species of Anapæa) together with
their larvæ (in alcohol) and cocoons (Proc. Ent. Soc. 1879, p. xvi),
and in an accompanying note he stated that the male larva when living
is of “a bright emerald green, with red and pink markings on the back,
and yellow, black, and white streaks on the sides.” The male larva
is described as being smaller than the female, and as possessing
all the brilliant colours, the latter “having no red markings, but
only white, yellow, and green, with a little black.” I was at first
disposed to think that we might be dealing here with two distinct
species having differently marked larvæ; but Mr. Francis this present
year (1880) forwarded a large number of the living cocoons of this
species, which I separated according to size, and, on the emergence
of the moths (August), I found that all those from the small cocoons
were males, and those from the larger cocoons females. There can be no
doubt, therefore, that we have but one species in this case, the larva
of which presents the remarkable phenomenon of sexual difference of
coloration. As an analogous fact I may here mention the well-known case
of _Orgyia Antiqua_, the larva of which differs in the colour of the
tufts of hair according to sex. R.M.]
[142] [I have already given reasons for suspecting that the colour of
green caterpillars may be due to the presence of chlorophyll (or some
derivative thereof) in their tissues (see Proc. Zoo. Soc. 1873, p.
159). This substance appears to be one of great chemical stability,
and, according to Chautard, who has detected it in an unaltered
state in the tissues of certain leaf-feeding insects by means of its
absorption spectrum (“Comp. Rend.” Jan. 13th, 1873), it resists the
animal digestive processes (Ann. Ch. Phys. [5], iii., 1-56). If this
view should be established by future observations, we must regard the
green colour of caterpillars as having been produced, when protective,
from phytophagic variability by the action of natural selection; and
the absence of colour in internal feeders, above referred to, is only
secondarily due to the exclusion of light, and depends primarily on
the absence of chlorophyll in their food. In connection with this
I may adduce the fact, that some few species of _Nepticula_ (_N.
Oxyacanthella_, _N. Viscerella_, &c.) are green, although they live in
leaf-galleries where this colour can hardly be of use as a protection;
but their food (hawthorn and elm) contains chlorophyll. See also note
130, p. 293. Further investigations in this direction are much needed.
R.M.]
[143] [The same applies to _Pseudoterpna Cytisaria_, also feeding on
broom at the same time of the year. The most striking cases of adaptive
resemblance brought about by longitudinal stripes are to be found among
fir and pine feeders, species belonging to the most diverse families
(_Hyloicus Pinastri_, _Trachea Piniperda_, _Fidonia Piniaria_, &c.,
&c.) all being most admirably concealed among the needle-shaped leaves.
R.M.]
[144] The geographical distribution of the dark form indicates that
in the case of this species also, the form referred to is replacing
the yellow (green) variety. Whilst in the middle of Europe (Germany,
France, Hungary) the dark form is extremely rare, in the south of
Spain this variety, as I learn from Dr. Noll, is almost as common as
the yellow one. I hear also from Dr. Staudinger that in South Africa
(Port Natal) the dark form is somewhat the commoner, although the
golden-yellow and, more rarely, the green varieties, occur there. I
have seen a caterpillar and several moths from Port Natal, and these
all agree exactly with ours. The displacement of the green (yellow)
form by the dark soil-adapted variety, appears therefore to proceed
more rapidly in a warm than in a temperate climate. [Eng. ed. Dr.
Noll writes to me from Frankfort that the caterpillar of _Acherontia
Atropos_ in the south of Spain does not, as with us, conceal itself by
day in the earth, but on the stems underneath the leaves. “At Cadiz, on
the hot, sandy shore, _Solanum violaceum_ grows to a height of three
feet, and on a single plant I often found more than a dozen _Atropos_
larvæ resting with the head retracted. It can easily be understood
why the lateral stripes are blue when one has seen the south European
_Solaneæ_, on which this larva is at home. _Solanum violaceum_ is
scarcely green: violet tints alternate with brown, green, and yellow
over the whole plant, and between these appear the yellow-anthered
flowers, and golden-yellow berries of the size of a greengage. Thus
it happens that the numerous thorns, an inch long, between which the
caterpillar rests on the stem, pass from violet into shades of blue,
red, green, and yellow.”]
[145] [For Mr. J. P. Mansel Weale’s remarks on the habits of certain
ocellated S. African Sphinx-larvæ see note 129, p. 290. R.M.]
[146] [Some experiments with the caterpillar of _C. Elpenor_,
confirming these results, have been made by Lady Verney. See “Good
Words,” Dec. 1877, p. 838. R.M.]
[147] [The eye-spots on _Ch. Nerii_ have thus been supposed by some
observers to be imitations of the flowers of the periwinkle, one of
its food-plants. See, for instance, Sir John Lubbock’s “Scientific
Lectures,” p. 51. R.M.]
[148] “On Insects and Insectivorous Birds,” Trans. Ent. Soc. 1869, p.
21.
[149] _Ibid._, p. 27.
[150] [Messrs. Weir and Butler inform me that they have not
experimented with Sphinx-larvæ. R.M.]
[151] [It appears that the nauseous character of these last butterflies
is to a certain extent retained after death, as I found that in an
old collection which had been destroyed by mites, the least mutilated
specimens were species of _Danais_ and _Euplæa_, genera which are known
to be distasteful when living, and to serve as models for mimicry. See
Proc. Ent. Soc. 1877, p. xii. R.M.]
[152] [This bears out the view expressed in a previous note 129, p.
290, that the grotesque attitude and caudal tentacles are more for
protection against ichneumons than against larger foes. R.M.]
[153] These experiments, as already mentioned above, were not made with
the common German lizard (_Lacerta Stirpium_), but with the large South
European _Lacerta Viridis_.
[154] Thus, Boisduval states of this caterpillar, which in Provence
lives on _Euphorbia esula_ and allied species:--“Its resemblance
to a serpent, and its brilliant colour, permit of its being easily
discovered.” This was written in 1843, long before natural selection
was thought of.
[155] Or some other extinct analogously-marked species.
[156] [See Darwin’s remarks on the struggle for life being most severe
between individuals and varieties of the same species “Origin of
Species,” 6th ed. p. 59. R.M.]
[157] [Compare this with Darwin’s remarks on “analogous variations,”
“Origin of Species,” 6th ed., p. 125. R.M.]
[158] “Zoologische Studien auf Capri. II. Lacerta muralis cærula,
ein Beitrag zur Darwin’schen Lehre.” Leipzig, 1874. [The subject of
colour-variation in lizards has been much discussed in “Nature” since
the publication of the above mentioned essay; see vol. xix., pp. 4, 53,
97, and 122, and vol. xx., pp. 290 and 480. R M.]
