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MANUAL OF ENTOMOLOGY.

■H. Spry, de&

F. F. Bccfor, sc.

MANUAL OF ENTOMOLOGY,

TRANSLATED FROM THE GERMAN OF

DR. HERMANN BURMEISTER.

W. E. SHUCKARD, M.E.S.

WITH ADDITIONS BY THE AUTHOR, AND ORIGINAL NOTES AND PLATES
BY THE TRANSLATOR.

MORMOLYCE PHYLLODES.

LONDON :

EDWARD CHURTON, PUBLIC LIBRARY, 26, HOLLES STREET.

1836,

LONDON !

BRADBURV AND EVANS, PRINTERS, WHITEFRIARS.

PREFACE.

Upon completing the Translation of this ( Manual,’ it is
incumbent upon me to thank the press generally for the very
favourable reception it has obtained throughout its progress. It
was undertaken with the view to contribute to the advancement
of the study of Entomology, by giving a wider circulation to its
elementary principles ; and it is hoped that its interesting details
will tend to diffuse a taste for its more general cultivation.

Amidst a multitude of original experiments and observations,
in addition to its numerous other scientific claims, this work will
be found to comprise, in its anatomical and physiological depart-
ments, a generalisation of the host of facts elicited by the laborious
investigations of Straus Durckheim, Miiller, Suckow, Leon
Dufour, Nitzsch, &c. &c., up to a very late period. It is
confidently believed, that a book combining the researches of
such eminent men must necessarily become extremely useful,
not only to the entomological but also to the physiological student,
and to the scientific man in general.

The advantages to be derived from the study of natural
history are manifest. One of its most conspicuous merits, and
that upon which the immortal Cuvier particularly dwelt, is its
tendency to methodise the mind, by impressing it with a habit of

PREFACE.

order and precision ; thus, having all the effect, but under a
more alluring mask, of the abstract mathematics, and the logic of
the schools. This character attaches more peculiarly to that
portion of natural history upon which this work exclusively
bears — namely, the study of insects. Their great multitude
and diversity, their brilliancy of colour, eccentricity and extreme
elegance of form, their metamorphoses, complexity of structure,
and peculiarities of habits, always adapted to the purposes they
have to accomplish in the economy of nature, altogether unite to
give an intense interest to this delightful pursuit.

Having thus summarily shown the value of the work, and the
utility and pleasure to be derived from the study of the science,
it only remains for me to add my best thanks to Dr. Burmeister
for the promptitude with which he spontaneously supplied me,
upon hearing of my undertaking, with the new MS. of several
portions wherein his opinions had become modified or changed.

THE TRANSLATOR.

TABLE OF CONTENTS.

PAGE

Introduction— Definition and Compass of Entomology, §§ ]— - 4 . . 1

FIRST DIVISION.

GENERAL ENTOMOLOGY.

FIRST SECTION. — ORISMOLOGY.

Its Definition and Compass, §§ 5—7 . . . .5

FIRST CHAPTER.

General Principles, §§ 8—13 . . . . . 7

SECOND CHAPTER.

General Orismology, $ 14 . . . . .11

I. Form, §§ 15— 21 . . . . 11

II. Quality, §§ 22 — 24 . . . . .16

III. Clothing, §§ 25, 26 . . . . . 19

IV. Colour, §§ 27—38 . . . . .20

V. Measure, 39 — 42 . . . . . 26

VI. Affixion, Direction, §§ 43 — 45 . . . .28

TABLE OF CONTENTS.

THIRD CHAPTER.

Partial Orismology, 46, 47

I. The Egg, §§ 48—50

II. The Larva, $$ 51-58

III. The Pupa, §§ 59-64

IV. The Imago, § 65

1. The Head, $$ 66 — 7%

The Mouth, $$ 68—70 .

The Eyes, § 71

The Antennse, § 72

2. The Thorax, §§ 73—78

Organs of Motion on the Thorax.

A. The Wings, §§ 79, 80

B. The Legs, §§ 81—83

3. The Abdomen, §§ 84, 85

PAGE

. 30
. 31
. 33
. 43
. 48
. 49
. 51
. 62
. 63
. 71

. 91
. 100
. 108

SECOND SECTION.— ANATOMY,

Idea and Subdivision of it, §§ 86 — 90 . . . - 114

FIRST SUBSECTION.— VEGETATIVE ORGANS,

Their general Character, §§ 91— 94 . . . 117

FIRST CHAPTER.

THE ORGANS OF NUTRITION.

I. The Intestinal Canal and its Appendages, §§ 95 — 114 . 119

II. The Fatty Substance, § 115 . . , . 151

III. The Blood-vessels, §§ 1 16— 121 . . . 153

IV. The Organs of Respiration, §§ 122 — 130 , , 158

TABLE OF CONTENTS. ix

SECOND CHAPTER.

THE ORGANS OF GENERATION.

PAGE

Their general Character, §§ 131 — 134 .... 181

I. Female Organs of Generation, §§ 135— 145 . . . 184

II. Male ditto, §§ 146—152 . . 200

III. Development of the Sexual Organs during the Metamorphosis,

§ 153 . . ... 220

IV7. Conformity of the Female and Male Sexual Organs, § 154 . 222

SECOND SUBSECTION.— THE ANIMAL ORGANS.

Their general Character, §§ 155—157 . . . . 224

THIRD CHAPTER.

THE ORGANS OF MOTION.

I. Of the Horny Skeleton, §§ 159 — 168 . . . 226

II. The Muscular System, §§ 169 — 181 . . . 247

FOURTH CHAPTER.

THE ORGANS OF SENSATION.

Their general Division and Character, § 182 . . . . 269

I. The Brain, §§ 183—185 ... 272

II. The Ventral Cord, §§ 186—188 . . . 277

III. The Sympathie System, §§ 189 — 191 . . . 286

IV. The Organs of the Senses, §§ 192—198 . . 289

THIRD SECTION.— PHYSIOLOGY.

Its idea and subdivision, §§ 199—200 .... 302

FIRST SUBSECTION. — SOMATIC PHYSIOLOGY.

Its idea, § 201 . . . . . 304

TABLE OF CONTENTS

FIRST CHAPTER.

PAGE

Of Generation, §§ 202-213 . - . . -306

SECOND CHAPTER.

Of Nutrition.

Its general character and kinds, §§ 214— 216 . . . 344

I. Digestion, §§ 217—225 .... 347

II. Respiration, §§ 226— 236 . • • 384

III. Circulation of the blood, §§ 237— 243 . . . 403

THIRD CHAPTER.

The Metamorphoses, §§ 244—260 . . • 414

FOURTH CHAPTER.

The Muscular Motion, §§ 261—267 .... 445

FIFTH CHAPTER.

The Sounds emitted by Insects, §§ 268—271 . . . 466

SIXTH CHAPTER.

Of Sensation and the Senses, §§ 272 — 278 . . . 474

SEVENTH CHAPTER.

The Luminousness of Insects, §§ 279—282 . . 490

SECOND SUBSECTION.— PSYCHOLOGICAL PHYSIOLOGY.

The Nature and Object of Instinct, §§ 283—286 . . . 498

EIGHTH CHAPTER.

THEIR SELF-PRESERVATION.

I. Means of Defence, § 288 . . . . . 504

II. Instinct of Nutrition, §290 . . . . 511

TABLE OF CONTENTS.

NINTH CHAPTER.

THEIR MEANS FOR THE CONSERVATION OF THE SPECIES.

PAGE

Sexual Instinct, § 291 . . . . .513

I. The Copulative impulse, § 292 . . .513

II. Affection for their young, §§ 293— 299 . . . 515

THIRD SUBSECTION.— RELATIONS OF INSECTS TO
THE EXTERNAL WORLD.

Compass of this relation, § 300 . . . 537

TENTH CHAPTER.

IN RELATION TO OTHER ORGANIC BEINGS.

To Plants, §§ 301—306 . . . .538

To Insects, § 307 . . . 552

To Birds, § 308 ... . . 554

To Mammalia, § 309 . . . . . 556

To Man, § 310 . . . .558

ELEVENTH CHAPTER.

Relation to the Elements and Seasons, §§ 311 — 313 . . . 565

TWELFTH CHAPTER.

Relation to the Antediluvian World, §§ 314— 317 . . . 574

FOURTH SECTION.— TAXONOMY.

FIRST CHAPTER.

General ideas — Nature of Artificial and Natural Divisions, §§ 318—321 582

I. Idea of Species, §§ 322 — 324 . . . 588

II. Idea of a Genus, §§ 325—331 . . . 590

III. Idea of the Higher Groups, §§ 332 — 336 . . 594

Xll

TABLE OF CONTENTS.

SECOND CHAPTER.

HISTORY OF THE PRINCIPAL SYSTEMS.

PAGE

Earliest essays, Aristotle, § 337

. 597

More recent ones, §§ 338 — 343

. 598

Zootomical systems, §§ 344—349

. 608

Physiological systems, §§ 350—352

. 617

THIRD CHAPTER.

Nomenclature, §§ 353 — 363

. 624

INTRODUCTION.

DEFINITION AND COMPASS OF ENTOMOLOGY.

§ 1.

Natural History has for its object the inquiry into the being of
natural bodies and their thorough investigation in reference to their
various qualities, and the relative functions of their component parts.
Understood in this extent, it presents us with a distinct unique entirety,
which treats the natural body as complete, but gradually perfected ;
and at the same time seeks to discover the means whereby it attained
its completion and perfection. Natural History, therefore, is no mere
description of form, — no description of nature, as it has been, latterly,
very ‘incorrectly considered, but a true, and pragmatical history,
developed from its own fundamental principles.

Entomology is that branch of this extensive science, which treats
of the Natural History of Insects.

Insects are animals with articulated bodies divided into three chief
portions, the head, thorax, and abdomen ; they have three pairs of legs,
and generally two pairs of wings, and, to acquire this structure, pass
through several transformations and changes, called their metamorphoses.

The object of Entomology, consequently, is to investigate the nature
of insects ; its design is to show how the insect is organised and formed,
and why it was obliged to adopt this particular conformation and internal
structure ; and when this is accomplished, it proceeds to the generalisa-
tion and development of the various vital phenomena observable in the
class. Its view is, however, not limited here to show the mere gene-
ral form of the body of the insect, but it also displays how this general

INTRODUCTION.

form varies in the several orders of insects, and how far this transfor-
mation and change may extend without destruction to its identification.

This comprises, therefore, a summary of the essential purpose of the
science. The chief incentive to our study, and investigation, of natural
bodies in general, is the instinctive impulse of the human mind towards
progressive information, and the extension of the circle of its knowledge;
but, in this pursuit, a multiplicity of useful discoveries are made, which
are applicable to daily life, and which distinctly show the evident
advantages of the science, although their elicitation can never be consi-
dered the primary object of scientific research. The study of insects
will likewise be found rich in sifnilar results, which I shall state in its
appropriate place.

§ 2.

Thus, the Natural History of Insects falls into two great divisions —
viz. the introductory, or general portion, and the particular, or systematic
Natural History of them.

The former, or general division, acquaints us with insects with respect
to their exterior construction, and with regard to their interior organ-
isation ; it also instructs us of the various phenomena displayed by this
class of animals ; and lastly, developes the principle upon which insects
must be arranged, and naturally subdivided. The following divisions
are thence deduced: —

1. The OitisMOLOGY, generally called the Terminology *, which
contains the various technical terms used in explaining the perceptible
differences in the body of an insect, and at the same time acquaints
us with its exterior visible parts in the several periods of its existence,
until its full and perfect development.

2. The Anatomy, or, as it has been called, in reference to the
dissection of insects, Entomotomy, which acquaints us with their in-
ternal construction, and with the form as well as texture of their organs.

3. In their Physiology we learn the functions of these organs.
Besides which, it generalises the multifariously varied phenomena dis-
played by these animals, and re-examines, under a general view, those to
which we are accustomed to apply the name of instinct.

* Kirby lias introduced the term Orismology in lieu of the hybrid compound
Terminology, but which being derived from 'opurpos ( terminus , definitio) should be
written Horisinology. But as it is not unusual to reject the spiritus asper , we have
retained his orthography.

INTRODUCTION.

4. This is succeeded by their Taxonomy, or principles of arrange-
ment, which, after giving its general rudiments, proceeds with a critical
survey of the most remarkable Entomological systems.

§ 3.

The second or particular division of Entomology, contains merely
the description of the insect world, from their highest to their lowest
sub-divisions, in the mode most consonant with system and their scien-
tific definition. It is this portion which is generally called systematic
Entomology, or plainly Entomology, and which is both the most com-
prehensive, and most varied portion of the whole science.

§ 4.

These, therefore, are the several divisions of which the complete
Natural History of Insects consists ; they are all closely connected
together, and produce, only by their strict union, that harmonious en-
tirety of which the science boasts; whereas, the several parts, considered
separately^ form but dislocated fragments, each of which, without the
elucidation of the rest, must frequently remain incomprehensible. The
subdivision of insects into orders, groups, and families, does not properly
belong here, but will find its true situation much lower, where we pur-
pose passing to the particular description of the individuals of this class ;
but as, in the course of the following treatise, we shall so frequently
have occasion to refer to the several orders, it will perhaps be consi-
dered not inapposite, particularly as it may assist the judgment of
Tyros, if we here lay down the distribution into groups. It may remain
here merely intercalated by anticipation.

The commencement of this introduction has already defined what an
insect is ; all animals comprised in it may be thus classed into

A. — Those with an imperfect metamorphosis, i. e. larva, pupa, and
perfect insect, strongly resembling each other, the pupa possessing loco-
motion and eating.

a. having a suctorial mouth.

1. ORDER. — Hemiptera. — ( Cimices , Bugs, fyc.)

b. having a masticating mouth.

a. Four unequal wings, the superior ones pergameneous, the
inferior generally larger, and membranous ; the latter are
folded in repose.

b 2

INTRODUCTION.

2. ORDER. — Orthoptera. — ( Locusts , Grasshoppers, fyc.)

h. Four sometimes equal, sometimes unequal membraneous
wings with reticulated nervures, but never folded.

3. ORDER. — Dictyotoptera. — ( Cockroaches .)

B. — Those with a perfect metamorphosis. The larva is a long maggot,
caterpillar, or wornil. The pupa generally quiescent, and does not eat.

a. Some have a suctorial mouth.

a. Insects with two naked transparent wings.

4. ORDER.— Diptera. — {Flies.)

h. Insects with four large wings, covered wholly, or partially,
with broad scales.

5. ORDER. — Lepidoptera. — {Butterflies, Moths.)

b. The others have a masticating mouth, or at least visible man-

dibles and palpi.

a. Four equal wings, with reticulated nervures.

6. ORDER. — Neuroptera. — {Dragon Flies, #c.)

h. Four unequal wings, with the nervures variously branching.

7. ORDER. — Hymenoptera. — {Bees, Wasps, Ichneumons, §c.)

c. Four unequal wings, the superior ones consisting of a corneous
case.

8. ORDER. — Coleoptera. — {Beetles.)

Note. — Throughout almost all the orders there are apterous families
genera, and species, which are very easily referred to their orders from
their metamorphosis, and the structure of their mouths, but they never
form correctly a distinct one, as Latreille insists, and which he calls
Aptera.

FIRST DIVISION.

GENERAL ENTOMOLOGY.

FIRST SECTION.

ORISMOLOGY.

ITS DEFINITION AND COMPASS.

§ 5.

In a science, which, like Natural History, has to distinguish such
multifarious, and, frequently, such closely approximate forms, it is of
great importance that the differences perceptible to the eye should
be explained by a suitable selection of precise terms, and in a clear,
concise, and readily comprehensible language. Since the recognition
of this principle, a kind of conventional agreement has been aimed
at, whereby the Latin language still retains, at least in the descrip-
tive natural history of the animal and vegetable kingdoms, that
degree of importance which it acquired by its introduction as the
universal language of the learned. The technical language of natural
history thus therefore originated ; for, in the course of progressive
investigation, new terms were required to characterise the newly dis-
covered parts.

§ 6.

Following the example of early writers, whenever the Latin lan-
guage is deficient in the characteristic expression, we apply to the
Greek, and endeavour to derive from it an appropriate name, or form

GENERAL ENTOMOLOGY.

one from it by composition. From the euphony of its words, and the
fulness of its tone, it is peculiarly adapted to the construction of
permanent names of general importance, and has therefore found a
suitable application in the naming of newly discovered orders, families,
and genera. In the construction of these names, however, we must
be exceedingly careful not to wound the spirit of the language by
barbarisms, grammatical inaccuracies, and hybrid compounds (< s.g .
Bitoma, Biphyllus, Taxicornes , &c.), of which, unfortunately, too many
disagreeable examples could be cited. But it is decidedly wrong to
retain these inaccuracies, although such words may have derived a
certain authority from their age, from the mere accident of the inad-
missible nature of their composition not being previously discovered.
The love of truth and correctness demands that such blemishes should
be expunged, wherever they are found, and they can never be subject
to other considerations ; for esteem for their authors, which they may, in
other respects, justly merit, must not prejudice us in their favour.

§ 7.

The technical language of Entomology is subdivided into three parts,
which may be here concisely indicated.

The first chapter contains the important and indispensably neces-
sary general rules and principles for properly naming newly discovered
parts.

The second chapter treats of the general qualities of all, or many
organs, which are comprehensible without a knowledge of their peculiar
forms ; but, on the contrary, in the description of the latter, must be
frequently referred to. The differences of colour, and of clothing,
annex themselves hereto. General Orismology.

In the third chapter I shall explain the various parts and organs
of the body of an insect, as well as their peculiar differences. Partial
Orismology. — (Kirby s Exterior Anatomy .)

GENERAL PRINCIPLES.

FIRST CHAPTER.

GENERAL PRINCIPLES.

§ 8.

Although we here, at once, declare ourselves opposed to an unne-
cessary multiplication of orismological terms, yet we do not mean
that the determinate distinction of particular parts should be rejected,
whenever they are decidedly important. On the contrary, it is the
very first requisite of a precise orismology to apply an exclusively
proper term to each constantly distinct and peculiar part. It will
certainly appear often difficult to restrain oneself within exact limits,
particularly as there are but few other general principles to guide us
than a certain, judicious, and intuitive tact. We will, however, com-
mence by endeavouring to lay down a few principles as rules to be
observed.

§ 9.

I. — Every decidedly different organ, or, where it appears necessary,
every portion of an organ, should receive a name exclusively peculiar
to itself.

II. — This naming, however, must not be arbitrarily exercised; but the
organs of the superior animals must be consulted, and their analogical
structure examined in the insect *.