[159] “Über die Berechtigung der Darwin’schen Theorie.” Leipzig,
1868. See also the previous essay “On the Seasonal Dimorphism of
Butterflies,” pp. 112-116.
[160] [Mr. A. G. Butler has recently advanced the view that this family
is not allied to the _Sphingidæ_, but is related on the one side to the
_Pyrales_, and on the other to the _Gelechiidæ_. See his paper “On the
Natural Affinities of the Lepidopterous Family _Ægeriidæ_,” Trans. Ent.
Soc. 1878, p. 121. R.M.]
[161] I am indebted to my esteemed colleague, Prof. Gestäcker, for the
knowledge of this specimen.
[162] Cat. Lep. East India Co., Pl. VIII.
[163] Such a residue is distinctly visible in _S. Ocellatus_: see Fig.
70, Pl. VII.
[164] [The question here also suggests itself as to why the _dorsal_
line should not have been the primary longitudinal stripe, seeing
that such a marking is almost naturally produced in many caterpillars
by the food in the alimentary canal; or, in other words, why has not
natural selection taken advantage of such an obvious means of producing
a stripe in cases where it would have been advantageous? In answer
to this I may state, that in large numbers of species the dorsal
line has thus become utilized; but in the case of large caterpillars
resting among foliage, it can be easily seen that light lateral (_i.e._
subdorsal) stripes, are more effective in breaking the homogeneity
of the body than a dorsal line only slightly darker than the general
ground-colour. Lateral lines are in fact visible from _two directions
of space_. If a caterpillar thus marked be placed on a twig, these
lines are visible when we look at the creature’s back or at either
side. That the subdorsal are therefore the primary lines, as shown by
Dr. Weismann’s observations of the ontogeny of many of the _Sphingidæ_,
is quite in harmony with the view of their having been produced by
natural selection. R.M.]
[165] “Die Darwin’sche Theorie. Elf Vorlesungen über die Entstehung der
Thiere und Pflanzen durch Naturzüchtung.” 2nd ed., Leipzig, 1875, p.
195.
[166] [In the following species, already mentioned in previous
notes, the oblique stripes are bounded at their upper extremities by
a conspicuous subdorsal line:--_Acosmeryx Anceus_, Cram.; _Sphinx
Cingulata_, Fabr.; _Pachylia Ficus_, Linn.; _P. Syces_, Hübn. In
_Pseudosphinx Cyrtolophia_, Butl., the oblique white stripes,
beautifully shaded with pink, run into the white pink-bordered dorsal
line, so that when seen from above the markings present the appearance
of the midrib and lateral veins of a leaf, and are probably specially
adapted for this purpose. R.M.]
[167] [The dorsal line as well as the oblique stripes is present in
the caterpillar of _Smerinthus Tartarinovii_, Ménét.; and in _Ambulyx
Gannascus_, Stoll., the oblique stripes are bounded above by a
subdorsal line, as in the species named in the preceding note. R.M.]
[168] Cat. Lep. East India Co., Pl. XI.
[169] [Compare this with Darwin’s “Origin of Species” (1st. ed. p.
440), where it is stated that when an animal, during any part of its
embryonic career, is active, and has to provide for itself, “the
period of activity may come on earlier or later in life; but whenever
it comes on, the adaptation of the larva to its conditions of life is
just as perfect and beautiful as in the adult animal. From such special
adaptations the similarity of the larvæ or active embryos of allied
animals is sometimes much obscured.” R.M.]
[170] [For Fritz Müller’s application of this principle to the case of
certain groups of Brazilian butterflies see Appendix II. to this Part.
R.M.]
[171] [The slight variability in the colour of this pupa, opens up
the interesting question of the photographic sensitiveness of this
and other species, which is stated to cause them to assimilate in
colour to the surface on which the larva undergoes its final ecdysis.
Some experiments upon this subject have been recorded by Mr. T. W.
Wood, Proc. Ent. Soc. 1867, p. xcix, but the field is still almost
unexplored. R.M.]
[172] “Über den Einfluss der Isolirung auf die Artbildung.” Leipzig,
1872, p. 20.
[173] In some instances _Deilephila Lineata_ has also been seen by day
hovering over flowers.
[174] It is true that I only reared one brood, but from this fifty
specimens were obtained. It would be interesting to know whether this
variety of the caterpillar is distributed over the whole of Southern
Europe.
[175] In this sense Lubbock says:--“It is evident that creatures which,
like the majority of insects, live during the successive periods
of their existence in very different circumstances, may undergo
considerable changes in their larval organization in consequence of
forces acting on them while in that condition; not, indeed, without
affecting, _but certainly without affecting to any corresponding
extent_, their ultimate form.”--“Origin and Metamorphoses of Insects,”
London, 1874, p. 39.
[176] “Grundzüge der Zoologie,” 1875.
[177] [Lepidopterists are of course aware that even these distinctions
are not absolute, as no single character can be named which does not
also appear in certain moths. The definition in this case, as in that
of most other groups of animals and plants, is only a general one.
See, for instance, Westwood’s “Introduction to the Classification of
Insects,” vol. ii. pp. 330-332. Also some remarks by C. V. Riley in his
“Eighth Annual Report” on the insects of Missouri, 1876, p. 170. With
reference to the antennæ as a distinguishing character, see Mr. A. G.
Butler’s article in “Science for All,” 1880, part xxvii. p. 65. R.M.]
[178] The genus of _Morphinæ, Discophora_, possesses hairs very similar
to those of the genus _Cnethocampa_ belonging to the _Bombycidæ_.
[179] [The larvæ of genera 14, _Phyciodes_, and 35, _Crenis_, are
likewise spiny. See Edwards’ “Butt. of N. Amer.” vol. ii. for figures
of the caterpillar of _Phyc. Tharos_: for notes on the larvæ of
_Crenis Natalensis_ and _C. Boisduvali_ see a paper by W. D. Gooch,
“Entomologist,” vol. xiv. p. 36. The larvæ of genus 55, _Ageronia_, are
also spiny. (See Burmeister’s figure of _A. Arethusa_, “Lép. Rép. Arg.”
Pl. V. Fig. 4). The larvæ of genus 98, _Aganisthos_, also appear to be
somewhat spiny (see Burmeister’s figure of _A. Orion_, _loc. cit._ Pl.