* The greatest mistakes have, at all times, been made in opposition to this principle,
and yet it is as absolutely necessary, and as strictly founded in the very nature of the thing,
as any. It has doubtlessly occasionally proceeded from an ignorance of the anatomy of the
higher animals ; perhaps, also, from the love of innovation of many writers, that the most
singular interpretations have been made, — names having been applied to parts, or merely
portions of organs, which, strictly, could be applied only to very different organs. To call
that part, the neck (collurn), which bears the legs, is absolutely absurd. Even Fabricius’s
division of the body of an insect into caput , truncus, and abdomen , is wrong, as every
one who knows anything of anatomy must admit that the truncus includes the abdomen.
In the course of our observations we shall detect many similar inconsistencies, but we have
generally considered it unnecessary to take further notice of them, confiding in the correct
judgment of the reader. We have, indeed, endeavoured to retain, as far as was possible,
what has been already done ; but we make it a rule to adopt nothing that is false, whatever
may be its antiquity, and notwithstanding its toleration by the great masters of the science.

GENERAL PRINCIPLES.

§ 10.

III. — Great caution must be exercised in the naming of different
parts in the several orders, as, frequently, the same organ in the
different groups takes a very different form. If particular names
were applied to such modifications, it would tend to mislead, by giving
the appearance of different parts to one and the same. Nor is the
reverse of this admissible, for different organs must not bear the same
name *.

§ n.

IV. — The names of parts should be derived, in prefereuce, from
Latin, but it is advisable in those parts which have always been
signified by Greek terms, to retain them, and introduce new Greek
ones whenever new parts are discovered within the limits of the
particular organs f .

V. — Peculiar organs, which, nevertheless, can only be considered as
variations of a long known typical form, are best distinguished by an
adjective expressive of the peculiarity.

E. g. The legs are called pedes; when adapted to the seizing of prey
they are suitably called pedes raptorii, not arms ( brachia ) according to
Kirby. The idea of arms presumes a certain organisation which is
never found in insects, although the raptorious legs of insects may
possibly be analogous in their functions. But it is certainly incorrect
to call the anterior legs of insects in general arms ; we might just as
rationally call the fore legs of quadrupeds arms. Swimming legs are
thus called pedes natatorii, but not fins (pinnte).

* Fabricius made a mistake of this kind, in applying to what he had called truncus , in
the Coleoptera, the name of thorax , in the Hymenoptera and Diptera ; and, in calling by
the latter term the anterior portion only of the same part, in the Coleoptera, Hemiptera,
and Orthoptera. As in each of the orders of insects, the thorax consists of three parts,
which have been distinguished as prothorax, mesothorax, and metathorax, it is evidently
incorrect to call that collar e, in the Hymenoptera, which is called prothorax in the
Coleoptera, Hemiptera, and Orthoptera ; for the same orismology must be applied to every
order. Reasoning upon the same principle, we cannot see why that portion of the head
should be called hypostoma, in the Diptera, which, in the other orders, has long been
indicated by the name of clypeus.

f It consequently appears preferable to us to call the first segment of the thorax the
prothorax , rather than collar exclusive of the greater precision and comprehensibility of
the first term.

GENERAL PRINCIPLES.

VI. — In many such cases, however, where the substantive is borrowed
from the Greek, a new word is formed by the compounding of two,
e. g . hemelytra, prothorax, &c.

§ 12.

VII. — All fluctuating qualities of one and the same part are distin-
guished by adjectives, and indeed by such as, according to grammatical
use, are customarily applied to such variations.

But the form of the adjectives, which express particular kinds of
qualities, vary chiefly in their terminations. The following are important
for our use : —

1 . The termination in atus and itus, shows merely the existence of
something in general : for ex. antennatus, provided with antennae ;
alatus, winged; sulcatus , with longitudinal furrows ; auritus , furnished
with ears (two little appendages).

2. The terminations in aceus and icius express a resemblance to a
material ; those in eus indicate the material itself : for ex. membranaceus ,
resembling skin; membraneus , skin itself ; coriaceus, leathery ; lateri-
cius, resembling bricks (in colour).

3. The termination osus expresses fulness, or the abundant presence
of a quality : for ex. pilosus, covered with much hair ; setosus, covered
with stiff bristles ; squamosus , covered with scales.

4. The termination ius expresses the uses or aptness of an organ :
for ex. raptorius, adapted to seize prey ; fossorius , fitted for digging ;
natatorius, suited to swim, &c.

5. The deficiency of a usually present quality is indicated by placing
in front the a privative in the Greek, and the preposition e , eoc, or in,
in Latin words : for ex. apterus , without wings ; escutellatus , without
a scutellum ; inermis, unarmed.

6. To express quantity or particular distinctness, the superlative
degree of comparison is used, or the words valde , maxime , distincte , are
prefixed: for ex. ,v quamosissimus, densely covered with scales; rugo-
sissimus, very uneven ; disiincte-punctaius , very clearly covered with
punctures.

7. The indistinctness of a quality is expressed by prefixing the word
obscure , or by uniting the preposition sub to the adjective. But
diminutives are not unfrequently used : for ex. obscure-ceneus , of an
indistinct bronze colour ; subpunctatus , slightly punctured ; substriatus ,
slightly striated; hirsuiiusculus , somewhat hairy.

GENERAL PRINCIPLES.

8. To express a quality which is directly the reverse of the usual
signification of the term, the particle ob is added, and we say, for ex.
obconicus, of the shape of a reversed cone ; viz., when a part, instead of
running from the base upwards to a point, runs from the apex down-
wards to the point ; obovaius is used in the same way to express its
being of a reversed egg-shape.

9. Qualities which consist of the conjunction of two generally
separated peculiarities are also expressed by the union of both the
adjectives. In composing these words we must be particularly cautious
in the succession of the united terms, as it is by no means indifferent.
The word expressive of the dominant quality stands last, and that made
to precede it is merely its modification: for ex. punctatus indicates
being covered with punctures; siriatus , having linear longitudinal
impressions. By the various compounding of these two words, very
different ideas are formed, according to their precedence. Striato-
punctatus indicates a surface which is merely punctured, but the
punctures whereof are placed in rows ; punctato-strialus, on the
contrary, is a surface which has distinctly impressed lines with punc-
tures within.

§ 13.

VIII. — Parts which discover a certain resemblance of form with
objects, which, by their application, or uses in common life, are suffi-
ciently known, are suitably named from what they accord with. Many
adjectives thence occur in Orismology which require no further expla-
nation. This is not so usual in the terms expressive of colour, and
particularly where it is desirable to explain the multifarious transitions
of one into the other, we meet with difficulties in the selection of the
exactly appropriate word, so that peculiar orismological terms are
requisite for their correct definition.

GENERAL ORISMOLOGY.

SECOND CHAPTER.

GENERAL ORISMOLOGY.

§ 14.

This portion of Orismology has not the advantage of a consecutive
arrangement derived from the nature of the objects contemplated, for
it can be regarded only as consisting of a mass of equivalent ideas, with
their applicable and variable attributes. But the best arrangement
appears to be that of passing from the most general to the more partial
terms ; we have thought, therefore, but without wishing to prescribe it
as necessary, that the most agreeable mode would be to proceed from
the general form of parts to the differences of colour, clothing, size,
direction, &c.

I. — The Form.

§15.

The differences of form may be considered, doubtlessly, as the most
multifarious throughout the whole class of insects ; it will not there-
fore surprise that this portion of Orismology is very rich in terms. But
even this very great diversity leads us to conclude that certain forms
are peculiar to a few organs only. All distinctions, therefore, which
have merely this restricted application, are necessarily excluded from
our immediate general consideration.

§ 16.

If we take any part and contemplate it in its natural connexion with
the rest of the body, the following portions may be clearly distinguished
in it : —

Base (basis), that portion whereby it is affixed to the body.

Atex (apex), that which is opposed to the base.

Contour (peripheria), a portion whereof is the margin (mar go).
According to its situation, this is distinguished into anterior margin,
that which is directed towards the head of the insect ; posterior margin,
that directed towards its tail ; and lateral margins, those intervening
between the anterior and posterior.

GENERAL ORISMOLOGY.

Superior surface ( superficies externa), the inferior surface
{sup. interna), the centre of the superior surface or disc {discus), the
border surrounding the disc or limb {limbus).

Angle {angulus), is that portion where two parts or the margins of
one meet ; sinus {sinus), is a curved break in an otherwise straight
margin; keel {carina), is a sharp, longitudinal, gradually rising
elevation upon the inferior surface.

§ 17.

Besides these general definitions, which may be applied to all or very
many organs, the differences of form may be contemplated under the
following heads : —

1. — Differences of Surface.

2. — Differences of Solids.

3. — Differences of Margin.

4. — Differences of Apex.

5. — Differences of Base.

§ 18.

Figure of the Superficies .

Circular {rotundum, circulare), is a round surface with its diameter
equal on all sides.

Rounded (: rotundate ), when the margins pass gradually into each
other, and not meeting in sharp angles.

Oval {ovale), a rounded surface, its two right angular diameters
being of an unequal length, so that its longest transverse diameter does
not pass through the middle of its longitudinal diameter, but lies
nearer to one end.

Elliptical {ellipticum), allied to the preceding, but differing, inas-
much as that its greatest transverse diameter passes through the centre
of the longitudinal.

Lanceolate {lanceolatum) , when the base is not so broad as the
centre, and the lateral margins slightly, but equally, swollen, gradually
tapering towards the apex, where it terminates in a point, and the
longitudinal diameter more than three times the length of the transverse.

Linear {lineare), a figure having the lateral margins very close
together, and parallel throughout.

Half-moon shaped {lunare), a figure formed by the portion of a
circle cut off by the segment of a larger circle.

GENERAL ORISMOLOGY.

Heart-shaped ( cordalum ), a triangular figure, having its base
emarginate, lateral angles rounded, and lateral margins slightly swollen.

Kidney-shaped ( reniforme ), is a half-moon shaped figure, with its
angles rounded, and its concave margin emarginate.

Triangular {trianguläre) , when the margins meet in three angles.

Square (quadratum), when the four straight parallel margins are of
equal length.

Quadrangular (quadr angulare), when two of the margins are of
unequal length.

Oblong {oblongum, parallelogramum), a square with two of the
parallel margins equal, but longer than the other two equal parallel ones.

Angular (angulatum) , when the angular margins do not exclusively
elbow outwards, but also inwards.

Falcate ( falcatum ), a figure formed by two curves bending the
same way, and meeting in a point at the apex, the base terminating in
a straight margin, resembling a sickle.

Spatulate {spatulatum), a figure commencing with a narrow base,
gradually widening by the lateral margins sloping out, and terminated
at the extremity by a sudden straight line, (the antennas of many
Tachina and other Diptera).

Lozenged ( rhomboidal ), a quadrangular figure, with two opposite
angles acute and two obtuse.

§ 19.

Forms of Bodies.

Spherical ( globosum , sphaericum ), a round body, having all its
diameters equal.

Hemispherical {semiglobosum, hemisphcericum), a round body,
terminated on one side by a flat circular surface.

Lenticular {lenticular e), a round body, with its opposite sides
convex, meeting in a sharp edge.

Conical {conicum), a round body, the base of which is a flat circle
and the apex a point.

Subulate {subulatum), a long thin cone softly bent throughout its
whole course.

Columnar {teres), a form the circumference of which is always
circular, but its thickness indeterminate.

Cylindrical {cylindricum) , a body with its circumference round,
of indeterminate length, but equally thick throughout.

GENERAL ORISM OLOGY.

Attenuate ( attenuatum ), a cylinder having its transverse diameter
much narrower in one part.

Equal (equate), a substance of variable longitude, but the transverse
diameters of which are equal.

Incrassate ( incrassatum ), much swollen at one portion of its length.

Club-shaped ( clavatum ), a form which gradually increases in
thickness towards its apex, where it is obtuse.

Pear-shaped ( pyriforme ), a similar shape, but with this difference,
that its longitudinal section is spatulate.

Funnel-shaped (infundibuliforme), resembling the last in exterior
form, but scooped out at its apical margin.

Fornicate (fornicatmn), concave within and convex without.

Knotted (nodosum), a longitudinal body swollen at one or more parts.

Angular bodies are distinguished by the number of their sides, viz.
three sided (triquetrum), four sided (telragonum), &c.

Prismatic (prismaticum), an angular body of indeterminate length
but equal thickness.

Pyramidal (pyramidale), a triangular body, the angles of which
all meet in one point.

Wedge-shaped (cuneatum), a body whose horizontal longitudinal
section is quadrate, and perpendicular transverse section triangular.

§ 20.

Differences of Margin.

Entire (integer), a plain, flat, straight, or bowed margin, without
angle or incision.

Arched ( arcuatus ) a margin in the form of a bow.

Sinuate (sinuatus), a margin with a rounded incision.

Waved ( undulatus ), a margin with a series of successive arched
incisions.

Serrate (serratus), with jagged incisions, like the teeth of a saw.

Crenate (crenatus), a margin with indentations, the exterior
whereof is rounded.

Dentate ( dentatus ), when the incisions are larger, causing the
margin to stand forth free and direct like teeth.

Ciliate (ciliatus), when it is occupied with short stiff hairs.

Lobate (lobatus), when the margin is divided by deep undulating
and successive incisions.

Erose (erosus), when from the irregularity of its incisions it appears
gnawed (the margins of the wings of many butterflies).

GENERAL ORISMOLOGY.

Tentaculate ( tcnlaculatus ), when soft tensile excrescences are
found upon the margin {Canlharis, Malachius).

Callous (callosus), a margin which resembles a thick swollen lump.

Marginate {marginatus) , is when the sharp edge is margined, and
surrounds the surface with a narrow border.

Deflexed [deflexus), when this sharp edge is bent downwards.

Dilated ( dilatatus , or amplificatus) , when the sharp marginal edge
extends beyond its usual limits.

Incrassate ( incrassatus ), a margin whose edge is not sharp, but
rounded, and somewhat swollen.

§ 21.

Differences of Base and Apex.

The few distinct differences of the base refer merely to its greater
or smaller width, and robustness.

Angustate (angustatum) , or coarctate (coarctatum) , is where a
part begins with a narrow base, and then dilates and thickens.

Dilated (dilatatum) , a distended part, the transverse diameter of
which is much longer at one particular part, and this peculiarity is
generally found near the base.

The differences of apex are much more varied ; we may enumerate
the following as particularly important.

Truncated ( truncatum ), when a part is limited at the eud by a
straight line or surface.

Rounded ( rolundatum ), when the end takes the form of a segment
of a circle.

Pre morse {preemorsum), when the end appears bitten off or splintery.

Emarginate ( emarginatum ), when the end has an obtuse incision.

Retuse ( retusum ), when the terminal margin has an obtuse im-
pression.

Obtuse ( obtusum ), indicates a rounded termination.

Acute {acutum), when it becomes regularly narrower and terminates
in a point.

Acuminate ( acuminatum ), when this decrease is very gradual,
becoming thereby much longer.

Mucronate {mu cron alum) , when from an obtuse end a fine point
suddenly proceeds.

Cuspidate ( cuspidatum ), when this pointed process is very much
extended, becoming almost setiform.

GENERAL ORISMOLOGY.

II. — Quality.

§ 22.

Although the investigation into structure, and the consequential
qualities of the organs, is more restrictively the object of anatomy ;
yet the precise definition of their various distinctions is of importance
to descriptive entomology. We must not, therefore, omit defining
orismologically these peculiarities of the structure of the parts, and the
more so, as they are chiefly superficial. Under this head we shall
accordingly treat particularly of the differences of substance, and of
those of superficies, excluding however from this chapter those arising
from individual substances springing from, or reposing upon the surface
of bodies, such as hair, scales, &c. &c.

§ 23.

Differences of Substance .

Membranous ( membranaceum ), is a delicate, flexible, transparent,
thin, superficially distended substance.

Coriageus (jcoriaceum) , is also a thin, flexible, distended substance,
but is somewhat thicker, and opaque, resembling leather.

Corneous (corneum), a thicker, harder, entirely opaque, and scarcely
flexible substance, resembling horn.

Cartilaginous ( cartilagineum ), is a substance combined of the
qualities of membrane and horn; it is thicker than the latter, but
somewhat transparent, flexible, and always whitish.

Solid ( solidum ), is a substance consisting of one mass, with no vacant
interstices.

Porous ( porosum ), when small interstices or holes are observable
upon the surface.

Spongy ( spongiosum ), when soft and intersected by small channels
throughout its substance.

Tubular ( tubulorum ), when a longitudinal cylindrical body is hollow
throughout its vvhole length.

Ventricose ( ventricosum ), when this tubular pipe suddenly distends
into a large cavity.

Flexible ( flexilis ), a substance possessing elastic properties.

Rigid ( rigidum ), when it will not bend without breaking.

GENERAL ORISMOLOGY.

§ 24.

Differences of Surface.

Smooth ( laeve ), a surface without either impressions or elevations.

Levigate ( Icevigatum ), a smooth surface, somewhat shining.

Shining ( nitidum , politum), when a smooth surface reflects, as if
formed of metal.

Lucid (lucidum), possessing this quality in a high degree, reflecting
with the brilliancy of a mirror.

Scabrous ( scabrum ), a surface covered with small and slight
elevations.

Rough ( asperum ), when these elevations are more perceptible.

Verrucose ( verrucosum ), a surface beset with large smooth ele-
vations, resembling warts.

Torulose ( torulosum ), when there are but few elevations spread
about, but these of considerable size.

Granulated ( granulatum ), when small roundish elevations are
placed in rows ; muricate ( muricatum ), when dispersed elevations rise
in sharp points; echinate ( echinatum ), when they rise higher, and
are thinner ; catenulated ( calenulatum ), when longitudinal eleva-
tions are connected like the links of a chain, and are placed in rows ;
intricate (inlricatum) , when the elevations and depressions are placed
without any regularity, but close to each other ; papillulate (papil -
lulatum), when the dispersed elevations or depressions have a smaller
elevation in their centre.

Lineate ( lineatum ), when there are fine longitudinal elevated lines ;
costate ( cosiatum ), when these lines are stronger, and the intervals
between them wider ; furrow ( sulcus ), is such an interval.

Tesselate ( tesselatum ), when the lineate surface is intersected by
similar transverse elevated lines, as it were chequered (it is also used
to indicate square scales); reticulated ( reticulatum ), when the
stronger lines intersect each other like the meshes of a net.

Striated (striatum), when there are parallel longitudinal shallow
impressions ; sulcate (sulcatum) , when these impressions are broader
and deeper than the preceding, or rather when they are of the same
width as the interstitial elevations ; whereas, when striate, these inter-
stices are much wider ; porcate (porcatum), on the contrary, when the
sulcations are deep, and very much broader than the intervening

GENERAL ORISMOLOGY.

elevated ridges ; canaliculate ( canaliculatum ), is a surface, which has
in its centre a broad, but not very deep longitudinal furrows ; exarate
(< ejcaratum ), when several such furrows with perpendicular margins,
and wide, elevated intervals, run parallel to each other ; aciculate
(aciculatum), when many fine, frequently undulating striae running
either parallel, or interweaving each other, make the surface appear as
if scratched with a needle.

Punctured ( punctatum ), a surface covered with small impressed
punctures; variolus ( variolorum ), when larger depressions are iso-
lated, and resemble the maiks of the small-pox; foveolate ( foveo -
latum), or scroeiculate ( scrobiculatum ), when somewhat deeper
impressions become narrower towards their bottom ; clathrate ( clath -
ratum), when such foveoles are placed in rows, having elevated longitu-
dinal lines between them ; favose ( favosum ), when these depressions
stand close together, so that the surface resembles a honey-comb ;
engraved ( exsculptum ), when a variety of irregular longitudinal
depressions cover the surface; vermiculate ( yermiculatum ), when
the depressions are longitudinal and tortuous, like a worm-eaten stem.

The following distinctions are made with respect to the convexity or
concavity of a surface : —

Plane ( planum ), when the whole surface is of an equal height.

Convex (convexum), when a surface rises gradually to its centre,
which becomes thus the highest of the whole.

Concave ( concavum ), when the surface gradually declines towards
its centre, thus becoming the deepest.

Excavated ( excavatum ), a depression, the section of which is not
the segment of a circle.

Gibbose ( gibbosum ), when separate parts rise higher than the rest;
gibbous ( gibbum ), on the contrary, is a surface, the section of which
is not the segment of a “circle ; tuberculate ( tuberculatum ), when
the whole surface rises conically ; rugose ( rugosum ), when longitudi-
nal elevations are placed irregularly like coarse wrinkles.

The inequalities, caused by a production of the true surface, are thus
distinguished : —

Aculeate ( aculeaturn ), with slender pointed processes ; spinose
( spinosum ), covered with solitary, thicker, and frequently bowed pro-
cesses.

Unarmed ( muticum , inerme), when no such processes exist. The
first word is generally used when terminal processes are wanting, where
they are usually present.

GENERAL ORISMOLOGY.

III. — Clothing.

§ 25.

Having thus explained the differences of surface produced within
itself, we have yet to notice those caused by individual substances
lying upon or attached to it.

Glabrous (glabrum), is a uniform surface, without this distinction,
when according to rule hair (pill) clothes it.

Pilose ( pilosum ), when covered with dispersed, somewhat long and
bent hairs.

Hairy ( hirtum , hirsutum ), when densely covered with short stiff hairs.

Villose (villosum), when densely covered with long slender hairs,
which rise upright.

Pubescent (pubescens) , when the hair is soft, short, and decumbent.

Crinite ( crinitum ), when the hair is very long, slender, and dis-
persed.

Sericeous (sericeum, holosericeum) , when short shining hairs lie
closely to the surface, resembling silk or satin in splendour.

Lanuginose ( lanuginosum ), when longish curled hair is dispersed
over the surface.

Tomentose (tomentosum) , when longish curled hair stands densely
and interwoven.

Setose ( setosum ), with dispersed long stiff hair.

Ciliate ( ciliatmn ), when fringed with short stiff hair.

Pinnate ( pinnatum ), when stiff hairs, or thorny processes, occupy
the opposite sides of a thin shank.

Squamose ( squamosum ), when covered with small broad scales which
lap over each other ; such a scale with a short stalk is called squama.
When these scales are square the surface is called tesselated ( tesse -
latum), pruinose ( pruinose ), when covered with minute dust, scarcely
discoverable by the lens ; farinose ( farinosum ), when the dust is more
perceptible, resembling flour, and removed by the least touch ; folinose
( polinosum ), this dust, when yellow, like the pollen of flowers ; pul-
verulent ( pulverulenlum ), rorulent ( rorulentum ), express very
similar, scarcely precisely distinguishable qualities ; lutose ( lutosum ),
apparently or absolutely covered with dirt *; naked (nudum), a surface
without either a scaly or dusty covering.

* Many beetles that live upon a clay soil are always thus covered with dirt ; for
example, the species of the genera Arida , Metern variolosus.

c 2

GENERAL ORISMOLOGY.

§ 26.

If the clothing be placed isolated, leaving free spaces between
it, or if present upon only certain parts of the body, the following
terms are used to distinguish these differences : —

Fasciculate ( fasciculatum ), is a surface covered with dispersed
bundles of long hair ; a solitary one is called a fascicule {fasciculus) ;
cirrus ( cirrus ), is a curled lock of hair placed upon a thin stalk ;
brush ( scopa ), when the hair is short, stiff, and of equal length ;
scopate ( scopaceum ), is a surface entirely covered with such a brush.

Comate ( comatum ), when the upper part of the head or vertex alone
is covered with long hairs.

Barbate ( barbatum ), when a part, chiefly an opening, as the mouth,
&c., is surrounded by long hairs.

Pencillate (jpencillatum) , when long flexible hair is placed upon
a thin stalk.

Fimbriate ( fimbriatum ), when a part is fringed with hair of
irregular length.

Jubate ( jubatum ), when fringed with long pendent hair (interme-
diate legs of the male of Anthophora retusa).

IV. — Colour.

§ 27.

Colour succeeds to form, and the various qualities of surface, as the
next most important character for distinguishing insects. Even in
groups wThere colour cannot be used as a specific character, from its
great and frequent variation in the same species (as Coccinella varia-
bilis, Illig.), it then becomes important to notice precisely its differences
for the requisite separation of the varieties of the species. In order to
explain distinctly these differences of colour, terms expressive of the mul -
titudinous gradations of tint produced by the various admixture of the
several primary colours are necessary. But as we have not yet arrived at
a general unanimity, which may be readily perceived by the comparison
of the descriptions of the same insect by different authors, it is vain to
hope that we shall here solve the problem of reducing the system to
universal harmony. Clearly perceiving these difficulties, Lamarck, and
after him Latreille*, proposed a peculiar method for the definition of
colour, whereby he thought he had removed every possible doubt.

* P. A. Latreille, Histoire Naturelle des Crust, et des Insectes. Paris, an. XII. Vol. i.
p. 331, &c.

GENERAL ORISMOLOGY.

He considered three of the seven prismatic colours as simple primary
colours ; viz. blue, red, and yellow, and adopted them as the basis of
his whole system, seeking their correspondent affinities in nature. Blue
conducts on the one side to black, yellow to white. From the admix-
ture of equal parts of the approximate colours, two new ones arise ; viz.
violet, from blue and red, and orange, from red and yellow ; green is
excluded, it being treated as the unnatural and irregular union of two
colours removed from their true places (!). Thence we have the fol-
lowing series : —

Black, blue, violet, red, orange, yellow, white.

This series he inscribes upon a scale, divided into sixty equal parts ;
he places white at 0, and proceeding from 10 to 10, consecutively
arranges them all. The modification, in the union of two approximate
colours, is determined by their relative numerical power ; for example,
five parts black, and five blue, give black-blue ; eight parts black, and
two blue, give a very deep black-blue (bleu noir triple), &c. By this
means, he obtains sixty different gradations of colour, which, we admit,
frequently suffice for the description of natural colours, but do not Cer-
tainly extend to all, for all unions of black and red, red and white,
black and white, are wanting. This table is also rendered excessively
defective by the entire omission of green, one of the most prevailing
colours, and in the most variable gradations, throughout nature.

§ 28.

Eight primary colours are generally adopted in Natural History ;
viz. white, grey, black, brown, red, blue, green and yellow. Each of
these colours admit of being mixed with others, and even some of those
named are produced by the union of two of the rest. It is, therefore,
evident, how excessively variable must be the effect of such mixtures
of colours, and how very closely they approach to and pass into each
other, so that the precise distinction of each change would be an
ungrateful and useless task.

The degrees and intensity of colour are also very variable.

The following terms are in use to express some of them : —

Deep (saturate), when colour is very intense or thickly laid on.

Pale (dilute), when but slightly coloured.

Bright (Icete), when the colour is clear and vivacious.

Faded (obsolete), when it appears as if faded by the air.

Sordid (sordide), when the colouring is impure, and as if clouded
by the admixture of another.

GENERAL ORISMOLOGY.

§ 29.

White (albus), a pure plain white.

Niveous ( niveus ), the purest, dazzling white of snow.

Lacteous (lacteus), white, with a bluish tint like milk.
Cretaceous ( cretaceus ), white, with a yellowish tint like chalk.

§ 30.

Griseous ( griseus ), a mixture of black and white.

Hoary ( canus , incanus ), grey, with the white prevailing.
Cinereous ( cinereus ), a dark grey, in which the black prevails.
Mouse-coloured ( murinus ), grey, with a yellowish tint.
Fawn-coloured ( cervinus ), grey, with a reddish-brown tint.
Smoky ( fumatus ), grey, inclining to dark-brown, like the colour of
smoke.

§ 31.

Black ( niger ), pure black, the colour of fresh garden-earth.
Blackish ( nigricans ), a bright black, inclining to grey.

Atrous ( ater , aterrimus), the purest, most intense black.
Coal-black (anthr acinus), a deep shining black, with a bluish tint.
Piceous ( piceus ), a bright black, with a greenish tint.

§ 32.

Fuscus (fuscus), dull brown, a plain mixture of black and red.
Brown ( brunneus ), a pure bright brown.

Chestnut ( castaneus ), a bright red-brown, the colour of the fruit
of the horse-chestnut.

Bay ( badius ), a clearer lighter brown than the preceding.
Ferruginous (ferrugineus) , a brown, wherein red prevails, resem-
bling the rust of iron.

Fuliginous ( fuliginosus ), a very deep dark brown, the colour of soot.
Umber ( umbrinus ), a bright dark brown,' with some yellow
Fulvous (fulvus), a light brown, with much yellow.

§ 33.

Red (ruber), the usual red ; the colour of burnt tiles.

Miniatous ( miniatus ), the colour of red lead.

Latericeous ( latericius ), the yellow-red of yellowish bricks.

GENERAL ORISMOLOGY.

Sanguineous (sanguineus) , a deep red, with a dash of blue, the
colour of fresh blood.

Purple (purpureus or puniceus), a bright red,, with a violet tint.

§ 34.

Blue ( cyaneus ), pure dark blue of Indigo.

Azure (azureus), a clear brilliant blue, viz. wings of Lyccena .

Sky-blue (cceruleus) a pale blue, like the colour of the sky.

Violet ( violaceus ), a blue, with a reddish tint.

Pruinose ( pruinus , pruinosus ), a reddish blue, with a whitish
covering, like the bloom of ripe plums.

Glaucous (glaucus), a bright blue, with a strong admixture of
white, inclining to grey.

Cassious (ccesius,) a greenish, grey, sordid blue.

Dark-blue ( atroceruleus ), a dark, deep blue, inclining to black.

§ 35.

Yellow ( flavus ), most beautiful, and purest in the colour of
sulphur, thence sulphureous (sulphur eus) .

Stramineous (stramineus) , a pale, less brilliant, but pure yellow
of the colour of straw.

Saffron-coloured (croceus), or orange (aurantiacus) , yellow,
with an admixture of red.

Ochraceous (i ochraceus ), a similar but sordid yellow, inclining to
brown, the colour of ochre.

Luteous ( luieus ), a brownish yellow, the colour of clay.

Lurid ( luridus ), a dirty yellow, more inclining to brown.

Livid (lividus), a palish yellow, with a blue tint.

Testaceous (testaceus), a dull, yellow brown. .

§ 36.

Green (viridis), the mixture of blue and yellow, the prevalent
colour of the leaves of plants.

GEruginous (ceruginosus), a bright green, inclining to blue.

Prasinous (prasinus), a light green, inclining to yellow.

Olivaceous (olivaceus), a green, with an admixture of brown.

Yellow-green ( flavo-virens ), a bright green, with the yellow
predominant.

GENERAL ORISMOLOGY.

§ 37-

Besides the above terms, expressive of colour, several are used derived
from natural objects, or from those in daily use.

Hyaline ( hyalinus ), expresses a transparent, colourless part.

Pellucid ( pellucidus , diaphanus), a coloured but transparent part.

Opaque ( opacus ), a clouded, not transparent part.

The brilliant or glittering colours are derived chiefly from metals or
other minerals, to which they are exclusively peculiar.

Opaline ( opalinus , or opalizans), the prismatic reflection of the
opal.

Margaritaceous ( margaritaceus ), reflecting the prismatic colours
like mother of pearl.

Crystalline ( crystallinus ), the pure transparency of crystal.

Amethystine (amethystinus) , the brilliant colour of the amethyst.

Smaragdine ( smciragdinus ), the briJliant green of the emerald.

Silvery (argenteus) , the metallic white of silver.

Golden ( auratus , or inauratus ), the metallic yellow of gold.

Aurichalceous ( aurichalceous ), the metallic yellow of brass.

Cupreous ( cupreus ), the metallic red of copper.

AENEOUS ( ceneus ), the green metallic colour of bronze.

Chalybeous ( chalybeus ), the metallic blue of case-hardened steel.

Plumbeous ( plumbeus ), the pale blue grey of lead.

Ferreous ( ferreus ), the metallic grey of polished iron.

Splendent ( splendens ), any colour having a metallic splendour.

§ 38.

There are also peculiar terms to express the painting of parts.

Spot (punctum), a small roundish dark spot upon a plain surface ;
these spots must be distinguished from impressed punctures, but the
latter are sometimes differently coloured from the rest of the surface.

Atoms ( atomi ), are points not proceeding from the colour of the
surface, but applied to the surface ; they must, however, be so large and
distinct that each can be clearly recognised.

Pustule ( pustula ), a point of larger circumference.

Macula (macula), is a tolerably large angular spot, of a dark colour,
upon a uniform surface.

Gutta (gutta), is a light spot upon a light ground, viz. white upon
yellow.

GENERAL ORISMOLOGY.

Litura ( litura ), an indistinct spot, paler at its margins.

Plaga ( plaga ), a longish spot of irregular form.

Line {lined), a very slight, generally straight, but also sometimes
gently bent, differently coloured stripe.

Vitta (i uiita ), a broad longitudinal stripe.

Striga ( striga ), a transverse band.

Fascia (fascia), a broad transverse band.

Annulet (annulus), a narrow differently coloured circle upon a
surface, or upon the circumference of a part.

Lunulet (lunula), a half-moon shaped spot of a different colour.

Ocellus (ocellus), a coloured ring, with a similarly or differently
coloured centre. In the latter case this point is called the pupil
(pupilla), and the space between it and the ring the iris.

From these terms are derived the adjectives of a similar signification,
as j Elytra vittata , &c. Besides these, many adjectives are used to
express similar, but less peculiar painting, such as, —

Irrorate (irroratus), when a space is covered with the above
described atoms.

Nebulöse (nebulosus), when a surface has different, lighter and
darker and paler markings resembling the irregular colouring of a cloud.

Signate ( signatus , or notatus), is a part with distinct markings.

Dispersed ( adspersus , conspersus), when these markings consist of
small spots standing close together.

Fenestrate (fenestratus), is a dark surface, with one or more
transparent spots.

Marmorate (marmoratus) , when the markings are variegated like
marble.

Testudinate (testudineatus), when the surface resembles the back
of a tortoise.

Undulate ( undulatus ), when the markings are waved either
longitudinally or transversely.

Unicolor {unicolor), a part uniformly coloured.

Concolorous (concolor), when resembling in colour to any other
part of the same insect.

Versicoloured (versicolor), when a part displays several different
colours, indeterminately restricted.

Discoloured (discolor), when the same part of an insect has diffe-
rent colours. (For example, legs are called discoloured when the anterior
are red and the posterior black.)

Iridicolor (iridicolor), a surface reflecting the prismatic hues.

GENERAL ORISMOLOGY.

V. Measure.

§ 39.

A universally known measure,, — the Paris line, — the twelfth part
of an inch, has been adopted as unit for the determination of the
length of insects. This character is of considerable importance from
the very constant uniformity of size, not only of the parts of the same
individual, but also of all the individuals of the same species* ; and
thus the length of every possible part can be as precisely ascertained
as the purpose in view may require. This mode of measuring has by
far the advantage, and must consequently never be omitted when a
species is named and published. The difference of size which imme-
diately catches the eye is frequently the first best character whereby
we are enabled, at the very first glimpse, to separate two, or more,
closely related species.

§ 40.

Besides this universally applicable, absolute measure, there is
another relative one. A portion of the insect is adopted as the unit,
and by means of it, the length of the remainder is determined, or two
or more parts are compared together, and thereby a proportional rela-
tion formed. This plan is also useful particularly when given in con-
junction with its absolute length. The following is the mode of
proceeding to the precise determination of the longitudinal pro-
portions.

We must commence by measuring the whole length of the body
and giving it, and then the length and breadth of the different di-
visions must be placed as in the following table : —

HEAD.

THORAX.

ABDOMEN.

Length.

Breadth.

Length.

Breadth .

Length.

Breadth.

0,70

1,0

1,80

2,10

3,50

2,40

Such a table immediately gives the relative proportions of each

* This is liable to innumerable exceptions, but a familiarity with insects soon gives an
idea of the range that it may be allowed, as it varies considerably in different species. It
can never be permitted alone to determine a difference, unless supported by other cha-
racters which, in themselves, sometimes (particularly in colour) would scarcely suffice
for a separation. Its use is consequently of importance for identification, exclusive of its
value in determining the effects of climate and temperature. — Tu.

GENERAL ORISMOLOGY.

chief division to the other ; and it is very easy., by a comparison with
these, to indicate sufficiently the length of the limbs ; as, for example,
we might say of the antennae, as long as head and thorax together ; or
of the wings, they are one-half longer than the abdomen. And the
length of the legs, and their several joints, may also be thus shown.

Hausmann* was the first, as far as we are aware, who applied this
method to insects, and A. Ahrens followed him, and which all writers
of Monographs should likewise do. But it can scarcely be adopted in
a complete system of insects (the want of which is now so strongly
felt upon all sides) by reason of its too great prolixity,. In such a
work, the mere length must suffice, but which must never be omitted.

§ 41.

This precise and elaborate measuring of the parts has been endea-
voured to be dispensed with by the introduction of a comparison with
universally known objects. The width of the thumb (an inch, pollex )
has served for the determination of the length of large individuals.
Half that length is indicated by the adjective half ( dimidius ), which
is universally used to indicate half the size. We thus say half as
large, dimidio minus ; by one-half larger, dimidio majus ; by one-lialf
broader, dimidio latius, &c. In the same manner the comparative
numerals are applied, triplex, quadruplex, &c. Thus, one-third as
large, triplo-minus ; three times as large, triplo-majus ; one-fourth
as large, qua dr uplo -minus ; four times as large, quadruplo-majus .
Quincuplex and sextuplex, are also, but very seldom, used.