V. Fig. 6), and this raises the question as to whether the genus is
correctly located in its present position. The larvæ of the following
genera figured in Moore’s “Lepidoptera of Ceylon,” parts i. and ii.,
are all spiny:--6, _Cirrochroa_ (Pl. XXXII.); 7, _Cynthia_ (Pl. XXVI.);
27, _Kallima_ (Pl. XIX.); and 74, _Parthenos_ (Pl. XXIV.). Many species
of caterpillars which are spiny when adult appear to be spineless,
or only slightly hairy when young. See Edwards’ figures of _Melitæa
Phaeton_, _Argynnis Diana_, and _Phyc. Tharos_ (_loc. cit._) and his
description of the larva of _Arg. Cybele_, “Canad. Entom.” vol. xii. p.
141. The spiny covering thus appears to be a character acquired at a
comparatively recent period in the phyletic development. R.M.]
[180] [The larvæ of the 110th genus, _Paphia_, Fabr. (_Anæa_, Hübn.)
are also smoothed-skinned. See Edwards’ figure (_loc. cit._ vol. i. Pl.
XLVI.) of _P. Glycerium_. Also C. V. Riley’s “Second Annual Report” on
the insects of Missouri, 1870, p. 125. Burmeister figures the larva of
a species of _Prepona_ (genus 99) which is smooth (_P. Demophon_, _loc.
cit._ Pl. V. Fig. 1). The horns on the head of _Apatura_, &c., may
possibly be a survival from a former spiny condition. R.M.]
[181] “Synopsis of the described Lepidoptera of North America.”
Washington, 1862.
[182] “Catalog der Lepidopteren des Europäischen Faunengebietes.”
Dresden, 1871.
[183] This group of moths (“Schwärmer”) is regarded as of very
different extents by systematists; when I here comprise under it only
the _Sphingidæ_ proper and the _Sesiidæ_, I by no means ignore the
grounds which favour a greater extension of the group; the latter is
not rigidly limited. [The affinities of the _Sesiidæ_ (_Ægeriidæ_) are
by no means clearly made out: it appears probable that they are not
related to the _Sphingidæ_. See note 160, p. 370. R.M.]
[184] [For Mr. A. G. Butler’s observations on the genus _Acronycta_,
see “Trans. Ent. Soc.” 1879, p. 313; and note 68, p. 169, of the present
volume. R.M.]
[185] [The following characters are given in Stainton’s “Manual of
British Butterflies and Moths,” vol. i. p. 114:--“Larva of very
variable form: at one extreme we find the singular _Cerura_ larvæ,
with only fourteen legs, and two long projecting tails from the last
segment; at the other extreme we have larvæ with sixteen legs and no
peculiarity of form, such as _Chaonia_ and _Bucephala_; most have,
however, the peculiarity of holding the hind segment of the body erect
when in repose; generally quite naked, though downy in _Bucephala_ and
rather hairy in _Curtulu_; very frequently there are projections on the
back of the twelfth segment.” R.M.]
[186] Encyl. Meth. ix. p. 310.
[187] [The genus _Vanessa_ (in the wide sense) appears to be in a
remarkable condition of what may be called phyletic preservation.
Thus, the group of species allied to _V. C.-album_ passes by almost
insensible steps into the group of butterflies typified by our
“Tortoiseshells.” The following is a list of some of the intermediate
species in their transitional order:--_I.-album_, _V.-album_, _Faunus_,
_Comma_, _California_, _Dryas_, _Polychloros_, _Xanthomelas_,
_Cashmirensis_, _Urticæ_, _Milberti_, &c. Similarly, our _Atalanta_
and _Cardui_ are connected by a number of intermediate forms, showing
a complete transition from the one to the other. The following is the
order of the species so far as I am acquainted with them:--_Atalanta_,
_Dejeanii_, _Callirhoë_, _Tammeamea_, _Myrinna_, _Huntera_,
_Terpsichore_, _Carye_, _Kershawii_, and _Cardui_. R.M.]
[188] “Prodromus Systematis Lepidopterorum.” Regensburg, 1864.
[189] [The larva of _Acherontia Morta_, figured by Butler (see note 121,
p. 262), possesses the characteristically recurved horn; that of _Ach.
Medusa_ figured by the same author, does not appear to possess this
character in any marked degree. R.M.]
[190] [See note 97, p. 233. R.M.]
[191] _Loc. cit._ Pl. XXV. [This species is referred by Butler to the
genus _Paonias_, Hübn. R.M.]
[192] Abbot and Smith, Pl. XXIX. [Placed by Butler in the genus
_Cressonia_, Grote and Robinson. Abbot and Smith state that this
larva is sometimes green. According to Mr. Herman Strecker (Lepidop.
Rhopal. and Hetero, Reading, Pa. 1874, p. 54) it feeds upon black
walnut (_Juglans Nigra_), hickory (_Carya Alba_), and ironwood
(_Ostrya Virginica_). Of the North American species of _Smerinthus_,
the following, in addition to _Excæcatus_, closely resemble our
_Ocellatus_:--_S. (Calasymbolus) Geminatus_, Say; _(C.) Cerisii_,
Kirby; and _Ophthalmicus_, Boisd. In addition to _S. (Cressonia)
Juglandis_, _S. (Triptogon) Modesta_ much resembles our _Populi_. The
larva of _Geminatus_, according to Strecker, is “pale green, lightest
above, with yellow lateral granulated stripes; caudal horn violet;
stigmata red. It feeds on the willow.” R.M.]
[193] Cat. Brit. Mus.
[194] [This lengthening of the true legs is mimetic according to
Hermann Müller, and causes the anterior portion of the caterpillar to
resemble a spider. See note 129, p. 290. R.M.]
[195] [Certain butterflies appear to be crepuscular, if not nocturnal
in their habits. Thus in his “Notes on the Lepidoptera of Natal,” Mr.
W. D. Gooch states that he never saw _Melanitis_, _Leda_, or _Gnophodes
Parmeno_ on the wing by day, but generally during the hour after
sunset. He adds:--“My sugar always attracted them freely, even up to
10 or 11 p.m.” Many species of _Hesperidæ_ are also stated to be of
crepuscular habits by this same observer. See “Entomologist,” vol xvi.
pp. 38 and 40. R.M.]
[196] I only make this assumption for the sake of simplicity, and not
because I am convinced that the existing _Rhopalocera_ are actually the
oldest Lepidopterous group.
[197] Zeitschrift für wissenschaftl. Zoologie, vol. xx. p. 519.
[198] [See for instance Lubbock’s “Origin and Metamorphoses of
Insects,” chap. iii.; and F. M. Balfour’s “Comparative Embryology,”
vol. i., 1880, pp. 327--356. This last work contains an admirable
_résumé_ of our knowledge of the embryonic development of insects up to
the date of publication. R.M.]
[199] Are not the 4th, 11th, and 12th segments destitute of the
rudiments of legs as in the larvæ of all existing saw-flies? I might
almost infer this from Bütschli’s figures (see for instance Pl. XXV.,
Fig. 17A).
[200] [The grub-formed Hymenopterous larvæ, like the larvæ of all
other holometabolous insects, thus represent an acquired degenerative
stage in the development, _i.e._ an adaptation to the conditions of
life at that stage. Bearing in mind the above-quoted observations of
Bütschli and the caterpillar-like form of the Terebrantiate group of
Hymenopterous larvæ, the following remarks of Balfour’s (_loc. cit._ p.
353), appear highly suggestive:--“While in a general way it is clear
that the larval forms of insects cannot be expected to throw much light
on the nature of insect ancestors, it does nevertheless appear to me
probable that such forms as the caterpillars of the Lepidoptera are not
without a meaning in this respect. It is easy to conceive that even a
secondary larval form may have been produced by the prolongation of one
of the embryonic stages; and the general similarity of a caterpillar to
_Peripatus_, and the retention by it of post-thoracic appendages, are
facts which appear to favour this view of the origin of the caterpillar
form.” See also Sir John Lubbock, _loc. cit._, pp. 93 and 95. R.M.]
[201] [In the most recent works dealing with this order six
groups, based on the character of the imagines are recognized,
viz.:--_Tubulifera_, _Terebrantia_, _Pupivora_, _Heterogyna Fossores_,
and _Mellifera_. (See, for instance, F. P. Pascoe’s “Zoological
Classification,” 2nd ed. p. 147.) Of these groups the larvæ of the
_Terebrantia_ as thus restricted are all of the caterpillar type
(_Tenthredinidæ_ and _Siricidæ_), whilst those of the other groups are
maggot-shaped. For a description of the development of the remarkable
aberrant larva of _Platygaster_, see Ganin in Zeit. f. wissenschaftl.
Zool., vol. xix. 1869. R.M.]
[202] [For recent investigations on the structure of the thorax in
Diptera, see a paper by Mr. A. Hammond, in Journ. Linn. Soc., Zoology,
vol xv. p. 9. R.M.]
[203] I am familiar with the fact that the two sub-orders of true
Diptera, the short-horned (_Brachycera_), and the long-horned
(_Nemocera_), are not sharply limited; and I am likewise well
acquainted with the circumstance that there are forms which connect the
two larval types. The connecting forms of the imagines do not, however,
always coincide with the intermediate larval forms, so that there
here arises a second and very striking incongruence of morphological
relationship which depends only upon the circumstance that the one
stage has diverged in form more widely than the other through a greater
divergence in the conditions of life. The difficulty is in these cases
aggravated because an apparent is added to the true form-relationship
through convergence, so that without going into exact details the form
and genealogical relationships of the Diptera cannot be distinguished.
It would be of great interest for other reasons to make this
investigation, and I hope to be able to find leisure for this purpose
at some future period.
[204] “Entwicklung der Dipteren.” Leipzig, 1864.
[205] Lubbock concludes from the presence of thoracic legs in the
embryonic larva of bees that these have been derived from a larva of
the _Campodea_ type, but he overlooks the fact that the rudiments of
the abdominal legs are also present; _loc. cit._, p. 28.
[206] “Für Darwin,” Leipzig, 1864, p. 8.
[207] Mem. Peabody Acad. of Science, vol. i. No. 3.
[208] Verhandl. Wien. Zoolog. Botan. Gesellsch. 1869, p. 310.
[209] Über Ontogenie und Phylogenie der Insekten. Eine akademische
Preisschrift. Jen. Zeitschrift. Bd. x. Neue Folge, iii. Heft 2. 1876.
[Some remarks by F. M. Balfour on the origin of certain larval forms
have already been quoted in a previous note (p. 485). This author
further states:--“The fact that in a majority of instances it is
possible to trace an intimate connection between the surroundings
of a larva and its organization proves in the clearest way _that
the characters of the majority of existing larval forms of insects
have owed their origin to secondary adaptations_. A few instances
will illustrate this point:--In the simplest types of metamorphosis,
_e.g._ those of the Orthoptera genuina, the larva has precisely the
same habits as the adult. We find that a caterpillar form is assumed
by phytophagous larvæ amongst the Lepidoptera, Hymenoptera, and
Coleoptera. Where the larva has not to go in search of its nutriment
the grub-like apodous form is assumed. The existence of such an apodous
larva is especially striking in the Hymenoptera, in that rudiments
of thoracic and abdominal appendages are present in the embryo and
disappear again in the larva.... It follows from the above that the
development of such forms as the Orthoptera genuina is more primitive
than that of the holometabolous forms, &c.” Comparative Embryology,
vol. 1, p. 352. R.M.]
[210] [The _Aphaniptera_ are now recognized in this country as
a sub-order of Diptera. See, for instance, Huxley’s “Anatomy
of Invertebrated Animals,” p. 425, and Pascoe’s “Zoological
Classification,” 2nd ed. p. 122. R.M.]
[211] [This illustration of course only applies to the old arrangement
of the Hymenoptera into _Terebrantia_ and _Aculeata_. See also note 201,
p. 488. R.M.]
[212] [Eng. ed. This law is perhaps a little too restricted, inasmuch
as it is theoretically conceivable that the organism may be able
to adapt itself to similar conditions of life in different ways;
differences of form could thus depend sometimes upon differences of
adaptation and not upon differences in the conditions of life, or, as
I have formerly expressed it, it is not necessary to allow always only
_one_ best mode of adaptation.]
[213] [It must be understood that the word rendered here and elsewhere
throughout this work as “transformation” is not to be taken in the
narrow sense of metamorphosis, but as having the much broader meaning
of a change of any kind incurred by an organism. Metamorphosis is in
fact but one phase of transformation. R.M.]
[214] By the Editor.
[215] Mr. C. V. Riley in his excellent “Annual Reports” already
quoted in previous notes, states that the larvæ of _Agrotis Inermis_,
_Leucania Unipuncta_ (Army-worm), and _L. Albilinea_ are all loopers
when newly hatched. (See First Report, p. 73; Eighth Report, p. 184;
and Ninth Report, p. 53.)