§ 42.

Equal size is indicated by the adjective cequalis ; a more con-
siderable size is given generally without precise determination, or by
the expressions super ans and excedens. Very variable size, as well
as the variableness of colour, are indicated by the words variabilis ,
mutabilis.

* Illiger’s Magazine, vi, 229.

t Neue. Schrcften der Hallis. naturf. Gesellschaft, i. 3.

:28

GENERAL ORISMOLOGY.

VI. — Affixion, Direction.

§ 43.

We have but few generalities to give upon affixion and direction,
insects having but few exterior organs, and those applied in a uniform
manner to the same place. But there are a few phenomena of greater
universality, which we shall now refer to.

§ 44.

Affixion is of a double kind. Adnate ( adnatum ) are those parts
which form an immediate continuation of the base upon which they
repose, and are besides immoveable. Articulate {articulatum) , are
those parts which stand in connexion with the body merely by a
flexible membranous medium, as sinews, &c., and possess a greater
or less degree of motion.

Processes such as Spines {spince, aculei ) ; Horns {cornua), or
plainly processes, forms, merely distinguished from each other by their
size, and often indifferently applied, require no general notice of their
affixion, it being precisely the same in all.

In the Articulation ( articulatio ), we distinguish the ball and socket
{Arthrodia), whereby motion is possible in every, or very many ways
(for example, between the head and prothorax), and the gyngiimous
(gynglimus) , which admits merely of the flexion and extension of the
two united parts.

§ 45.

With respect to the direction of parts, we distinguish —

Anterior ( aniicum ), lying near the head.

Posterior ( posticum ), that approximate to the end of the body.

Superior {supra), placed upon the back.

Inferior {infra), attached to the ventral portion of the body.

Both sides {ulrinque) , indicates a quality or peculiarity found on
each side of the body, and indeed at the same place.

Basal {basales), are parts or organs arising from the base of
another.

Terminal ( terminalis ), such as arise from its apex or end.

Axillary {axillares), are those which spring from the point of
union of two others.

GENERAL ORISMOLOGY.

Erect ( erectus ), a part which stands perpendicular upon another.

Aduncous {aduncus), a part which gradually bows from the direct
line.

Nutant {nutans), a perpendicular part, the apex of which bends
over.

Depressed ( depressus ), a part which appears to have been pressed
from above.

Compressed ( compressus ), on the contrary, when the pressure
seems to have been made from the sides.

Reflexed (reflexus, reclinatus ), when the margin of a part rises
upwards ; deflexed ( deflexus ), when it bends downwards.

Revolved ( revolutus ), and involved ( involutus ), are also thus
distinguished, but they indicate a greater degree of it — an absolute
rolling up.

Complicated (complicatus') , is a part laid longitudinally in folds ;
replicate {replicatus) , when the apex bends round, and the part is
thereby refolded.

A part prolonged or distended most considerably from front to back,
is called straight (rectus) ; when its greatest distension, however, is
at right angles with the length of the body, it is called transverse
(transversus).

Note. Many of the general terms of other writers, of Kirby, for
instance, are passed over, as their signification may be found in any
Latin dictionary.

THIRD CHAPTER.

PARTIAL ORISMOLOGY.

§ 46.

Having thus concluded the examination of the general differences
observed in all, or the majority of the organs, it now remains for us, as
the subject of the following chapter, to describe the insect body in its
separate periods of existence, and all the thence perceptible differences
of its various organs. The illustration of its several stages of develop-
ment first claims our attention.

§ 47.

Commencing our investigation with the first beginning of insects, we
may lay it down as a universal law, that all insects originate from eggs
(ova). With the exception of the few instances, wherein the egg is
hatched in the body of the mother, and the young thus born more fully
developed, a species of propagation to which the ancients applied the
name of Insecta ovo-vivipara ( Musca carnaria, & c.), all insects are
truly animalia ovipara. We must here indeed mention a second
exception, comprising those Diptera which are retained in the body
of the mother, until transformed into pupae, and are excluded in an
apparent egg-shell, but which is, in fact, the pupa-case. This species
of developement is peculiar to a single family, which has thence received
the name Diptera pupipara. Exclusive of these very rare anomalies,
we may observe four distinct periods of existence in every insect,
namely, those of the egg, the larva, the pupa, and the imago, or
perfect insect. In each of these states they are subject to manifold
differences, arising from the various groups to which they belong, and
to the contemplation of which we now pass.

PARTIAL OR IS MOLO GY.

I. — The Egg {Ovum).

§ 48.

The shape of the egg in the several classes of animals is in general
so exceedingly uniform, that a peculiar expression has been thence
deduced for its definition. Indeed, in the class of insects, the majority
of eggs are oval {ovale) ; but their shape is subject to so many differ-
ences, that it is necessary to enumerate the chief.

Perfectly globose {globosum) they are very frequently, particularly
in several families of Lepidopiera.

Semiglobose {semiglobosum), likewise in several Lepidopiera ; for
example, in Harpy a vinula (pi. i. f. 1).

Conic ( conicum ) also among Lepidoptera , as in Pontia Brassicce
(pi. i. f. 2)

Cylindrical {cylindricum), chiefly in such insects which lay them
in numbers, and close together ( Gastrophaga Neustria, pi. i. f. 3).

Lenticular {lenticular e), depressed, circular, and frequently
ribbed eggs, as in the moths (pi. i. f. 6).

Other forms are turban-shaped {tiaratum, pi. i. f. 11); melon-
shaped {cucurbilaceum) ; pear-shaped {pyriforme) ; barrel-
shaped (pi. i. f. 5).

Many eggs are placed upon long, straight {Hemer obius perla , pi. i.
f. 14), or shorter, bent {Ophion luteus, pi. i. f. 16), footstalks, and are
thence called petiolated {ova petiolata). Others have at one end par-
ticular appendages; for ex. the eared-eggs {ova aurita, pi. i. f. 17)
of Scatophaga putris , which, just before their apex, are furnished with
two short oblique appendages, that they may not sink too deep in the
matter whereon the insect deposits them ; or crowned {ova coronata ,
pi. i. f. 19) of the water scorpion {Nepa cinerea ), which are surrounded
at their superior extremity with a circle of strong spines, for the
reception of the following egg, whereby they hang in a row together,
and do not inaptly represent the small, short-limbed branches of the
horse-tailed grass {equisetum).

§ 49.

With respect to the surfaces of eggs, they are generally smooth
(o. glabra ), but also frequently uneven, or covered with a variety of
regular sculpture. Some are provided with lateral wings {ova alata ) ;

PARTIAL ORISMOLOGYc

others with short ribs extending from one pole to the other ( ova costata,
pi. i. f. 5); others ivith delicate filaments, which show the segments of the
embryo * ( Attacus paphia ). Other eggs display upon their surface
cross lines and sculpture, which gives them a reticulated appearance
{ova reticulata ), Hipparchia Hyper anthus (pi. i. f. 13) ; in others
these lines take a curve, so that the egg appears as if covered with
tiles {Hipp. Jurtina ) ; others, lastly, have decided knobs, making the
surface rough and uneven {Pont. Brassicce). We also occasionally
observe in eggs irregular wrinkles and impressions, but which do
not proceed from the sculpture of the superficies, and are accidental,
arising from their drying after being laid.

The colour of the eggs of insects is, notwithstanding their great
variety, not so variable as in the class of birds. White, yellow, and
green, are the chief colours, indeed almost the only ones ; for the few
others, as brown in Harp.vinula, or green {Cimex baccaru m), or banded
( Gastr . quercifolia , p. 1. f. 1), import but little, considering the greater
universality of the before-mentioned colours. We occasionally observe
very dark ones, even a black brown {Culex pipiens) .

§50.

It is also interesting to observe the way in which the eggs are
deposited.

Some lie solitary, and dispersed upon the plants and shrubs which
nourish the young {ova solitaria.') Others, which are deposited within
the substances, which serve the young as food, are called {ova imposita) ;
for ex. the eggs of the Ichneumons in the bodies of caterpillars. The eggs
of Gastr. neustria are placed in a spiral line around the young shoots of
the plant that feeds the caterpillar {ova spiraliter deposita, p. 1. f. 15) ;
others form irregular heaps, which the mother secures from cold, and
other prejudicial influences, by means of the hair of her body {ova pilosa,
p. 1. f. 4), for ex. Liparis chrysorrliea,fascelina , dispar ; others again
are concealed in lumps of dung {ova glebata , for ex. Gymnopl. pilula-
rius) ; others are formed in the galls of plants {gallce), occasioned by
the punctures of the mother {ova gallata, for ex. Cynips, Diplolepis ,
Trypeta) ; many, lastly, are placed in close cells formed by the parents
for this purpose {ova favosa , for ex. Apis , Vespa, Pelopceus ). All these
eggs adhere by a peculiar gummy secretion, and are thence called ova

* Lin. Tr. vii. 34.

THE LARVA.

gummosa ; but such eggs as lie dispersed in any substance, as, for ex.
the eggs of the house fly ( Musca dojnestica), in dung, are called naked
( ova nuda).

Besides those above indicated, there are many other differences, with
respect to their mode of being deposited, which, as they are peculiar
to certain genera or families, we can take notice of only in the natural
history of such groups.

II. The Larva. — ( Larva .)

§51.

As soon as the young insect breaks through the egg-shell, it is called
either larva, caterpillar, or maggot. In this state it frequently
appears in the shape of a long, more or less cylindrical, ringed worm,
either apparently without a head and feet, or having a head only,
or else provided with several (at least six) feet. In other, but less
numerous instances, the young assumes the form of the parent, although
necessarily much smaller, and always destitute of wings, whether the
parent insects possess them or not. Both kinds of metamorphosis thus
evidently differ considerably from each other from the mere form of the
young itself; and in the progress of their development this difference
becomes still more perceptible ; for whilst, in the latter instance, the
young one gradually attains both the size and perfect form of its
parents by a frequent change of skin only, in the former species of
development we observe, also after successive changes of skin, a state
of repose, in which the insect neither takes food nor, in the generality
of cases, moves — a period of its life distinguished by the name of Pupa
state ; and at the completion of this stage of its existence only, is it
that the perfect insect, or imago, bursts forth in all its beauty.

It was in reference to the actual differences of these modes of
development, that the names were applied which are used to distin-
guish them. Taken collectively, they are called metamorphoses ; the
application of which name may, doubtlessly, be justified by the decided
dissimilarity of the same individual insect in its several stages of exist-
ence. The last kind of metamorphosis is called complete ( metamorph .
completa ), because in it alone there is a true metamorphosis of the
individual ; the former, on the contrary, is called incomplete ( m .
incompleta ), since in it there is, properly speaking, no change of form,
but merely a repeated casting off of the exterior skin.

Although these terms are strictly derived from the condition of
change, other writers, Fabricius for instance, have had different views.

PARTIAL ORISMOLOGY.

The names he proposed for the, according to him, several kinds of
metamorphoses are the following: —

Complete ( m . complela) is, according to him, that species of
change wherein the larva is formed exactly like the perfect insect.
It is found only among such as are destitute of wings in their perfect
state (e. g. Pediculus, Cimex).

Semi-complete ( m . semi-completa), when the young resembles the
parent with respect to form, but is as yet deficient in the wings peculiar
to the latter.

Incomplete (m. incompleta ), when the young creeps from the egg
as a maggot, and the pupa has free, distinct limbs, although quiescent
(Hymenoptera, Coleopter a).

Obtected ( m . obtecta), is the change only distinguished from the
latter by the limbs, as well as the body, being enclosed in a hard
corneous case, upon which their form and position are strongly indicated
( Lepidoplera ).

Coarctate ( m . coarctata) he calls, lastly, that change wherein the
larva is a maggot without legs, and the pupa is enclosed within a round,
almost egg-shaped, corneous case, upon which there is not the least
indication of the parts of the perfect insect.

In opposition to this apparently very precise distinction of the
different kinds of metamorphoses, we may object that many cases occur
which will not admit of being arranged under any of those heads ; for
example, the larva of Xylophagus is without feet, and yet the limbs of
the perfect insect are perceptible upon the pupa case ; it is the same
with the genus Siratiomys ; and again, a footless maggot is trans-
formed into a pupa with free limbs, as in Ichneumon. Exclusive of
these considerations the idea of a complete change is most strictly appli-
cable to what Fabricius terms incomplete, and his most complete, on
the contrary, being evidently the most incomplete. It consequently
appears to us preferable to adopt but two chief kinds of metamorphoses,
as, as we have seen, between the several subdivisions, very many
connective and alternative conditions exist.

§ 52.

The larvae of insects with an imperfect metamorphosis, are to be
recognised in general by their want of wings and scutellum (§ 76)
with the exception of the few instances wherein the perfect insect has
no wings. In such cases certainty can be derived only from their relative
size in knonw species, as the larvae are invariably smaller than the

THE LARVA.

imago. In other respects, they wholly agree with their parents as
regards their conformation ; the same orismology consequently applies
to them as to the latter, and with which we shall become acquainted in
the description of the perfect insect.

§ 53.

All larvae with a perfect metamorphosis have a long, generally
cylindrical body, composed of thirteen more or less distinct rings or
segments *. Many, which have neither a distinct head, nor feet, are
called maggots (PL II. f. 1) ; in others the head is clearly distinguished,
but the feet are wanting (PL II. f. 3) ; others again, in addition to the
head, have six feet, which are placed upon the three first segments of
the body following the head — these are called larvje (PL II. f. 4. 6) ;
others, lastly which are called caterpillars ( Erucce ), possess, besides
the six horny legs of the three first segments, several membranous legs,
called prolegs, upon the ventral and anal segments (PL II. f. 5,

7-12).

The portions of the body of larvae, consequently, which chiefly merit
our attention are, the head, the body, with its various clothing, and
the legs.

The head (caput) always occupies the first of the thirteen seg-
ments of the body. In many cases it does not at all differ from the
other divisions of the body, and is, like them, covered with a soft skin,
and equally flexible and changeable in its form. This conformation

* With respect to the number of the segments, the text might create a little confusion ;

for Burmeister says, at § 57, in rather an obscure passage, as it does not clearly define
whether he includes or excludes the head, that it consists of twelve segments ; thus
contradicting what he has previously said above ; and Ratzeburg*, in a paper upon the
apodal larvae of the Hymenoptera, figures them generally as consisting of thirteen
segments, which is their true number, — the first and second of which become the head, the
third, fourth, and fifth, the thorax, the sixth the pedicle, seventh to thirteenth the abdo-
men ; but, at fig. 48, he represents the larva of Apis Mellifica with fourteen segments.
Whether this arise from his having figured the larva of the male of that insect, I do not
know, for the text does not elucidate it ; but the accompanying figure (44) appears to be
the pupa of the male, as it has seven segments to the abdomen. I am not aware that
it has been before observed, that the larva; of the males of the aculeate Hymenoptera
will necessarily have an additional segment. Ratzehurg seems to take great merit to himself
for having discovered that the larva of the Hymenoptera are headless, as he says, and
seems to insinuate a censure upon Swammerdam, Reaumur, De Geer, Kirby and Spence,
Latreille, &c., for not having noticed as much. It is evident that these writers considered
the two first segments as the head, and justly; for although as yet destitute of the usual
organs, they were in fact the head, only requiring further development Tr.

* Nov. Act. Med. Phys. Acad. Cses. Leop. Carol. Nat. Curios, t. VIII., pi. i. p. 145.

D 2

PARTIAL ORISMOLOGY.

of the head occurs only in the maggots, which are destitute of all the
organs observable in the heads of caterpillars, such as antennae, eyes,
&c. ; but there are to be seen, in the anterior opening which forms the
mouth, two horny bristles, which seem to represent the mandibles, which
serve for the destruction of its prey, when, for instance, the maggot
feeds upon other insects. In larvae and caterpillars, however, the
whole head is covered by a peculiar corneous case, which is divided into
two by a perpendicular suture descending from the vertex, and
separating in a fork just above the mouth. The general form of this
covering is more or less round, resembling a hemisphere ; in many
instances it has a triangular, and often a complete heart-shaped figure
( Sphinx Ligustri , Smerinthus Populi , and many others) ; sometimes
each half is produced at the vertex into a pyramidal process ( Apatura
Iris , PL II. f. 16), or the whole superior part of the head is completely
covered with thorns and spines ( Limenitis Amphinome , PI. II. f. 15).

As peculiar organs of the head of larvae, we must notice the oral
apparatus, the antennae, and the eyes. All true caterpillars have
mouths adapted to manducation, as have also all larvae with horny legs,
and, indeed, many without legs. The mouth is discoverable at the
anterior or inferior contracted portion of the head ; it is formed by the
fiat, longitudinally quadrate (sometimes taking the shape of a segment
of a circle) corneous upper-lip, or labrum ( labrum , PI. II. f. 13, d) ;
the equally strong corneous, horizontally-moving upper-jaws, or mandi-
bles ( mandibulae , PI. II. f. 13, ft, ft) ; the weaker, but very similar,
under-jaws, or maxillae ( maxilla , c, c ), with their feelers, or palpi
{palpi), and the likewise flat, more or less triangular, horny under-lip,
or labium ( labium , d ), which also is very generally furnished with
short feelers, or palpi; and this under-lip, or labium, closes the mouth
from below, as the labrum does from above, whilst the closed mandibles
completely shut the orifice in front. All these organs are also found
in the perfect insect, and we shall consequently describe them more in
detail when we arrive at that stage of its existence.

The antenna {antennae, f, f) are placed near the mouth, at the
base of the mandibles and maxillae. In larvae they consist of but few,
generally but three joints, or short narrow corneous cylinders, united
together by a delicate skin. They are always of a bristly or filiform
shape, even when the antennae of the perfect insect are very differently
constructed ; for in caterpillars they present themselves as very short
conical processes, while in the butterflies, which proceed from them,
the antennae are very long, and many-jointed.

THE LARVA.

Many larvae are destitute of eyes, namely, all maggots with an
undeveloped head, as well as many larvae with a distinct corneous
head-plate. The eyes of larvae are always simple, and perfectly agree
in form with those eyes of the perfect insect, with which we shall
become acquainted as ocelli. They are also placed in the vicinity of
the mouth, close behind the antennae (g, g) ; they vary in number
from one to six on each side ; but the caterpillars of butterflies appear
invariably to possess the latter number.

§ 54.