[216] The following species not referred to in the previous part of
this work are figured by Semper (Beit. zur Entwicklungsgeschichte
einiger ostasiat. Schmet.; Verhandl. d. k.k. zoo. bot. Gesell. in Wien,
1867):--_Panacra Scapularis_, Walk.; _Chærocampa Clotho_, Drury; and
_Diludia (Macrosila) Discistriga_, Walk. The following are figured by
Boisduval and Guenée. (Spéc. Gén. 1874):--_Smerinthus Ophthalmicus_,
Boisd.; _Sphinx Jasminearum_, Boisd.; _S. (Hyloicus) Plebeia_, Fabr.;
_S. (Hyloicus) Cupressi_, Boisd.; _S. (Pseudosphinx) Catalpæ_, Boisd.;
_Philampelus Jussiuæ_, Hübn. (= _Sphinx Vitis_, Linn.?); and _Ceratomia
Amyntor_, Hübn. As the works of Abbot and Smith, and Horsfield and
Moore have been exhausted by Dr. Weismann, it is quite unnecessary
to extend this note by giving a list of the species figured by these
authors.
[217] The same inference has already been drawn with respect to
_Pterogon (Proserpinus) Œnotheræ_, see pp. 257, 258.
[218] This would of course be the _fourth_ segment if the head be
considered the first, as on the Continent.
[219] “Second Annual Report,” 1870, p. 78.
[220] “Entomologist,” vol. xiv. p. 7.
[221] With reference to the habits of _C. Capensis_ (p. 531), I have
since been informed by Mr. Trimen that this species does not conceal
itself by day, so that the dimorphism may be regarded as a character
retained from an earlier period and adapted to the present life
conditions.
[222] “Kosmos,” Dec. 1877, p. 218. The paper is here introduced chiefly
with a view to illustrate an important case of incongruence among
Lepidopterous pupæ.
[223] [Maracujá, the local name for the Passiflora. R.M.]
[224] See p. 448.
[225] Verhandl. Schweiz. Naturforsch. Gesellschaft. Einsiedeln, 1868.
[226] [Eng. ed. In 1878 Señor José M. Velasco published a paper
entitled “Description, metamorfosis. y costumbres de una especie nueva
del genero _Siredon_.” Memor. Sociedad Mexicana de Historia Natural,
December 26th. See Addendum to this essay.]
[227] Dana and Silliman’s Amer. Journ., 3rd series, i. p. 89. Annals
Nat. Hist. vii. p. 246.
[228] Proc. Zoo. Soc. 1870, p. 160.
[229] Compt. Rend., vol. lx. p. 765 (1865).
[230] Nouvelles Archives du Muséum d’Histoire Nat. Paris, 1866, vol.
ii. p. 268.
[231] Proc. Boston Soc., vol. xii. p. 97; Silliman’s Amer. Journ., vol.
xlvi. p. 364; reference given in “Troschel’s Jahresbericht” for 1868,
p. 37.
[232] Proc. Boston Soc., vol. xii. p. 97; Silliman’s Amer. Journ., vol.
xlvi. p. 364. I have not been able to get a copy of this paper, and
quote from a reference in “Troschel’s Jahresbericht.” See preceding
note.
[233] Dana and Silliman’s Amer. Journ. See note 3.
[234] Proc. Acad. Philadelph. xix. 1867, pp. 166-209.
[235] Mém. Acad. Petersb. vol. xvi.
[236] [Eng. ed. Seidlitz is an exception, since in his work on
Parthenogenesis (Leipzig, 1872, p. 13) he states that “In the Axolotl,
Pædogenesis, which is not in this case ... monogamous, but sexual, and
indeed gynækogenetic, has already become so far constant that it has
perhaps entirely superseded the orthogenetic reproduction.”]
[237] Über den Einfluss der Isolirung auf die Artbildung. Leipzig,
1872, p. 33.
[238] Duméril represents the teeth of the _vomer_ as separated from
those of the _os palatinum_ by a gap. This is probably accidental,
since Gegenbaur (Friedrich u. Gegenbaur, the skull of Axolotl,
Würzburg, 1849) figures the rows of teeth as passing over from the one
bone to the other without interruption. This was the case with the
Axolotls which I have been able to examine on this point; but this
small discrepancy is, however, quite immaterial to the question here
under consideration.
[239] See O. Hertwig “Über das Zahnsystem der Amphibien und seine
Bedeutung für die Genese des Skelets der Mundhöhle.” Archiv. für
microsc. Anat., vol. xi. Supplement, 1874.
[240] [Eng. ed. These Amblystomas have since died and have been
minutely described by Dr. Wiedersheim. See his memoir, “Zur Anatomie
des _Amblystoma Weismanni_,” in Zeit. für wiss. Zool., vol. xxxii. p.
216.]
[241] See Strauch, _loc. cit._ p. 10.
[242] See Part I. of this volume.
[243] [This is the principle of “Degeneration” recognized by Darwin
(see “Origin of Species,” 6th ed. p. 389, and “Descent of Man,” vol.
i. p. 206), and given fuller expression to by Dr. Anton Dohrn (see
his work entitled “Der Ursprung der Wirbelthiere und das Princip des
Functionswechsels.” Leipzig, 1875). A large number of cases have been
brought together by Prof. E. R. Lankester, in his recent interesting
work on “Degeneration, a Chapter in Darwinism.” Nature series, 1880.
R.M.]
[244] “Sulla Larva del _Triton Alpestris_.” Archivio per la Zoologia.
Genova e Torino, 1861, vol. i. pp. 206-211.
[245] See also Lubbock “On the Origin and Metamorphoses of Insects,”
London, 1874.
[246] See the first essay “On the Seasonal Dimorphism of Butterflies,”
p. 82.
[247] [Eng. ed. It has frequently been objected to me that the existing
Axolotl is not a form resulting from atavism, but a case of “arrested
growth.” The expression “atavism” is certainly to be here taken in
a somewhat different sense than, for example, in the case of the
reversion of the existing Axolotl to the Amblystoma form. Further on, I
have myself insisted that in the first case the phyletic stage in which
the reversion occurred is still completely preserved in the ontogeny
of each individual, whilst the Amblystoma stage has become lost in the
ontogeny of the Axolotl. If, therefore, we apply the term “atavism”
only to such characters or stages (_i.e._ complexes of characters) as
are no longer preserved in the ontogeny, we cannot thus designate the
present arrest of the Axolotl at the perennibranchiate stage. Such a
restriction of the word, however, appears to me but little desirable,
since the process is identical in both cases, _i.e._ it depends upon
the same law of heredity, in accordance with which a condition formerly
occurring as a phyletic stage suddenly reappears through purely
internal processes. It is true that the reversion is not _complete_,
_i.e._ the present sexually mature Axolotl does not correspond in all
details with its perennibranchiate ancestors. Since Wiedersheim has
shown that the existing Axolotl possesses an intermaxillary gland, this
can be safely asserted. This gland occurs only in _land_ Amphibians,
and therefore originated with the Amblystoma form, afterwards becoming
transferred secondarily to the larval stage. Nevertheless, the present
Axolotl must resemble its perennibranchiate ancestors in most other
characters, and we should be the more entitled to speak of a reversion
to the perennibranchiate stage as we speak also of the reversion of
single characters. To this must be added that the Axolotl does not
correspond exactly with an Amblystoma larva, since Wiedersheim has
shown that the space for the intermaxillary gland is present, but that
the gland itself is confined to a few tubes which do not by any means
fill up this space. (“Das Kopfskelet der Urodelen.” Morph. Jahrbuch,
vol. iii. p. 149). By the expression “arrested growth” not much is
said, if at the same time the cause of the arrest is left unstated. But
what can be the cause why the whole organization remains stationary at
the perennibranchiate stage, the sexual organs only undergoing further
development? Surely only that law or force of heredity known by its
effects, but obscure with respect to its causes, through which old
phyletic stages sometimes suddenly reappear, or in other words, that
power through which reversion takes place. It must not be forgotten
that all these cases of “larval reproduction” in Amphibians appear
suddenly. The present sexually mature form of the Axolotl has not
arisen by the sexual maturity gradually receding in the ontogeny from
generation to generation, but by the occurrence of single individuals
which were sexually mature in the perennibranchiate stage, these having
the advantage over the _Amblystomæ_ in the struggle for existence under
changed climatic conditions.
By admitting a reversion, we perfectly well explain why arrest at the
perennibranchiate stage can be associated with complete development of
the sexual organs; the assumption of an “arrested growth” leaves this
combination of characters completely unexplained. Moreover, I am of
opinion that the expressions “arrested growth” or “reversion” are of
but little importance so long as the matter itself is clear.]
[248] See Haeckel’s “Anthropogenie,” p. 449.
[249] “Der Ursprung der Wirbelthiere und das Princip des
Functionswechsels,” Leipzig, 1875.
[250] Bull. Soc. Neuchâtel. vol. viii. p. 192. Reference given in
“Troschel’s Jahresbericht” for 1869.
[251] Sitzungsberichte d. math. phys. Klasse der Akad. d. Wiss. zu
München, 1875. Heft i.
[252] Compt. Rend. vol. lxviii. pp. 938 and 939.
[253] Archiv f. Naturgeschichte, 1867.
[254] Compt. Rend. vol. v. 1870, p. 70.
[255] Bull. Soc. Neuchâtel. vol. viii. p. 192. Reference given in
“Troschel’s Jahresbericht” for 1869.
[256] [Eng. ed. It was mentioned in the German edition of this work
that in the spring of 1876 a female Amblystoma of the Jardin des
Plantes in Paris had laid eggs (see Blanchard in the Compt. Rend. 1876,
No. 13, p. 716). Whether these eggs were fertile, or whether they
developed was not then made known. Thus much was however at the time
clear, that even if this had been the case, the reproduction of this
Amblystoma would have been only an _exceptional_ occurrence. At that
time there were in the Jardin des Plantes Amblystomas which had been
kept for more than ten years, and only on one occasion was there a
deposition of eggs, and this by only one specimen. That I was correct
in speaking of the “sterility” of these Amblystomas in spite of this
one exception, is proved by the latest communication from the Jardin
des Plantes. We learn from this (Compt. Rend. No. 14, July, 1879, p.
108) that in the years 1877 and 1878 none of the Amblystomas laid any
more eggs, although all means were exerted to bring about propagation.
In April, 1879, eggs were again laid by one female, and by a second in
May. These eggs certainly developed, as did those of 1876, and produced
tadpoles. These Amblystomas are therefore not absolutely, but indeed
relatively sterile. Whilst the Axolotl propagates regularly and freely
every year, this occurs with the Amblystoma but rarely and sparsely.
The degree of their sterility can only be approximately established
when we know the number of Amblystomas that have since been kept in the
Jardin des Plantes. Unfortunately nothing has been said with respect to
this.]
[257] Origin of Species, 6th ed. p. 252.
[258] In plants also reversion forms show sterility in different
degrees. Mr. Darwin has called my attention to the fact that the
peloric (symmetrical) flowers which occasionally appear as atavistic
forms in _Corydalis solida_ are partly sterile and partly fertile.
That in other causes of sterility, and above all by bastardizing, the
reproductive power is lost in the most varying degrees, has been known
since the celebrated observations of Kölreuter and Gärtner. [Eng.
ed. An Orchid (_Catasetum tridentatum_) has the sexes separate, and
the male flowers (_Myanthus barbatus_) differ considerably from the
female (_Monachanthus viridis_); besides these, there occurs a form
with bisexual flowers which must be considered as a reversion (_Cat.
tridentatum_) and _this is always sterile_. Darwin, “Fertilization of
Orchids,” 2nd ed. p. 199.]
[259] As we do not know the origin of the “Paris Axolotl” I must
restrict myself in the following remarks to _Siredon Mexicanus_ (Shaw).
[260] Mühlenpfordt, “Versuch einer getreuen Schilderung der Republik
Mejico,” Hanover, 1844, vol. ii. p. 252.
[261] [The specific gravity of sea water (Atlantic), according to the
determinations of Mr. Buchanan on board the “Challenger,” at 15.56°
C. varies from 1.0278 to 1.0240. That of the water of the Dead Sea is
1.17205.--Watts’ “Dict. of Chemistry,” vol. v., table, p. 1017. R.M.]
[262] _Loc. cit._ p. 252.
[263] “Über die specifische Verschiedenheit des gefleckten und des
schwarzen Erdsalamanders oder Molchs, und der höchst merkwürdigen, ganz
eigenthümlichen Fortpflanzungsweise des Letzteren.” Isis, Jahrg. 1833,
p. 527.
[264] The experiments referred to have not been made known; I am
indebted for them to a written communication kindly furnished by an
esteemed colleague.
[265] See Mühlenpfordt’s work already quoted, vol. i.
[266] In the province of botany such a case has already been made
known by Fritz Müller (Botan. Zeitung, 1869, p. 226; 1870, p. 149). I
may be here permitted to quote a passage from the letter in which Dr.
Müller calls attention to this interesting discovery. “As a proof of
the possibility that a reversion form can again become a persistent
character in a species or in the allied form of a particular district,
I may refer you to an _Epidendrum_ of the island of Santa Catharina.
In all Orchids (with the exception of _Cypripedium_) only one anther
is developed; in very rare cases well-formed anthers appear as
reversions among the aborted lateral anthers of the inner whorl. In the
_Epidendrum_ mentioned, these are however _always present_.”
[267] [This species is interesting as being ovoviviparous, the young
passing through the branchiate stage within the body of the mother.