These, as well as the larvae of the saw-flies ( Tenthredonodea and
Urocerata ,) and those of the May-flies ( Phryganeodea ), possess,
attached to their maxillae, a peculiar organ, which Kirby and Spence
very aptly call a spinneret (fusulus, PL II. f. 14), which is of great
importance to them for the preparation of their cocoon. It originates
from the anterior portion of the labium, and is a slight tube, obliquely
truncated at its apex, and composed of several alternately corneous and
membranous slips. It is through this tube that the clammy liquid
passes, which has been secreted by two glandular organs for the pre-
paration of the silk, and which can be spun into thicker or thinner
filaments at the will of the caterpillar, by the power it possesses
of distending or contracting the cavity of the tube. The larvae of
some Coleoptera and Dictyotoptera, which also spin cocoons, do not,
however, possess this organ ; but the silk is produced by an apparatus
at the anus: a very different construction must consequently obtain
in them. »

§ 55.

The head is immediately succeeded by three segments, which ulti-
mately, in the perfect insect, form the thorax. They are recognised in
many larvae by the short, corneous, articulated and conical feet, which
are observed only upon these segments. In general they are con-
structed like the rest ; but in the larvae of many Coleoptera , particularly
of the superior families, they are distinguished by a peculiar conforma-
tion : their exterior integument is corneous, like that of the head, whilst
that of the abdomen is enclosed by a soft skin. Among the case or
caddis-worms also ( Phycis , Phryganea'), which, as larvae, dwell in a
case made by themselves of sand and bits of stick, and wherein also
they transform themselves into pupa, a similar construction is percep-
tible (pi. III. f. 1).

§ 56.

The legs ( pedes ) of larvae take a different form, according to their
position

PARTIAL ORISMOLOGY.

The true legs, thoracic legs ( pedes merely, or pedes vert, PI. II.
f. 17), are affixed to the three first segments of the abdomen, and con-
sist of several joints, like those of the perfect insect. Each of these
joints is inclosed in its peculiar corneous cylinder ; and it is only where
these joints are connected, that a flexible membrane completes their
union. By means of this arrangement we are enabled distinctly to
recognise the joints analogous to those of the perfect insect, so that the
leg of a caterpillar may be considered, as truly as that of the butterfly,
to consist of the hip {coxa), trochanter ( trochanter ), thigh (t femur ),
shank (tibia), and foot {tarsus). It is, indeed, true that these joints,
particularly in caterpillars, follow so closely upon each other, from their
shortness, that the whole leg has the appearance of a small conical
process ; but in many other orders, for example, in the larvae of the
Carabodea, the individual joints closely approach in form to those of
the perfect beetle.

In general, all larvae provided with legs possess the true legs, or
thoracic legs ; indeed, in most of the larvae of the Coleoptera and
Dictyotoptera, these alone are to be found.

The ventral and anal legs, or prolegs ( propedes , pedes spurii,
PI. II. f. 18), are short, thick, muscular, unarticulated processes upon
the ventral and anal segments of many larvae ; they are exclusively
peculiar to this second stage of existence, and entirely disappear upon
its transition to the pupa state. In form, they are sometimes short
cones, with an obtuse apex ; sometimes longer thin pedicles, distended
at their extremity into a flat sole ( planta ) ; sometimes indistinct, very
moveable knobs or tubercles, which are protruded or withdrawn at the
will of the larva. In these cases, the sole is very generally either half
or entirely surrounded by a double or single row of short claws, or
crotchets, by the aid of which the caterpillar is enabled to attach itself
firmly in climbing ; the tubercles, on the contrary, are mostly unpro-
vided with them ; and, indeed, many of the prolegs of the first adduced
form do not possess these claws. In many, particularly those whose
sole is much distended, it is clapper-shaped, that is to say, composed
of an exterior and interior flap, which move in opposition to each
other like a pair of tongs, and thus form a claw. Kirby and Spence
have constructed a tabular division of larvae from these differences,
which we shall here introduce for the purpose of giving a general view
of them.

I. Larvae without feet.

1. With a membranaceous head of indeterminate shape {Dip-
tera, PI. II. f. 1).

THE LARVA.

2. With a corneous head of determinate shape, (many Coleo -
ptera, the Rhynchophora , many Hymenoptera , Culicina,
Tipularia), PI. II. f. 3.

II. Larvae with feet.

1. With legs only, and with or without an anal proleg.

a. Joints short and conical ( Elaterodecij Cerambycina),

PI. II. f. 4.

b . Joints longer ( Cicindelacea , Carabodea , Hydrocan-

tharides, Brachypiera, Lamellicornia , Coccinellacea,
Neuroptera), PI. II. f. 6.

2. Prolegs only ( Tipularia , and other Diptera, QLcophora ),

PI. II. f. 2.

3. Both legs and prolegs ( Lepidoptera , Tenthredonodea ).

a. Without claws ( Tenthredonodea ), PI. II. f. 5 and 7-

b. With claws ( Lepidoptera ), PI. II. f. 9 and 11*.
Prolegs, in some instances, occur upon all the segments of the

abdomen, and even upon the thoracic segments there are found legs
resembling the prolegs in form, in those cases where true thoracic legs
are wanting (Rhynchophora) . But in the majority of cases, the first
abdominal segment, or fourth segment of the body, has no prolegs,
but they are sometimes observable upon this segment ((Ecophora

* Burmeister, in this table, does not exactly follow that given in the Introduction to
Entomology, vol. iii. p. 144. But why, after quoting it as that of Kirby and Spence, he
should make alterations in it, it is difficult to say, particularly as these alterations are not
material. But he refers to the German translation of their work; and, from not knowing
that book, I am unable to determine how far it was the cause of the difference : hut, to do
justice to these authors, I give the table in their own words : —

I. Larvae without legs.

i. With a corneous head of determinate shape (coleopterous and liymenopterous

Apods — Culicidce , som dTipulariae, &c. amongst the Diptera).

ii. With a membranaceous head of indeterminate shape ( Muscidee , Syrphidce ,

and other Diptera).

II. Larvae with legs.

i. With legs only, and with or without an anal proleg (. Neuroptera , and many

Coleoptera).

1. Joints short and conical ( Elater , Cerambycidce , &c.).

2. Joints long and subfiliform ( Staphylinus , Coccinella , Cicindela , &c.).

ii. Prolegs only (many Tipularia, and some subcutaneous lepidopterous larvae,

&c.).

iii. Both legs and prolegs ( Lepidoptera , S er riper a, and some Coleoptera).

1. Without claws (S er riper a, &c.).

2. With claws ( Lepidoptera , &c.). — Tr.

PARTIAL G RI SM OL OG Y.

Rajella *), and in the rat-tailed maggot (the larva of Eristalis tenax ),
which has no thoracic legs, but only prolegs upon the segments of its
body. The following table presents an arrangement of larvae, grouped
according to the position of their prolegs.

1. Prolegs upon all the segments of the abdomen except the first
(eight pairs).

The genus Cimbex, PI. II. f.7-

2. Prolegs upon all the ventral segments, excepting the first and
penultimate (seven pairs).

The genus Tenthredo.

3. Prolegs are wanting upon the first, antepenultimate, and penul-
timate segments (six pairs).

The genus Hylotoma, PI. II. f. 5.

4. Prolegs upon the anal and four ventral segments, viz. the sixth,
seventh, eighth, and ninth, PI. II. f.9.

The majority of caterpillars, namely all the hawk moths ( Sphing -
odea), butterflies ( ' Papilionacea ), bombyces {Bomby coded), as well
as the majority of owlets ( Noctuacea ).

5. Prolegs upon the anal, and three ventral segments, viz.

a. The sixth, seventh, and eighth.

The caterpillars of many owlets.

b. Upon the seventh, eighth, and ninth.

Many caterpillars of the Pyralodea, Hypenarostralis.

6. Prolegs upon the anal and two ventral segments {Larvae
geometriformes), PI. II. f. 10.

The genera Plusia, Ophuisa, Acontia, Metrocampus , Lat. ;
Ellopia, Tr.

7- Prolegs upon the anal, and one ventral segment (the last but
three). Larvae geometrce, PI. II. f. 11.

The majority of the Phalaenodea.

8. Prolegs upon the anal segment only.

Some moths ( Tineodea ), the genus Lyda , and many coleopterous
larvae.

9. No prolegs upon the anal segment, but upon four of the ventral
segments (the seventh to the ninth), PL II. f. 12f.

The larvae of many moths (for ex. Harpy a, Platypteryx).

* Naturforsch. St. IV. p. 37, &c.

■f This is a similar arrangement to that of Reaumur, in his second Memoir in the first
volume, only somewhat modified and enlarged. — Tr.

THE LARVA.

Besides these, the larvae of several Diptera have been described by
different writers, as having, some, prolegs upon all their segments,
and others only upon their first and last. Much irregularity appears to
prevail in this Order with respect to the feet of the larvae, which
is clearly evinced from the descriptions of those of the different
families of the Order. The preceding sketch of their distribution
must, consequently, suffice for the present, until we proceed to
their detailed description. A precise, and, at the same time, natural
division of them, is scarcely possible, from their multitudinous differ-
ences ; but what we have remarked above, we hope will serve, in
some measure, as a guide.

§57.

We now proceed to the consideration of what still remains to be
observed upon the construction of the body of the larvae.

It has already been remarked, that it properly consists of twelve
segments, which are separated from each other by slight constrictions.
Beyond this, there are but few generalities to notice in it. For the
most part, each of the segments, with the exception of the second, third,
and last, has, on each side, a small longitudinal aperture, which is
surrounded by a broad callous margin, and is called spiracle, or
stigma ( spiracula , stigma), and by means of it the air is accessible to
the respiratory organs distributed throughout the body. Many of the
larvae which live in water, have, instead of spiracles, membranous
laminae, or plates, throughput which the tracheae, or air tubes, are
distributed, and which thus supply the function of gills, and may,
therefore, be very properly called gill plates ( branchiae , — aeriductus ,
of Kirby and Spence). They are distinctly observable in the larvae
of many May-flies ( Ephemerae Phryganea). A similar respiratory
apparatus is observable in the larvae of many Diptera, although seated
at a different part. Some bear, like the larva of Stratiomys and gnats
(CWe<r), a coronet of a plumose form at their anus, by means of which
they more easily sustain themselves at the surface of the water. In the
middle of this coronet, or close to very similar appendages, are found
the orifices of the tracheae (compare the larva of Dytiscus ) ; in others
( Eristalis , PI. II. f.8) a pair of thin tracheae run parallely the whole
length of the body, and their orifice remains at the surface of the
water, while the larvae themselves repose at the bottom of the puddles
and pools.

PARTIAL ORISMOLOGY.

§ 58.

Different from these peculiar appendages, which we may
consistently consider as particular organs, is the spinose and hairy
clothing of the majority of caterpillars. We may, indeed, admit
that the majority of larvae are quite naked ; but this assertion
does not admit of extension to the order of the Lepidoptera, for very
many caterpillars move about enveloped in fur. The spinose cater-
pillars ( larvce aculeatce), are almost peculiar to the butterflies ( Papi -
lionacea ), but the larvae also of the tortoise beetles ( Cassida ), are
armed nearly all over with longer or shorter spines, but particularly
so upon the abdomen. In some we observe, upon each segment, four,
five, six, seven, or eight simple, and indeed, not unfrequently, branched
spines ( Vanessa polychloros), which gives the creature a wild and
forbidding appearance, and which may contribute much to the fear
with which the common man in general views these innocent and
harmless caterpillars. Much more terror is frequently evinced at the
indeed larger, but quite naked caterpillars, of the hawk -moths, which
are furnished, upon their last segment, with a straight or bent horn
(Sphingodea, larvce cornutce ), of which it is fabled1 that it supplies
the place of a poisonous and severely wounding sting. A few have,
instead of this, a furcate process (Harpy a, Ochs, Cerura ), the branches
of which are pierced, so that the caterpillar possesses the faculty
of protruding slender threads through these tubes, for the purpose, as
is supposed, of scaring inimical ichneumons (Larvce furciferce). But,
with respect to their powers of injury, greater attention is claimed by
the hirsute caterpillars ( Larvce ur since), which are completely
clothed with long hairs and bristles, and which, from their stiffness
and sharp points, will often cause an unpleasant inflammation upon a
delicate skin ; for, when rudely seized, the handling will cause it to
lose its dense hair, which, by piercing the skin, causes an itching
sensation, that induces the wounded person to rub the spot, and
thereby produces a swelling.

To go into greater detail upon the forms of larvse, appears
unnecessary, as, in the natural history of each Order, a characteristic
arrangement of their larvae will be at the same time given, and to
which we therefore refer.

THE PUPA-

III. — The Pupa State.

§ 59.

We have now arrived at the third and last stage of development,
viz., the PUPA STATE.

The pupae of insects, with an incomplete metamorphosis, perfectly
agree with their larvae in form and structure ; but those whose imago
is provided with wings, have, at this period of their existence, the
rudiments of these organs, as an evident mark of distinction. They
may, accordingly, be distributed into two divisions —

1. Pupae without alary appendages, which, according to the Fabrician
definition of the metamorphoses, must be called complete pup^e, but
which, according to us, are necessarily incomplete pupae. To these
belong the lice ( Pediculus ), the bed bugs ( Cimeat lectularius) , many
species of the genus Phasma *, and some other wingless Hemiptera
and Orthoptera.

2. Pupae with* the rudiments of wings, according to the former
definition. Semi -complete Pupce, but by us they are called Sub-
incomplete. These comprise all the pupae of the winged genera of the
Orders, Hemiptera , Dictyotoptera, and Orthoptera.

Lamarck calls nymplice all pupae with an incomplete metamorphosis.

§ 60.

In insects with a complete metamorphosis, the pupa state is a
very peculiar and characteristic period of their existence. Exteriorly
a perfect stand-still appears in the process of development, for the
pupa, in the majority of cases, is quiescent, and does not take the
least nourishment to itself ; but, internally, the greater changes are in
progress. In a subsequent division of this work, we shall treat in
detail of these changes, for we must restrict ourselves here to the con-
sideration of the exterior form alone of these pupae. We divide them
into the two following groups.

* Or rather of the family Phasmidce. They are all contained in the sub-family
Apterophasmina , which comprises twelve genera in Mr. G. It. Gray’s valuable “ Synopsis
of the Species of Insects belonging to the family of Phasmidse,” just published by Longman
and Co., and to which we call the attention of Entomologists, as containing an elaborate
distribution of all the known species of this singular and interesting tribe. — Tr.

PARTIAL ORISMOLOGY.

I. Pupae which freely lie, hang, or are in any way fastened or
attached in their particular element, naked pup^e ( Pupae nudce).
This mode of change is not particular to any individual Order, but it
occurs, as well as the following, throughout all the Orders.

II. Pupae which repose in cases artificially prepared by the larvae ;
incased puPiE ( Pupa follicutatce) , which case is called cocoon
( incunabulum , folliculus ) .

But these differences do not at all apply to the shape of the pupa
itself. The following are the terms thence given by former writers.

Coarctate and obtected pupae ( Pupa obtecfa, coarctata ), are
those which are inclosed in a firm, egg-shaped, corneas case, and which
do not in the least indicate the parts of the perfect insect (PI. II. f. 21 ).
This transformation is peculiar to many families of flies ( Syrphodea ,
( Estracea , Muscaria). The surrounding case is the dried skin of the
larva, and, strictly considered, it is analogous to the cases of many
insects with a pupa folliculata — for the true pupa, with its clearly
distinguishable limbs, lies inclosed beneath this case. This kind of
pupa is probably peculiar to all such insects whose larvae do not moult.

Masked pupas ( pupa larvata), are those whose general inclosure
is likewise a horny case, but upon which the different parts of the
future insect are traced in lines (PI. II. f. 19). Lamarck calls both these
kinds of pupae chrysalis, the former chry. dolioloides, the latter chry.
signata ( Lepidoptera , many Diptera).

Exarate or sculptured pupae ( pupa exarata), are such in which
the limbs of the perfect insect are observed to lie free, although still
closely attached to the body (PL II. f. 24). TheseLamarck calls mumia,
and particularly mumia coarctala ( Coleoptern , Hymenoptera), whilst
the pupae of the Phryganea, which, in the last stage of their pupa
existence possess some degree of motion, he calls mumia pseudo-
tiympha.

A naked pupa is called subterraneous ( pupa subterranea),
when, during this period of its life, it lies buried in damp earth.
But if it hangs perpendicularly with its head downwards, as in many
butterflies ( Hipparchia Egeria ), PI. II f. 20, it is called an adherent
pupa ( pupa adharens), but if placed upright against a vertical object,
and supported by a delicate filament passed transversely across its
thorax (PI. II. f. 26), it is called a bound pupa. This kind is also only
found among the butterflies ( Poutia Cratagi). An incased pupa,
whose cocoon remains partially open ( Salurnia , Phryganea), is usually
called a guarded pupa {pupa custodiata).

THE PUPA.

§ 61.

With respect to the construction of the body of the pupa, we find
much more distinctly in it, than in that of the larva, the indication of
the division of the body into three chief parts, the head, thorax and
abdomen. This division of the body is shown by a constriction in the
pupa case, as we observed, also, to be in the larva. If we, with Kirby
and Spence, perhaps not quite appropriately, call this exterior sheath
the case (theca) of the pupa, we may then divide it into the following
parts, from its now more distinctly apparent exterior organs.

Head-case (cephalotheca) is the anterior hemispherical division,
which incloses the head of the future perfect insect. In it we must again
distinguish the eye-case (opthalmotheca), the mouth-case (stoma-
totheca), which, in the Coleoptera , incloses the mandibles and palpi ;
or, as in many Lepidoptera, covers the protruding proboscis ; and, in
this latter case, is called by Kirby and Spence tongue-case (glosso-
theca). In front of the mouth-case lie the leg-cases (podothecce),
inclined towards each other at acute angles ; very near to them, but
directed outwards towards the back, the either long, pointed, or shorter
thicker antenisle cases (Ceratothecce)% . Next to the head-case
follows the trunk-case (thoracotheca, — cytotheca of Kirby and
Spence), which is covered below by the wing-cases ( pterothecee ), which
originating at its sides, embrace it in the direction of the abdomen. The
form of the trunk-case is influenced by the different conformations
of the thorax in the several orders, so that the three segments of the
thorax are sometimes more distinctly discriminated ; and, when so
we may apply the terms prothoracic-case ( prothoracotheca ),
mesothoracic-case (mesoihoracotheca) , and metathoracic-case
(metathoracotheca), (Coleoptera and Hymenoptera) ; but sometimes,
from the preponderating size of the middle portion, we observe all
the three divisions unite in one (. Diptera , Lepidoptera). Immedi-
ately upon the trunk-case follows the abdomen-case (g aster oiheca) ,
which consists of nine (more or less) distinctly separated segments;
and at its apex we observe the future anal orifice indicated ; and on
both sides of each segment the easily recognisable spiracles (stigmce,
spiracülce) are perceptible.

The apex of the last segment (apex abdominis , — cremaster of Kirby
and Spence) it is still important to notice, from its truly innumerable
differences. Very generally it terminates in a conical, either acute or

* Not CeratheccB , according to Kirby and Spence.

PARTIAL ORISMOLOGY.

obtuse process ( Sph . ligustri), or there are two close together ( Noct .
amethystina) , which sometimes, as in Hydroph-piceus, Noct. lucipara,
hang downwards as long bent hooks. Sometimes we observe many
little crotchets or points ; and, also, as in Harpya Fagi, an indented
pectinated process (P. II. f. 25, and other forms in f. 22 and 23).

If the abdomen terminate in a protruding ovipositor (Sire#, Pimpla ,
Cryptus ), this, also, has its peculiar case ( acidotheca ) ; which, when
the ovipositor is short, stands forth free ( Sirex ); but when much
longer, as in Pimpla , it is turned round upon the venter, or the back
of the pupa.

§ 62.

The superficies of pupae is still more generally naked than that of
larvae. But few instances have been hitherto observed, in which they
are covered with isolated bristles (Hydroph. piceus), or fasciculate
(several Bombyces, for example, Orgyia pudibunda, Pygera buce-
phala *), or covered with wreaths of hair. The processes, and angular
or produced parts of the pupa itself, which arise from the form of the
included insect, must be clearly distinguished from such clothing. With
these processes may be classed the already described apical spines, and
the also before indicated protruding proboscis of many Lepidoptera
(glossotheca). In the hawk moths ( Sphinx Convolvuli , Ligustri), it
presents itself in an obtuse club, bent towards the body between the
two first pair of legs ; in the owlets ( Cucullia Tanaceti, Plusia con-
sona, and others of these genera), it protrudes as a clavate process
beyond the legs, and then lies free opposite the first ventral segments
of the abdomen. The tracheae, also, of many dipterous pupae which
live in water, for example, of the gnats (Culex), in which they project
from the sides of the thorax as two clavate processes, well deserve to be
mentioned here.

Shorter processes, such as spines and wrinkles, arise from several
portions of the body of the pupa, and exclusively belong to its case.
Thus the pupa of the stag-beetle (Lucanus cervus) has, upon the sides
of its first abdominal segment, several spines united in a bundle,
resembling those of the Hydroph. piceus , in front of its thorax, or the
pupa of an Asilus, figured by De Geer, with spines upon its head, and
abdominal segments f . The pupa of the goat moth ( Cossus ligniperda)

* Burmeister has evidently made a mistake here ; for the pupa of Pygera bucephala
is perfectly smooth The pupa of Leucoma Salicis would have been a better example. — Tr.

•f* Memoirs, 76, pi. 14, fig. 8.

THE PUPA.

has, upon the sides of each abdominal segment, a row of slight crotchets,
as have, also, many other lepidopterous pupae ; in many they present
themselves as elevated, somewhat notched, or indented stripes ( admi -
nicula of Kirby and Spence).

§ 63.

Many pupae have other protuberances, which, from their shortness and
thickness, can neither be considered as processes nor as spines, but are
merely prominent angles, which equally proceed from the form of the
inclosed insect, and are exclusively peculiar to the pupae of some Lepi-
doptera , and Diptera. These forms are found only among the butter-
flies of the former order ; of which they are, however, the characteristics
of the majority. In general, two conical processes rise in front of the
eyes ; these appear to enclose the palpi of the butterfly, and are then
called palpi-cases ( pselaphothecce ) ; then the trunk-case expands in
several lateral angles ; but chief of all is the process upon the back, in
the form of a long pyramid, or resembling a man’s nose, so much so,
that a pupa of this description, upon the first glimpse of it, looks like a
human face, particularly when, as is often the case, there are dark
spots within the impressions above the pyramid, which, consequently,
have all the appearance of eyes. Pupae, thus formed, are called angular
(p. angulares) ; the rest, in contradistinction, are styled conical
(p. conicce).

§ 64.

Before we conclude our consideration of the pupae, we will add a
few words upon their different colours.

All pupae which are placed in shady, dark situations ; for example,
in the earth, or in water, or in perfectly obscure dwellings (as the
obtected pupae) are of a yellowish white, but which become darker
upon exposure to the light ; the rest, particularly the pupae of the
nocturnal and crepuscular Lepidoptera , and of the minute moths, &c.
are of a bright brown when their place of concealment is within the
earth, but they are darker when they are inclosed in transparent webs#
The majority of the pupae of the diurnal Lepidoptera have a greenish,
or yellowish grey brown colour, many are speckled ( Pontia Cratoegi ),
others have large spots of a glittering gold colour upon the thorax and
abdomen, and they alone thence obtain the name of chrysalis , aureliaj
which names have Been applied in general, but chiefly by early writers,
to the pupae of all the butterflies.

PARTIAL ORISMOLOGY.

IV, — The Insect in its perfect State (Imago).

§ 65.

An insect, when it quits its pupa case, is called perfect (imago,
insectum declaratum, perfectum). Upon observing it more closely,
we immediately detect several divisions of the body, which have
become now more distinctly separated than they were in the earlier
stages of its existence. Henceforward we always observe three chief
divisions, which are called head (caput), thorax (thorax), and
abdomen (abdomen). We will now take these parts consecutively,
but prievously insert an observation or two upon the name of these
creatures.

It is from this division of the insect body that the various names
which have been applied by naturalists for the designation of the
class, are deduced. Aristotle, the most ancient of all, called insects
5/E vrojia, which word is derived from evre^veLv, to cut in. His
name, therefore, very evidently refers to the divided body' of these
creatures. The Roman writers followed the example of this great
man, and called our favourites Insecta, derived from insecare, which
likewise signifies, to cut in. This name was adopted by all authors, and
Linne introduced it among the systematic names of animals, whence it
has passed into almost all the; living languages. The Germans have
also long used the word, insect ; but Oken, latterly, when he sketched
his German nomenclature for all natural bodies, called insects Kerfe . a
word which has doubtlessly the same signification, he having derived it
as we surmise, we conceive correctly, from Kerben, to notch, or indent.
Other German writers, as Carus, Wagler, Burmeister, &c. have adopted
Oken’s term, as having in fact the great merit of being of genuine
German extraction, and which at the same time equally well preserves
the advantage of a designation expressive of the predominant character
of the class.*

* We retain this latter paragraph, which has rather a German than an English interest,
in deference to the opinion of a very distinguished man. But it may be of use, from the
German language having now become so prevalent and important a study, to explain a
term which has not yet found its way into the dictionaries, and which, possibly, every
writer may not think it necessary to illustrate when employing it. — Tr.

THE HEAD.

I. — The Head (Caput).

§ 66.

The Head*, the first of the three divisions of the insect body,
displays considerable variety in its form. In general it approaches to
the globose, or semi-globose, and is surrounded by a plain corneous
case, and contains the different organs of the senses. From its sim-
plicity, it is evident that we cannot so readily distinguish by peculiar
terms particular divisions in it, as we can certain regions, and these
must agree with the analogous portions of the head of the higher
animals.

With respect to the most usual forms of the head, modifications
of the globose seem to prevail, with the occasional predominance of
either its longitudinal or transverse diameter. Thence proceed the
egg-shaped, longitudinal, obtuse-triangular, heart-shaped forms, &c.,
which we meet with in so many groups of insects. It is very fre-
quently produced into notches and prominences which are called horns
( cornua ) ; these are always integral portions of the corneous case, and
are never articulated and moveable.

§ 67.

The following are the portions of the head most usual to note.

We must first distinguish the true skull ( cranium , calva according
to others), and thence proceed to the generally moveable organs
attached to it ; it therefore comprises the whole of the head, excluding
the antennae, eyes, and oral apparatus. If we wish to notice the upper
part, from the front across the vertex to the posterior cavity, we call
it upper-head, skull-cap (< calva , epicranium , Strausf), PI- III.
f. 11, A. It is limited in front by the clypeus ( clypeus ), called lower
face ( [hypostoma , in the Diptera by Meigen and Bouche, the epistomis
of Latreille), or that portion which lies above the organs of the mouth ;
it is bordered laterally by the sides of the head, and extends as far as

* In explanation of our occasionally differing from other writers in the nomenclature
of the parts of the insect body, we refer to what we have said at § 9, II. and the note.

■f Considerations Generales sur 1’ Anatomie comparee des Animaux articules. Par
Here. Straus-Diirckheim. Paris, 1828. 4to. av. 10 fig. (p. 52, &c).

PARTIAL ORISMOLOGY.

the eyes (PI. III. f. 11, c). Kirby and Spence call this part the nose
( nasus ), and distinguish the anterior part as rhinarium, and the more
lateral ones as post-nasus ; certainly without foundation, for although
many naturalists have supposed the organs of smell to exist here,
none have yet been able to prove they do so, and we must therefore
decidedly reject a name founded upon such a supposition. The front,
forehead, or brow ( frons ), is that portion which intervenes between
the posterior margin of the clypeus between the eyes, to where the
head commences tobe flattened above (PL III. f. 11, b). Nitzsch distin-
guishes that portion of it which lies between the eyes as middle head
(sinciput). Vertex (vertex) is the upper flattened portion of the
head upon wdiich very generally the simple eyes or ocelli ( ocelli ) are
found (PI. III. f. 11, a). In many insects, particularly Coleoptera, the
vertex is not apparent, as they bear their head withdrawn into the
thorax. Face ( facies ) is the anterior portion of the head above the
mouth, and includes the clypeus, the front, and the parts bordering
upon the eyes. It is chiefly from the front and the vertex that the
above-mentioned prominences originate, called horns (cornua), from
their frequently not inapt resemblance to the horns of the ruminants.
These parts are often covered with hair, which is then called head
hair (capilli) ; a fringe of hair seated upon the clypeus, over the
mouth, is called whisker (; mystax ), and is found chiefly among the
Dipt er a in the families of the flies of prey (Asilica) and the true
flies (Muscaria).

The lower part of the head is divided into the following portions.

The gula ( gula , PI. III. f. 12, d), or throat (jugulum) extends,
according to Kirby and Spence, from the anterior portion, where the
chin (see below, § 68) is attached, or from the orifice of the mouth in
general to the commencement of the neck, and comprises consequently
the whole middle portion of the lower head, and which Straus calls,
from its being the support of the whole, the basal part ( basilaire , pars
basalis). In many of the Coleoptera, for example in Geotrupes nasi-
cornis , it is produced into a smooth boss ; in other instances (Cardbus),
this part is sloped, and its anterior raised fnargin, to which the chin is
attached, is swollen into a thick callosity (PI. III. f. 12 and 13, d.).
When it assumes this form, some entomologists are inclined to call it,
but very injudiciously (consult § 9, ii. and note) head-breast -bone
(sternum capitale). Straus correctly considers this swelling as
belonging to the basal part, and which he calls prebasal part (pre-
basilaire).

THE HEAD»

The sides of the head, from the eyes downwards to the mouth, are
called cheeks {gence, PI. III. f. 14, e), particularly when they consi-
siderably protrude, as in some of the Diptera (Myopa). We again
distinguish in them the anterior portion, extending as far as the
articulation of the mandibles and maxillae, or the commencement of
the mouth, by the name of reins or lora ( lora , PI. III. f. 13, e), and
the posterior portion lying proximate to the eyes, as the temples
{temp or a, PI. III. f. 13, f).

The back of the head around the commencement of the neck is the
occiput ( occiput , PI. III. f. 12 — 14, g). In many instances, chiefly
among the Coleoptera and Orthoptera, in which the longitudinally
formed head is deeply withdrawn within the thorax, this portion is not
at all visible, but it is prominently perceptible in the Diptera and
Hymenoptera, which carry their heads free. The aperture behind the
head, through which the internal organs are continued, is called the
occipital foramen (foramen occipitale).

In many insects the commencement of the neck is likewise an inte-
gral portion of the head. The neck ( collum ) is that part which unites
the head with the thorax. In the majority it is merely a membranous
tube, and it is among a few of the Coleoptera only {Staphylinus, Leptura)
that the back of the head is constructed into a short corneous cylinder,
to which the membrane of the neck is attached. Some entomologists
call this part the collar ( collare ), a name which is applied by
others (for example. Klug, Kirby and Spence,) to the prothorax of the
Hymenoptera.

The Mouth (Os).

§ 68.

From this consideration of the different parts of the head we pass on
to the investigation of the several organs attached to it. These are the
parts of the mouth, the antenna, and the eyes.

Tlie oral organs, or parts of the mouth ( partes oris, instrumenta
cibaria, trophi) lie at the anterior, or inferior part of the head, and
surround the mouth (os). When attached to a long corneous and
generally cylindrical prolongation of the head, this part is called the
snout or rostrum ( rostrum ), which, however, must be well distin-
guished from the proboscidal prolongation of the oral organs them-
selves ; the rostrum being merely a continuation of the corneous cover-
ing of the head, and not a distinct organ.

e 2

PARTIAL ORISMOLOGY.

The exact description and knowledge of the oral organs is of great
importance in Systematic Entomology, as these parts supply the charac-
ters of many genera, and not rarely of entire families: we must, con-
sequently, here give a very precise definition of their forms.

In the first place we must distinguish the biting organs ( instr . cib.
mordentia , s. libera ) from the sucking ones (instr. cib. suctoria ) ;
and the former are also specially called masticating organs (instr.
masticandi) ; these stand freely beside each other, and display much
uniformity in their structure as well as great regularity of shape * * * §,
whereby they announce a superior degree of development, so much so,
that insects with a masticating mouth, notwithstanding its very
similar conformation, take the precedence of those with suctorial organs.
The latter are more or less united together, and assume very different
shapes in the several orders, of which we shall particularly treat below-

The masticating mouth (as found in the Coleoptera , Dictyotoptera ,
Neuroptera, and many Hymenoptera) consists of the following organs : —

The upper lip, labrum, ( labrum , labium superius , PI. III. f. 11. i),
is very generally of the form of a segment of the circle, or a triangular,
or quadrangular, somewhat convex corneous plate, which is united
posteriorly by a membranous hinge with the clypeus. Fabricius f
originally called this organ clypeus, in which he was followed by Illi-
ger J. This latter writer applied the name of labrum to the narrow
anterior appendage of the true labrum, which is very seldom present,
but is found in some of the Hymenoptera (Hylceus §), and is called by
Kirby and Spence the appendicle (appendicula) .

The upper jaws or mandibles (mandibulce, PI. III. f. 11 — 13. o, o),
which are two strong, corneous, somewhat bent hooks, their inner
margin being more or less dentate ; and which articulate with the
cheeks at their broad basis, and move by ginglymus, opposed to each
other like the blades of scissors.

The under jaws or maxilla (maxillae, PI. III. f. 12 and 13, p, p),
are also a pair of organs which in many respects resemble the mandibles,
although smaller and more delicately constructed. They are not simple,
but distinctly consist of four pieces. The two first hang attached to

* See what Kirby and Spence say upon their variety, Introduction to Entomology,

vol. iii. p. 473 ; what Burmeister says above must be taken comparatively — Tr.

-j- Philosoph. Entom., p. 37. X Terminologie, p. 220.

§ Burmeister says it is the genus Hylceus , without indicating that he means of Fabricius.
I know it only in the females of the genus Halictus, which are comprised in the above
genus of Fabricius Tr.

THE HEAD.

each other as well as to the head and labium by means of soft liga-
ments; the lowest, the hinge, ( cardo , PI. III. f. 16 and 17, 1, 1, or
the base, pars basalts ; — according to Straus, brauche transversale ,)
is narrow, thin and transverse, and articulates with the throat, forming
a right angle with the one that follows it, which is the stalk ( stipes ,
piece dorsale of Straus, 2, 2 of the same figure), and is thicker, stronger,
and larger, and above somewhat horny, but beneath softer and mem-
branaceous. Closely attached to this is the third piece, which is a
corneous scale, at the anterior margin of which the palpus is inserted
(thence called squame palpifere, by Straus), and which forms beneath
the case or covering of the maxilla. The fourth piece (the same plate
and figure, 4, 4) borders upon the two preceding, and is completely
horny, hooked, its interior margin concave, or, as well as the stalk,
covered with short stiff bristles. It is called the maxillary lobe
{lobus maxillce , — intermaxillaire of Straus), from its more generally
taking the appearance of a superior appendage of the stalk. In many
insects, particularly the Hymenoptera and coprophagous Petalocera
among the beetles (for example, Copris, Aphodius), it is a simple,
variously formed, flat, coriaceous scale, with its margin beset with short
hair ; in others, as among the Capricorn beetles {Lamia, Cerambyx) ,
it is thicker, and more solid and compact, and is divided into a harder,
internal {lobus internus ), and more membranaceous, external
lobe {lobus externus). This exterior lobe is the same organ which in
the Orthoptera covers the internal lobe like a cap, and then takes the
name of helmet {galea — PI. III. f. 17, 5 of Cychrus , PI. IV. f. 2, 5
of Copris). In many insects it is wanting ; in other instances it occurs
as a two-jointed filiform appendage, and this is then the second internal
maxillary palpus, as already Uliger * very correctly indicated. It is
exactly where the lobes border upon the stalk that the maxillary palpi
are also inserted.

The underlip, or labium (plainly labium , or labium inferius ), which
is that organ that assists to close the orifice of the mouth from below
(PI. III. f. 12 and 13, q). It consists of two chief parts, each of which
may be considered as a separate organ ; — these are,

The chin {mentum, PI. IV. f. 3 and 4, a, a), a thin, sometimes trian-
gular, sometimes of the shape of a segment of a circle, or trapezoidal
corneous plate, deeply emarginated upon its anterior side, and con-
nected, like the upper lip, to the clypeus, by means of a membrane.

See Kaefcr Preussens, 1 Vorrede, p. xxxvi. note 15.

PARTIAL ORISMOLOGY.

with the margin of the throat (the sternum capitale of some entomolo-
gists), and forms from beneath the inferior covering of the mouth.

The tongue ( ligula , Fab.; lingua, Kirby and Spence, PL IV. f. 4, b)
reposes internally upon the chin. It is, in general, a membranaceous
or more or less fleshy organ, which frequently protrudes beyond the
anterior margin of the chin, in which case its exterior inferior side
is horny ; this horny part is then called tongue-bone ( os hyoideum ),
or fulcrum {fulcrum). The labial palpi ( palpi labiales ) are close
to this, and indeed frequently inserted upon it. The upper fleshy part,
the true tongue, is frequently simple, and visibly separated from the
chin (PI. IV. f. 5), as in the Orthoptera and Neuroptera; in other cases
it is divided, and very closely connected with that organ {Coleopter a) .
In the wasps it is separated into several (three or four) lobes. In the
bees it projects as a long cylindrical, frequently pubescent, retractile
filament : in some of the fossores {Scolia) this filament is divided into
three.