Some experiments, which were partially successful, were made by
Fräulein v. Chauvin with a view to solve the question whether the
branchiate stage could be prolonged by taking the larvæ directly from
the mother before birth and keeping them in water. See “Zeit. für
wissen. Zoo.” vol. xxix., p. 324. R.M.]
[268] See Fatiot, “Les Reptiles et les Batraciens de la haute
Engadine.” Geneva, 1873.
[269] I can remember at Upper Engadine a peculiar kind of preserved
beef, prepared by simply drying in the air; also the mummification of
entire human bodies by drying in the open air, as is practised at Great
St. Bernard.
[270] “Faune des Vertébrés de la Suisse,” vol. iii. “Histoire Naturelle
des Reptiles et des Batraciens.” Geneva, 1873.
[271] See Wiedersheim, “Versuch einer gleichenden Anatomie der
Salamandrinen.” Würzburg, 1875.
[272] See Gené, “Memorie della Reale Acad. di Torino,” vol. i.
[273] _Rana esculenta_ never reaches Alpine regions, this species not
having been found higher than 1100 meters. (Fatiot, _loc. cit._, p.
318.)
[274] See also the excellent work upon Mexico by Mühlenpfordt already
quoted, vol. i., pp. 69-76.
[275] “Essai politique sur le Royaume de la Nouvelle Espagne,” 1805, p.
291.
[276] [The expression made use of by the author, viz. “Diluvialzeit,”
would perhaps be more in harmony with the views of English geologists
if rendered as the “pluvial period,” thereby indicating the period of
excessive rainfall which, according to Mr. Alfred Tylor, succeeded
to and was a consequence of the thawing of the great glaciers which
accumulated during the last glacial epoch. There is abundant evidence
to show that during the latter period glacial action extended in North
America at least as far south as Nicaragua. See Belt on “The Glacial
Period in North America,” Trans. Nova Scotian Inst. of Nat. Sci. 1866,
p. 93, and “The Naturalist in Nicaragua,” pp. 259-265. R.M.]
[277] [Eng. ed. A memoir by Samuel Clarke has since been published upon
the embryonic development of _Amblystoma punctatum_, Baird. Baltimore,
1879.]
[278] [Eng. ed. See this author’s work, “Das Kopfskelet der Urodelen.”
Leipzig, 1877, p. 149.]
[279] [See preceding note 52. R.M.]
[280] See note 226, p. 566.
[281] [Prof. Semper also remarks (“Animal Life,” note 47, p. 430) with
reference to the Axolotl of Lake Como in the Rocky Mountains, which he
states always becomes transformed into _Amblystoma Mavortium_, that
this metamorphosis “takes place in the water, and the Amblystomas, so
long as they are little, actually live exclusively in the water, as I
know by my own experience. A young Amblystoma which I kept alive for a
long time, never went out of the water of its own free will, while one
nearly twice as large lives entirely on land and only takes a bath now
and then. It always goes into the water when the temperature of the
air in the cellar, in which my aquaria stand, falls below that of the
water--down to about 6° or 8° C.” This statement appears to suggest
that the effect of temperature may be a factor in some way concerned
in these interesting cases of transformation, and would in any case
be well worthy of experimental investigation. Some further details
concerning the _Siredon Lichenoides_ of Lake Como have been recently
published by Mr. W. E. Carlin (Proc. U.S. National Museum, June, 1881).
The lake, which is shallow, is fed by a constant stream of fresh water,
but the water of the lake is intensely saline. The Siredon never enter
the fresh water stream, but congregate in large numbers in the alkaline
waters of the lake. “When about one hundred and fifty were placed
in fresh water they seemed to suffer no inconvenience, but it had a
remarkable effect in hastening their metamorphosis into the Amblystoma
form. Of an equal number kept in fresh water and in the lake water,
quite a change occurred with the former after twenty-four hours, while
the latter showed no change after several days of captivity. Those that
were kept well fed in jars usually began to show a slight change in
from two to three weeks, and all of them completed the change into the
Amblystoma inside of six weeks, while in some kept, but not specially
fed, there were but three changes in three months.” (Nature, Aug. 25th,
1881, p. 388.) R.M.]
[282] [Some experiments on the transformation of the Crustacean
_Artemia Salina_ into _A. Milhausenii_ by gradually increasing the
saltness of the water, and conversely, the transformation of _A.
Milhausenii_ into _A. Salina_ by diminishing the saltness of the water,
have been made by Schmankewitsch (Zeitschrift f. wiss. Zool. xxv.
Suppl. 103 and xxix. 429), but the changes which occur here are much
less considerable than in the case of the Axolotl. R.M.]
[283] “Reden und kleinere Aufsätze, Th. II.: Studien aus dem Gebiete
der Naturwissenschaften.” St. Petersburg, 1876, p. 81.
[284] This obviously does not imply that the naturalist should not
investigate Nature’s processes, and not only correlate these, but also
work them up into a universal conception; this is indeed both desirable
and necessary if natural knowledge is to be regarded in its true value.
The naturalist by this means becomes a philosopher, and the vitality
of the so-called “natural philosopher” has been inspired, not by the
necessity for investigation, but by philosophy proper.
[285] [The discovery here referred to is the synthesis of urea by
Wöhler in 1828 (Pogg. Ann. xii., 253; xv. 619), by the molecular
transformation of ammonium cyanate. Since that period large numbers
of organic syntheses have been effected by chemists, and many of the
compounds formerly supposed to be essential products of life have been
built up in the laboratory from their inorganic elements. The division
of chemistry into “organic” and “inorganic” is thus purely artificial,
and is merely retained as a matter of convenience, the former division
of the science being defined as the chemistry of the carbon compounds.
R.M.]
[286] “Wahreit und Irrthum im Darwinismus.” Berlin, 1875.
[287] [Eng. ed. I have been reproached by competent authorities for
having clothed my ideas upon the theory of selection in the form of
a reply to Von Hartmann. I willingly admit that this author cannot
be considered as the leader of existing philosophical views upon the
theory of descent in Germany; Frederick Albert Lange has certainly a
much greater claim to this position. Lange does not however combat
this theory; he accepts and develops it most beautifully and lucidly
on a sound philosophical basis in such a manner as has never been
done before from this point of view (“Geschichte des Materialismus,”
3rd. ed., 1877, vol. ii. pp. 253-277). On most points I can but agree
with Lange. Von Hartmann, however, whose objections appeared to me to
be supported by a wide scientific knowledge, afforded me a suitable
opportunity of developing my own ideas upon some essential points
in the theory of selection. In this sense only have I attempted to
interfere with this author, the refutation of his views, as such,
having been with me a secondary consideration.] [The chief exponent
of the doctrine of organic evolution in this country is Mr. Herbert
Spencer, in whose “Principles of Biology,” vol. i. chap. xii., will be
found a masterly treatment of the theory of descent from a “mechanical”
point of view. R.M.]