Illiger and Latreille call the tongues of insects with a masticating
mouth the labium ; in Fabricius, on the contrary, the labium is some-
times our mentum, and sometimes, when the chin and tongue are not
distinctly separated, the whole inferior flap of the mouth.

The already frequently mentioned feelers {palpi) are the auxiliary
organs of a masticating mouth ; they are many -jointed and but seldom
simple appendages, inserted upon the maxillae and labium. Those upon
the maxillae, the maxillary feelers ( palpi maxillares , PL III. f. 16,
a), generally originate from where the scale is connected with the
external lobe, and are united to it by a very supple hinge. The
labial feelers {palpi labiales, PL IV. f. 3. c, c) are placed late-
rally upon the labium, close to the tongue, more or less approximate to
the part where it projects beyond the chin {Cerambycina, Carabodea) ;
in other instances they are decidedly inserted in the margin of the chin
{Libellula, Lamellicornia). The number of the joints of these organs,
whose length, form, and relation to each other, is very various, never
exceeds six ; and, in general, the labial palpi have fewer joints than
the maxillary. We have already spoken of a third two-jointed pair of
feelers — the internal maxillary palpi {palpi maxillares interni ,
PL III. f. 17, 5, and PL IV. f. 10, 5), which are found only in the tiger
beetles {Cicindelacea), the Carabodea, and the water beetles, and which
are analogous to the helmet {galea) of the Orthoptera .

THE HEAD.

§ 69.

Before we pass on to our general consideration of the organs "of the
suctorial mouth, we must give the most remarkable differences of the
above-named masticating organs ; but we will first notice the relations
of the head to the thorax, as well as the proportions of its own parts.

We observe in the head the direction in which its longitudinal
diameter stands to the axis of the body. If they form one plane,
it is called prominent ( prominens , Elater ) ; porrect when it pro-
jects, likewise horizontally, far from the thorax (Agra) ; nutant
( nutans ) when its longitudinal diameter forms an obtuse angle with
the axis of the body ( Feronia , Amara, Harpalus ; perpendicular
(perpendicular e) is when its longitudinal diameter forms a right angle
with the axis of the body ( Saperda , Diptera , Hymenoptera ).

We must next observe the manner of its connection with the thorax.

Free ( exsertum or liberum) is a distinctly visible head, never
covered by the thorax {Agra, Anthia , Hymenoptera , Diptera).

Inserted ( insertum ), when it is partly, particularly the occiput,
concealed within the thorax.

Retracted ( retr actum ), when it is concealed as far as the brow
within the thorax {Buprestis).

Concealed ( absconditum ), when it is entirely withdrawn within
the thorax, or is covered above by the thoracic plate {Cassida).

Retractile ( retractile ) when a thus concealed head can be pushed
forwards at the will of the insect {Hister).

Versatile ( versatile ), when it can be freely moved every way
( Hymenoptera , Diptera).

From its anterior margin it is distinguished into clypeate head
(c. clypeaium, PL IV. f. 6), when tolerably flat, and the margin of the
clypeus and the front are produced into a broad border ( Copris , Ontho-
phagus, Ateuchus) ; turreted (c. turritum, PI. IV. f. 7), when it is
produced anteriorly and above into a pyramidal point {Truxalis).
We have already mentioned horned (c. cornutum ) and rostrate
(c. rostratum ) heads. A head furnished with swollen cheeks is called
buccate ( c . buccatum, PI. IV. f. 1, Myopa).

With respect to the differences of the masticating organs themselves,
we shall proceed as we did in their description, by taking them
consecutively.

The upper lip, or labrum, differs as to its figure, surface, margin.

PARTIAL ORISMOLOGY.

and relation to the other organs of the mouth ; there are, however, no
differences exclusively peculiar to it, and we may consequently refer to
General Orismology for the notification of its discrepancies, without the
necessity of repeating them here.

In explaining the construction of the upper jaws ( mandibulce , PI. IV.
f. 8), Kirby and Spence have, and we think very happily, instituted
a comparison with those of the superior animals. They consequently
distinguish the prostheca {prostheca) in the mandibles, which is a
cartilaginous process, near the base within, and is found very generally
among the Brachyptera ; for example, in Staphylinus maxillosus.
They call teeth ( dentes ) the pointed processes on the inner side,
and very skilfully distinguish the superior, compressed, sharp edge as
cutting teeth ( dentes incisivi, the same figure, a) ; or they call
them canine teeth ( dentes laniarii, s. canini), when they are very
sharp and conical. Grinding teeth ( dentes molares') are the inferior
thicker teeth, provided with a broad grinding surface ( Melolontha ).
The mola, or grinding surface ( mola , the same fig. 6), they call the
broad, flat, and often, like the teeth of the elephant, ridged space of the
molares of many insects (for example, of the JBombi , Melolontha, &c.).
In the Coleoptera, this molar tooth is clothed laterally with short stiff
hair, which Straus calls the brush ( hrosse ). The processes at the
base are also important, from their supplying the articulation of the
mandible with the head ; they are three in number, and are placed at
the ends of the edges, beneath which the three surfaces of the mandibles
join. The lower one, viewing the mandible in its natural position, is
shaped like a ball, and corresponds with a cavity, or socket, in the
head. The upper one, on the contrary, is concave, and consequently
forms a socket corresponding with the ball upon the head-case (the
same fig. d). The third is less observable, and lies within towards the
orifice of the mouth, at the end of the masticating edge of the mandible
(the same fig. e). The muse, adductor mandibulce is attached to it ;
its antagonist, the muse . abductor, is inserted in the exterior margin,
between the two articulating processes. The upper jaws very gene-
rally consist of a firm corneous substance ( mandib . cornece ) ; in other
instances they are membranaceous {m. membranacece), as in the Lamelli-
cornia coprophaga : in these also they have in general a hooked shape.
In the Hemiptera, and many Diptera, they are setaceous ( 'm . setaceae,
setae rostri) ; but in other families of the latter order ( Tabanica ) they
are lanceolate (m. lanceolatce) .

Very similar forms are observable in the under jaws (maxillae). The

THE HEAD.

teeth upon the inner margin of the maxillae, when present, are more
uniform, finer, and more delicate ; they are frequently, however, wholly
deficient, and in lieu of them there are short bristles. In other instances
the whole superior process of the under jaw is clothed with short hair,
and such maxillae are called penicillate (max. penicillata, PI. IV.
f. 9) ; for example, in Lucanus. But this superior lobe presents itself
much more generally as a pergameneous, variously-shaped plate (max.
membranacece, PL IV. f. 2). They are setose (max. setose, s. setce
rostri inferiores) in the Hemiptera and many Diptera ; in some of the
latter ( Tabanica ) also lanceolate (max. lanceolatce). They are
unguiculate (m. unguiculatce), when the terminal tooth is moveable,
and can be moved to, and withdrawn from, the internal margin of the
superior lobe at the will of the insect (PL IV. f. 10). This superior
development of the lower jaw has hitherto been detected only in the
tiger beetles ( Cicindelacea ).

We shall find the differences of the labium much more various than
any of the yet examined organs, probably by reason of its being more
compact than either of the others.

We will first observe the chin, upon which we may almost repeat
what we said above of the labrum ; the differences of form are also
found in many other organs, and thus, as general, have been already
described in the first chapter. One peculiarity is its being more or less
deeply divided into two or three lobes, as well as its globose convexity
in the dragon-flies ( Libellulina , PL IV. f. 11). The tongue also has but
few exclusive peculiarities, and these we have already mentioned ; con-
sequently nothing further remains to be said upon it. The under-lip
of the larvae of the dragon-flies is of a very singular nature. The chin
is a thin stalk, which, in its pliable articulation, can be withdrawn
to the prothorax. Attached to it in front, and similarly articulated,
is the flattened, nearly longitudinal, heart-shaped tongue, which, in
repose, closes the orifice of the mouth, but which can also be distended
as a prehensile instrument. In front of the tongue there are two claws,
which, like the nippers of a pair of tongs, move in opposition to each
other, and thus capture objects between them. With these the larva
seizes its food, which consists of small water-insects, and then with-
draws its chin and tongue, so that its prey is brought directly in front
of the orifice of the mouth, when it very quietly sucks the insect dry.
The claws are analogous to the labial palpi.

Much more various is the construction of the palpi. With respect
to the number of their joints they are subject to great variety ; but the

PARTIAL ORISMOLOGY.

maxillary palpi have never more than six, and the labial palpi but
seldom so many as four joints. In every order a certain relation
between their numbers appears to be followed, to which, however, there
are a few exceptions. In the Colecptera, for example, the maxillary palpi
have very generally four joints — the labial palpi three ; in the Orthop-
tera, the former five — the latter three ; in the Hymenoptera , the former
six — the latter four, but with very many exceptions, particularly in
the maxillary palpi ,* for example, Sirex has but one joint. Among
the Neuroptera these numbers are five and three ; among the Lepidop-
tera, two, or more rarely three joints in both ; the Diptera have one,
two, or four joints. The Hemiptera are destitute of palpi ; but if the
jointed sheath of the promuscis may be considered to represent them,
we shall also here very generally find three or five joints.

The most usual shape of the feelers is filiform (palpi filiformes ,
PI. IV. f. 12, a) ; that is to say, such which have all their joints of an
equal cylindrical shape ; moniliform ( p . monil formes), when the joints
are globose, like beads ; setaceous ( p . setacei ), when tolerably long
palpi become gradually thinner, and the last is pointed. On the con-
trary, they are conical (p. conici , PI. IV. f. 13, a), when the joints are
very short, and each successive one is smaller than the preceding (the
Curculionodea). The greatest differences, nevertheless, proceed from
the form of the terminal joint, for the first ones are almost invariably
cylindrical or ovate, and the last only differs in its form. We have
thence the following designations : —

Securiform (p. securiformes , PI. IV. f. 14), when the last joint
is broadly triangular, and hangs by a point to the preceding ( Securi
palpata) .

Lunate ( p . lunati , PI. IV. f. 15), when the same joint has the form
of a half-moon ( Oxyporus ).

Fasciculate ( p.fasciculati , PI. IV. f. 16), when it is split into
many threads and processes ( Lymexylon ).

Lamellate ( p . lamellati, PI. IV. f. 17), when they are divided
longitudinally or transversely into several leaves ( Atractocerus ).

Subulate (p. subulati, PI. IV. f. 19), when the last joint forms
with the preceding a fine and delicate termination ( Trechus ).

Clavate ( p . clavati , PI. IV. f. 20), when the whole organ becomes
thicker towards its apex ( Trox ).

Wedge-shaped ( p . cune formes), when the last joint has the form
of a wedge, which is attached by its sharp end to the preceding joint
( Carabus , Calosoma , Cyclirus, PI. III. f. 16, c ).

THE HEAD.

Turgid ( p . turgidi, PL IV. f. 22), when the last joint has the
appearance of a distended bladder ( Gryllotalpa ).

Excavated ( p . excavati, PL IV. f. 23), when the same joint is
concave at its extremity. (Compare below in the Anatomy of the
Organs of the Senses, § 198).

Truncated ( p . truncati), when the last joint appears to terminate
abruptly ( Prionus ).

Divided (p. ßssi), when the last joint is divided longitudinally.

Pilose (p. pilosi), when the joints are covered with sharp stiff
bristles ( Cicindela , PL IV. f. 10).

Squamose ( p . squamosi ), covered with broad scales ( Lepidoptera ,
PL IV. f.24 and 25).

Elongate ( p . elongati ), are those palpi which stand freely from
the mouth ( Carabus ).

Short ( p. brevissimi) , when, in looking at the mouth, they are not
perceived ( Curculionodea , Libellulina) .

Very long (p. longissimi) , when they are longer than the head, or
even than the antennae ( Hydrophilus ).

Unequal (jo. incequales), when single joints take a different form
(j Banchus, Ichneumon, PL IV. f. 26).

Equal (p. cequales), on the contrary, when this is not the case.

Suctorial Organs of the Mouth.

§ 70 .

The suctorial organs ( instrumenta suctoria ) are, fundamentally,,
merely the masticating ones transformed, or rather those stopped upon
a lower stage of development, for a precise investigation clearly redis-
covers the same identical organs. We however find no general uniformity
among them, excepting in their function — that of taking nourishment
by suction ; for every order of insects with suctorial organs has a pecu-
liar and then throughout all the families which compose it, a very
uniform structure.

We thence distinguish the following principal forms: — the pro-
boscis ( proboscis ), or haustellum Qiaustellum) , we find in the
Diptera only. It consists of a membranaceous or more or less fleshy
organ, which descends in a perpendicular direction from the orifice of
the mouth, and which in general shortly from its origin is geniculated
forward, and terminates in a flapper-shaped suctorial surface. Upon the

PARTIAL ORISMOLOGY.

superficies of this membranaceous sheath, and generally at the angle of
the knee, is found the mouth, covered by a small horny flap, and sur-
rounded by several bristly or lanceolate organs. Frequently, indeed,
this muscular sheath consists merely of a corneous channel, in which
the bristles lie (for example, Culex ) ; and when thus formed, Fabricius
calls it haustellum ; but the muscular sheath itself, proboscis — styled
by Kirby and Spence the theca.

The following, however, is the definition of these parts : — The
sheath (PL V. f. 1. a), whether it be muscular or horny, represents
the under lip, and is thence called labium , and the upper portion of
the knee the stalk ( stipes ) ; when horny posteriorly, it is the chin
( mentum ). The anterior terminal flap is merely a feeler, and
represents the labial palpi, which also only serve to supply the place
of a muscular lip; it is called the knob ( capitulum , PL V. f. 1, a).
Upon the stalk, close to where the bristles, or setae of the mouth are
found, are placed the, from one to four-jointed, palpi (PL V. f. 1 — 7-
c, c). The setae themselves are concealed by the superior, broader,
somewhat convex, upper lip (PL V. f. 2 a, 3 a, and fig. 5, sheath,
vagina, Fab., valvula, Kirby and Spence); beneath it lie from one to
five setae, the two upper ones of which represent the mandibles (the
same, b. b. the knives, cultelli, of Kirby and Spence) ; the two lower
ones, the maxillae (the same, c, c, the lancets, scalpella, of Kirby
and Spence); the middle one, the tongue (the same d, here called
glossarium) ; between them lies the mouth (the same, fig. 5, e).
When there is but one seta, it is the tongue : it is also the true
piercing instrument, which is pushed down into the upper channel of
the under lip ; and thus embraced by the terminal flaps, pierces into
the aliment ; the jaws move up and down by its side, and form, while
the suctorial ventricle distends, a decided pump, in explanation of
which we shall go into greater detail further on.

The promuscis ( rostrum , — promuscis of Kirby and Spence, PL V.
f. 8) is peculiar to the Hemiptera. It is much more uniform in its
construction than the proboscis, although it generally consists of the
same identical parts. We must distinguish in it the small triangular
plano-convex upper lip, ( labrum , fig. 8, 9, and 11, a, from above,
fig. 14 from beneath), which incases the commencement of the pro-
muscis from above, and is attached to the clypeus ; and the, from three
to five-jointed, sheath (fig. 8. b), which consists of two equal lateral
flaps, which may represent the maxillae and their palpi, and four fine
setae (fig. 10, c, c, and d, d), which, as in the flies, are analogous to

THE HEAD.

the upper and under jaw. Between them is found the orifice of the
mouth, at the apex of a small lanceolate tongue, concealed within the
sheath (fig. 10, e, and fig. 13, e), which is enclosed by the setae of the
jaws. The jointed sheath of the promuscis is called vagina ; the setae
of the jaws, setae superiores et inferiores ; the central tongue, ligula.

The spiral tongue (lingua spiralis, Fab. ; antlia, Kirby and
Spence ; spiritrompe, Lat.), or sucker of the Lepidoptera , is the
third form of a suctorial mouth* It equally consists of all the organs
of a masticating apparatus, which, however, here, adopt the following
configuration. A small triangular piece attached to the clypeus, and
which extends downwards towards the mouth, is the labrum (fig. 15,
a, and fig. 16) ; near to it are placed the short, conical, slightly-bent
mandibles (fig. 15, b, b, and fig. 17). They are both covered by the
large forwardly-bent labial palpi (PI. VI. f. 3, d ), and can be dis-
covered only by a very laborious research. The maxillae have the
same form they are described to take above in the masticating appa-
ratus ; but the superior lobe is stretched into a long, cylindrical,
transversely-wrinkled filament (PI. VI. f. 1, a ) ; at the inner margin
of which, two narrow bands are found (fig. 2, a, a), which symme-
trically agree with those of the other maxilla, and by means of which,
therefore, the space occurring between the two maxillae is formed into
a tube (fig. 2, o). The filiform maxillae are also hollow (fig. 2, p, p ),
and by these cavities they are connected with the furcate commence-
ment of the aesophagus, so that the Lepidoptera have, as it were, two
mouths, or rather two separated suctorial tubes. Where the upper
filament of the maxilla is attached to the stalk, a small two-jointed
feeler (fig. 1 , b) is inserted. The labium (PI. V. f.18, e, and PI. VI,
f. 4, e ), is tolerably large, generally triangular, and frequently divided
at its apex. Each lobe bears a large, three -jointed, very hairy
feeler (PI. V. f. 18, d, d, PI. VI. f. 3 and 4, d, d), which falls
forward, and forms the sheath of the sucker, when it is drawn up
spirally in repose.

The suctorial organ of the bees (PI. VI. f. 2 — 9, see description of
the plates), and of the other suctorial Hymenoptera, is but a more or
less prolonged transformation of the masticating apparatus, the same
as that of the May flies ( Phryganeodea ), and we shall therefore treat
of them in detail in our systematic description of their families. The
mouth of the flea (. Pulex ), to which Kirby and Spence ascribe a
peculiar suctorial organ, does not essentially differ from the structure of
those of the Diptera, which have no fleshy lip ; and which we shall also

PARTIAL ORISMOLOGY.

treat of in its proper place. The same observation refers likewise to
the lice ( Pediculi ).

The Eyes.

§ 71.

Having now concluded this detailed description of the oral apparatus,
we can pass on to the consideration of the other organs, and the eyes
occur as the most immediate objects to proceed with.

The eyes plainly ( oculi , PI. III. f. 11, 12, 13, a. a., PL V. f. 15, a.,
PI. VI, 3 and 8, a. a.) also called compound eyes ( oculi compositi ),
are placed at the sides of the head, above the mouth, and generally
present themselves as large hemispheres, the superficies of which, at
least upon close investigation, appear to consist of numerous regular
hexagonal surfaces. They are generally circular in circumference, but
many other figures (as oval or kidney-shaped) are observable in
them. Each of the above hexagons is itself an eye (as we shall more
explicitly illustrate below in the Anatomy of the Eye), their surfaces
consequently are so many slightly convex horny cases, whence the quick
sight of these creatures is readily explained. Their margins of sepa-
ration are often thickly set with hair ( oculi pilosi ), in other instances
they are naked ( oculi nudi ). The number of these lenses or facets
has been calculated by several authors, and their almost incredible
multitude has very justly excited astonishment. Hooke counted 7,000
in the eye of a house fly ; Leuwenhoek more than 12,000 in the eye of
a dragon fly ; 4,000 in the eye of a domestic fly ; and Geoffroy cites a
calculation, according to which there are 34,650 of such facets in the
eye of a butterfly. They must also necessarily be very numerous in
the eye of the Lamellicornia, in which, even under a tolerably strong
lens, the divisions are not perceptible, whence Fabricius * called them
simple eyes.