[288] [The above views on the nature of variability, which were also
broadly expressed in the first essay “On the Seasonal Dimorphism of
Butterflies” (pp. 114, 115), are fully confirmed by Herbert Spencer
(_loc. cit._ chaps. ix. and x.), and more recently by A. R. Wallace in
an article on “The Origin of Species and Genera” (_Nineteenth Century_,
vol. vii., 1880, p. 93). See also some remarks by Oscar Schmidt in his
“Doctrine of Descent and Darwinism,” Internat. Scien. Ser. 3rd. ed.
1876, p. 173. R.M.]
[289] [This law has been beautifully applied by Herbert Spencer in
order to explain why, with an unlimited supply of food, an organism
does not indefinitely increase in size. “Principles of Biology,” vol.
i. p. 121-126. R.M.]
[290] [Eng. ed. This idea, formerly expressed by me, occurs also
in Lange (“Geschichte des Materialismus,” ii. 265), and is there
exemplified in a very beautiful manner by illustrations from modern
chemistry. Lange compares what I have termed above the “physical
constitution” of the organism to the chemical constitution of one of
those organic acids which by substitution of single elements may become
transformed into more complicated acids, but which, as it were, always
undergo “further development” in only one determined and narrowly
restricted course. Here, as with the organism, the number of possible
variations is very great, but is nevertheless limited, since “what
can or cannot arise is determined beforehand by certain hypothetical
properties of the molecule.”]
[291] “Origin of Species.” 4th German ed., p. 19; 5th English ed., p. 6.
[292] [Mr. A. R. Wallace, in his article last referred to, quotes some
most valuable measurements of mammals and birds, showing the amount of
variation of the different parts. These observations were published
by J. A. Allen, in a memoir “On the Mammals and Winter Birds of East
Florida,” &c. (Bulletin of the Museum of Comparative Zoology at Harvard
College, Cambridge, Mass., vol. ii. No. 3.) R.M.]
[293] [See note 142, p. 310. R.M.]
[294] “Die Darwin’sche Theorie,” Dorpat, 1875.
[295] [A certain number of instances of mimicry are known to occur
between species both of which are apparently nauseous. A most able
discussion of this difficult problem is given by Fritz Müller, in the
case of the two butterflies _Ituna Ilione_ and _Thyridia Megisto_, in
a paper published in _Kosmos_, May, 1879 (p. 100). The author shows by
mathematical reasoning that such resemblances between protected species
can be accounted for by natural selection if we suppose that young
birds and other insect persecutors have to learn by experience which
species are distasteful and which can be safely devoured. See also
Proc. Ent. Soc. 1879, pp. xx-xxix. R.M.]
[296] See Haeckel’s “Generelle Morphologie,” ii. 107.
[297] “Über die Berechtigung der Darwin’schen Theorie,” Leipzig, 1868.
[298] “Populäre wissenschaftl. Vorträge,” vol. ii., Brunswick, 1871, p.
208.
[299] “Das Unbewusste vom Standpunkte der Physiologie u.
Descendenztheorie,” Berlin, 1872, p. 89. The second edition appeared in
1877, in Von Hartmann’s own name.
[300] “Über die Berechtigung,” &c., Leipzig, 1868. In this work will be
found briefly laid down the theoretical conception of variability here
propounded somewhat more broadly. [In the last edition of the “Origin
of Species” Darwin states, with respect to the direct action of the
conditions of life as producing variability, that in every case there
are two factors, “the nature of the organism and the nature of the
conditions.” 6th ed. p. 6. R.M.]
[301] [Although hardly necessary to the evolutionist, it may perhaps
be well to remind the general reader, that all experiments upon
spontaneous generation, or abiogenesis, have hitherto yielded negative
results; no life is produced when the proper precautions are taken for
excluding atmospheric germs. But although we have so far failed to
reproduce in our laboratories the peculiar combination of conditions
necessary to endow colloidal organic matter with the property of
“vitality,” the consistent evolutionist is bound to believe, from
the analogy of the whole of the processes of nature, that at some
period of the earth’s history the necessary physical and chemical
conditions obtained, and that some simple form or forms of life arose
“spontaneously,” _i.e._ by the operation of natural causes. R.M.]
[302] See Haeckel’s “Generelle Morphologie,” vol. ii. p. 203, and
Seidlitz, “Die Darwin’sche Theorie,” 1875, p. 92 _et seq._
[303] [In a recently published work by Dr. Wilhelm Roux this author has
attempted to work out the idea of an analogy between the struggle for
existence and survival of the fittest in individuals and species, and
the struggle for existence and survival of the parts in the individual
organism. See “Der Kampf der Theile im Organismus: ein Beitrag zur
Vervollständigung der mechanischen Zweckmässigkeitslehre,” Leipzig,
1881. R.M.]
[304] [Eng. ed. Meanwhile it has been shown by Oscar Schmidt that
Von Hartmann, under the name of “the Unconscious,” re-invests
the old vital force with some portion of its former power. “Die
naturwissenschaftlichen Grundlagen der Philosophie des Unbewussten,”
Leipzig, 1877, p. 41.]
[305] _Loc. cit._ p. 175.
[306] _Loc. cit._ p. 156.
[307] “Über die Cuninen-Knospenähren im Magen von Geryonien.” Reprint
from “Mittheil. des naturwiss. Vereines,” Graz, 1875.
[308] [See Darwin’s “Origin of Species,” 6th ed. pp. 33, 34, and
201-204. R.M.]
[309] [Eng. ed. See Kant’s “Allgemeine Naturgeschichte und Theorie des
Himmels.”]
[310] “Das Unbewusste vom Standpunke der Physiologie und
Descendenz-Theorie,” Berlin, 1872, p. 16.
[311] [Eng. ed. See Lotze’s “Mikrokosmos,” 1st ed., vol. iii. pp.
477-483.]
[312] See Helmholtz’s “Populäre wissenschaftl. Vorträge,” vol. ii.,
Brunswick, 1872.
[313] See also Fr. Vischer’s “Studien über den Traum. Beilage zur
Augsburger Allgem. Zeitung,” April 14th, 1876. Haeckel also includes
this idea in his recent essay already quoted, “Die Perigenesis der
Plastidule,” Berlin, 1876, p. 38 _et seq._
[314] See Von Hartmann, _loc. cit._ p. 158.