The general rule is for the eyes to be separated by the brow ( oculi
distantes), but they frequently join closely together in male insects
{oculi approximati, for ex., in the dragon flies, the male Syr phi, the
Drones). There are, in general, but two of these compound eyes, but
a few exceptions are found to the universality of its application in the
whirlwigs ( Gyrinus ), and some Ephemera , which have absolutely four

Philosoph. Eut. p. xix, § 4.

THE HEAD.

eyes. In some of the Coleoptera, a corneous process originating at the
clypeus ( canthus of Kirby and Spence), either completely or partially
divides the eyes, and these beetles, ( Ateuchus , Geotrupes, Fabricius, &c.
&c.) then appear to have four eyes. The genus Telraopes, also, among
the Capricorn beetles ( Cerambycina ), has apparently four eyes, from
the antennae being inserted exactly in the middle of the long ovate eyes,
and which thence seem divided into an upper and lower half.

The simple eyes or auxiliary eyes ( ocelli , oculi simplices, PI. VI,
f. 8, b, stemmata, Kirby and Spence), are generally three in number,
and more rarely we find but two. They are placed upon the vertex or
upon the brow, most frequently in a triangular position ; they are
much smaller than the true eyes, and consist of but one very convex
case. They are found in all the orders of insects ; among the Cole-
optera, indeed, only as exceptions *, in others, the Diptera, for
example, very universally. The larvae of insects with a perfect meta-
morphosis are destitute of compound eyes, and instead of them have
mostly simple eyes ; in many instances they have none.

The Antenna (Antenna;).

§ 72.

The Antennae must be distinguished as the third most important
group of the organs of the head. They are two jointed organs, one
of which is placed upon each side of the head between the angle of the
mouth and the eyes. They appear never to be wanting, and there are
never more than a single pair present. In some parasites only ( Philop -
terns , Docophorus) , there is close to and in front of each of them a small
moveable stalk, which Nitzsch has called the little beam ( trabeculus ).
It is different in the classes nearest to that of insects, the Crustacea ,
Myriapoda , and Arachneodea ; in which we find sometimes none,
sometimes only two, and even four, or six antennae.

As the differences of antennae are very great, we must divide our
consideration of them under several heads. These are their situation ,
relation to the body , their general construction , construction of the
individual joints , and their clothing.

* Germar discovered them in Omalium ; they were afterwards discovered in Antho-
phagus and Paussus. A very particular observer, on the contrary, Straus-Durckheim,
denies their being eyes, although he does not dispute the existence of the points, page 58.

PARTIAL ORISMOLOGY.

1. Situation of the Antennae.

Frontal {ant. frontales ), they are called when they are inserted
directly upon the brow {Bees, PL VI f. 8, c, c).

Preocular {ant. prce ocular es), are such as are inserted close to the
front of the eyes ( Carahus , PL III. f. 11 and 13, y, y , y).

Interocular {a. interoculares), when they are placed between
both the eyes.

Extra-ocular {a. extra-ocular es'), when placed very distant from
the eyes.

Inocular {a. inoculares), when the eye surrounds the base of the
antennae ( Cerambyx ).

Infra-ocular (a. infra-ocular es), when inserted beneath the eyes.

When they are placed, as is usual, upon the upper part of the head,
they are called superior {a. superior es); but when beneath, inferior
(a. inferiores).

When their basal joints are inserted very closely together, they are
called approximate («. approximates) ; but when they are wide apart
they are styled distant (a. distantes).

2. Relation of the Antennae to the Body.

Elongate ( elongates ), when of the same length as the body ( Lep -
tura).

Longer ( longiores ), when longer than the body {Saperda).

Verst long ( longissimce ), when they are considerably longer than
the body ( Lamia cedilis), Fab.).

Short {Irenes), when about the length of the head.

Shorter (hreviores), when they are longer than the head, but
shorter than the body.

Verst short ( brevissimee ), when not so long as the head.

3. Forms of entire Antennae.

Antennae which entirely consist of equal joints are called equal
{equales), whereas those whose joints are dissimilar receive the name of
unequal {inequales). Both kinds are subjected to various differences,
which we will now proceed to consider.

THE HEAD.

a. Equal Antennce.

Setaceous ( setacece , PJ. VII. f. 1), are such which very gradually
decrease, becoming pointed at the apex ( Locust a , Fab.).

Setiform ( setiformes , PL VII. f. 2), when it resembles a slender,
short bristle which springs from a thicker basal joint ( Libellula ). This
form is distinguished from the subulate ( subulata , PL VII. f. 3), by
the latter being shorter, thicker, and slightly bent ( Leptis ).

Filiform ( filiformes , PL VII. f. 4), when of the same thickness
throughout, and composed of cylindrical joints ( Carabus).

Moniliform ( moniliformes , PL VII. f. 5), is when the joints are
globose ( Tenebrio ).

Ensiform ( ensiformes , PL VII. f. 6), when the joints are com-
pressed, and have a sharp edge on each side ( Truxalis ).

Falciform ( falciformes , PL VII. f. 7)> when arched like a sickle.

Dentate ( dentatce , PL VII. f. 8), when their joints are armed with
slight, pointed spines ( Stenochorus ).

Serrate (ser rates, PL VII. f. 9), when the joints are triangular,
and are so arranged that the prominent angle is placed anteriorly, and
inclines downwards ( Elater ). Biserrate (biserratee), when a similar
angle is also placed upwards, and, when so, the point of insertion of the
joints is not at the superior angle, but at the centre of the base of the
triangle. In the latter case, the joints of the antennae form an isosceles
triangle, whereas in the former they are more or less rectangular.

Imbricate ( imbricates , PL VII. f. 10), is when the joints are
conical, but deeply excavated, so that one joint is inserted half way
within the other {Prionus).

Pectinate ( pectinatee , PL VII. f. 11), when the joints have long
processes on one side, like the teeth of a comb. Bipectinate
(bipectinatee), when such a process issues from each side of the joint
( Lophyrus ) ; or doubly pectinated ( duplicato-pectinatce , PL VII.
f. 12), when there are two processes on each side of the joints
( Ctenopliora ). Cirrate ( cirratee , PL VII. f. 13), when the branches
of such doubly or singly pectinated antennae are very long and
curled, and sometimes, but not always, fringed with hair. Distichous
{distiches'), when the processes originate from the apex of the joint,
and do not incline at right angles towards the sides, but bend for-
ward at acute angles. Flabellate ( flabellatce, PL VI L f. 14),

PARTIAL ORISMOLOGY.

are pectinated antennae, whose joints are very short , but the processes
are very long and flat, and consequently lie close together. Bifla-
bellate (biflab ellalce) , when both sides of the joints send forth such
processes.

Branched ( ramosce ), when some of the joints only send forth pro-
cesses upwards (PI. VII. f. 15). This form should, by rights, be
placed under the following head ; but as they are in general filiform
antennae which are furnished with such appendages, and they con-
sequently bear great resemblance to the preceding forms, we have
preferred introducing them here, among those they were most like.

Forked (furcatce, PL VII. f. ]6), is when throughout its whole
length it is separated into two branches or prongs ( Scliizocerus ,
Lat.).

b. Unequal Antennce.

The inequality of antennae proceeds chiefly from the differing
form of their second and last joint, on which account they demand
especial notice. Very generally the first or second joint is much
longer than the following, and is also not placed in the same direction
with them, but the third joint is inserted laterally upon the second at
a right angle. Such antennae are called broken ( fractce ), or genicu-
late ( geniculatce , PI. VII. f. 17) ,* and the long joint is distinguished
as the scape (scapus, the same, a ), and the following as the branch
(flagellum, the same, 5).

The branch of such geniculated antennae is frequently merely cylin-
drical or filiform ( Apiaria , fig. 17) ,* in other instances, on the contrary,
the joints of the branch differ again from each other. We thence dis-
tinguish many forms which are also found in not geniculated but
merely unequal antennae. The following are of this description : —

Clavate ( clavatce , PI. VII. f. 18), when the joints become gra-
dually broader, so that the whole organ assumes the form of a club
( Silpha ).

Capitate ( capitatce ), or such whose terminal joint forms a large
round knob. If the knob is formed by but one joint, it is called simple
( capitulum solidum ); but when composed of several, it is called, in
contradistinction, compound ( capitulum compositum , PI. VII. f. 19,
Necrophorus ). Perfoliate (cap. perfoliatum) , when the joints of
the knob slightly stand off from each other all round ( Hydrophilus ,

THE HEAD.

PI. VII. f. 20) ; lamellate ( cap . lamellatum), when the joints of
the knob extend on one side into broad leaves (PI. VII. f. 21,
Meloloniha ) ; tunicate ( cap . tunicatum ), when each successive
joint is buried in the preceding funnel-shaped one (PI. VIII. f. 1,
Letlirus ) ; inflated {cap. inflatum), when the knob has the form of
a broad bladder (PI. VIII. f. 2, Paussus') ; split {cap. fissum), when
the joints upon one side are divided as by incisures (PI. VIII. f. 3,
Lucanus ).

Hooked ( uncinatce ), when the last joint bends back upon the
preceding (PI. VIII. f. 4, the male of Odynerus).

Nodose {nodosce, PI. VIII. f. 5), are those antennae which have
their intermediate and terminal joints thicker than the remainder
(many Curculios).

Angustate {angustatce), on the contrary, when the middle joints
are thinner than at the beginning or the end (PI. VIII. f. 6, Asilus).

Setigerous ( seligerce ), are such whose terminal joint has upon its
upper side a fine bristle {seta). The bristle is either simple {sim-
plex, PI. VIII. f. 7), or plumose {plumosa, PI. VIII. f. 8, Volucella ),
when upon each side it sends forth fine and delicate branches. These
forms are in general only found in the three-jointed antennae of the
Diptera, the very various forms of which are shown in the figures
6 to 17 of the eighth plate.

Mucronate {mucronatce) , are those whose last thick joint suddenly
terminates in a sharp point (PI. VIII. f. 18, Empis ).

Auriculate {auriculatce), are those antennae whose inferior joint
is distended into a concave plate, not unlike the shell of an ear, and
which partially covers the rest (PI. VIII. f. 20, Gyrinus ; f. 19,
Parnus).

Irregular {irreguläres), lastly, are all such antennae, all or several
of the joints of which are dissimilar in form to each other (PI. VIII.
f. 22, Cerocoma ; f. 30, Agaon).

4. Number of the Joints.

Antennae which consist of but one joint are called exarticulate
{exarticulatce) ; others, which have but few joints, are named from
their number, as biarticulate, with two ; triarticulate, with three
joints, &c. But those whose joints are very numerous are called
multiarticulate ( multiarticulatre).

F 2

PARTIAL ORISMOLOGY.

The number of the joints of the antennae is tolerably regular, and
only varies in the different orders and families of insects ; but a few
only, as the Diptera pupipara , have exarticulate, or one-jointed
antennae ; the majority of the rest of the Diptera, such as the true
flies ( Muscaria ), and Syrphi, have three joints (see PI. VIII. f. 6
and 8—14, and 16 and 17)- Just so is it in the genera Nepa and
Ranatra (PI. VIII. f. 21), in the family of water-bugs (Hydro-
corides') ; while the remaining genera of these, as also of the field-bugs
( Geocorides ), have four joints, with the exception of the five-jointed
genera, Pentatoma, Tetyra, and Reduvius. All the Cicadaria have
three joints, with the exception of Cicada, Lat. ( Tettigonia , Fab.)^
which has five. The genera Asilus, Dioctria, Dasypogon, Hilara,
Empis, and Sargas, among the Diptera , have five joints (PI. VIII.
f. 7 and 18). It is the same in the apterous flea ( Pulex ), the lice
( Pediculi ), and the genus Philoplerus, among the equally apterous
parasitic skin-destroyers (Dictyotoptera mallophaga). Two other
genera of this family, viz. Liotheum and Gyropus, have but four
joints; the fourth genus, Trichodectes, has but three. Six-jointed
antennae are rarely found, the genus Perga , and some species of the
genus Cimbex, among the Hymenoplera, display this number; and
among the Diptera , the^genera Hcematopoda , Hexatoma, Meig. ( Hep -
taloma, Latr.), and Nemalocera, Meig. ( Hexatoma , Lat.). From seven
to EiGHT-jointed antennae are found in other Diptera, in the genera
Stratiomys, Oxycera, Tabanus, Pangonia, Chrysops ; but the last five
or six are so closely attached together, that they appear to form but one
joint. Nine joints are found in the hymenopterous genus Tenthredo ;
ten in the approximate genus Athalia. ELEVEN-jointed antennae are
possessed by the Coleoptera, with a few exceptions ; for example, ten
in Melolontha, Oryctes ; nine in Copris , Oniticellus , Ateuchus , Apho -
dius, Geniates, Kirby; Phanceus, Leach ( Lonchophorus , Germar), and
many of their affinities ; eight, Dorcatoma and Calandra ; five.
Platypus and Claviger ; two, Paussus. More than eleven joints
are found in some species ; for example, twelve in Cebrio gigas,
Chrysomela stolida, some Saperda, and the males of the genera
Stenochorus and Trachyderes. In Prionus imbricornis the female has
nineteen, and the male twenty joints; Rhipicera marginata, Latr.
( Polytomus , Dalm.) has thirty-two joints ; Rh.femorata , twenty-
three ; Rh. mysticina , even forty. Among the bees, wasps, and the
other families of the Hymenoptera aculeata, the female has twelve.

THE HEAD.

and the male thirteen joints. The Biptera, with unform and multi-
articulate antennae, possess a varying number; Bibio , Latr. ( Hirtcea ,
Fab.), has nine ; eleven, Bilophus , Scatopse , and Simulia; the Tipu -
laria , from thirteen to seventeen; and all the Tipularice fungivorce
have sixteen. Multiarticulate (20 — 50) antennae are found among
the Lepidoptera ; the most of the Ichneumonodea and Urocerata ; all
the Neuroptera , and the most of the Orthoptera ; but in many species
of the genus Locusta, Leach, there are found fourteen or sixteen ;
in Gryllus, Fab., not many more than twenty ; in Forficula, some-
times only twelve or fourteen, but even as many as thirty.

5. Forms of the individual Joints.

They are in general cylindrical {teres, s. cylindricus), but the
joints become very frequently thicker towards their end, and conse-
quently not unusually adopt an obconic form ( a . ohconici ). Bell-
shaped, or campanulate ( a . campanulati ), are those which are con-
cave at their broadest end (Pi. VII. f. 10). Torulose ( a . torulosi),
such as have greater or smaller tumours upon them. Those which
are produced laterally into lobes or processes [art. lobati, s. producti ),
have been previously mentioned. Moon-shaped, or lunate joints
{art. lunati), are found in the male individuals of the genera Nephro -
toma zndiEucera (PI. VIII. f. 29). The first conical joint upon which
the antenna turns like a ball within a socket, is called by Kirby and
Spence the torulus ( torulus ).

6. Clothing of the Antennce.

The great majority of antennae are completely naked ; others, on the
contrary, have a clothing consisting of shorter or longer hair, in which
case the terms explained above (§ 25) may be applied to them. Some
peculiar terms, however, may here find a place.

Verticillate ( verticillatoe ), are those antennae, the joints of which
are surrounded, at equal distances, with stiff hair ( Erioptera , Psychoda,
PI. VIII. f. 23).

Fimbricate ( fimbricatce ), on the contrary, when the long parallel
hair is placed only upon one side of the joint ; or pectinato -fimbricatce,
when the antennae are at the same time pectinated ( Phalcena , PI. VIII.
f. 24).

PARTIAL ORISMOLOGY.

Bearded ( barbatce ), when the short and thickly-set hair' covers the
antennae completely upon one side.

Fasciculate (fasciculatce) , when every joint has a distinct pencil
(Callichroma alpinum , PL VIII. f. 25).

Scopiferous ( scopiferce ), when a thick brush of hair is placed upon
one part of the antennae (many species of Lamia, PI. VIII. f. 26).

Plumose ( plumosce ), when the hair clothing the antennae is long,
and is so far apart that each may be distinctly discerned (Chironomus,

PI. VIII. f. 27, f. 28).

THE THORAX.

II. — The Thorax.

§ 73.

The second chief division of the body of an insect, and which
succeeds to the head, and is connected with it by the neck, and
precedes the abdomen, is the thorax ( thorax , stethidium*). In
calling this portion of the body the thorax, we differ from other
writers, who apply this name to parts only of this division of the body ;
but why we do so is readily explained to those who remember the note
to § 9, II, and who agree with us in the rule we there lay down f-

Fabricius divided the body of an insect into caput , truncus , abdomen.
and artus. That this subdivision is inadmissible, is sufficiently ex-
plained at the above-cited place. How this, his truncus, our thorax,
again consists of several divisions, will be more fully shown below.
These segments, or divisions, he named in the following words : —
truncus inter caput et abdomen constat thorace, scutello , pectore ,
sterno f. He called the upper part of the trunk thorax (§ 8) ; pectus
was the part beneath, corresponding with the thorax (§ 10, page 25) ;
sternum, lastly, the central longitudinal line of the breast (§ II). The
term thorax, which Fabricius used sometimes for the dorsal superficies
of the anterior segment of the trunk, as in the Coleoptera, Orthoptera,
and sometimes for the whole superior surface of the trunk, as in the
Hymenoptera and Diptera, was afterwards applied to that whole
division of the body whose superior surface it was intended only to
indicate ; and thence sometimes meant the entire anterior segment,
and sometimes the whole trunk. Illiger sought to put a stop to this

* This term, used by Illiger, Bouche, and others, is less applicable than thorax, because
it is borrowed from the Greek (derived from ffrbS-o;), whilst caput and abdomen are Latin.
It is true, indeed, that thorax also originates from the Greek, but was long used by the
Latin writers of the best period.

*t* Passing over other authorities, we will merely cite in support of our opinion, Ch. L.
Nitzsch. See Germar, Magas, der Ent. iii. band, p. 275, note, who there explains
himself upon the subject.

; Philos. Entom., p. 22, § 7.

PARTIAL 0R1SM0L0GY.

confusion, by applying the terms in general use to signify the parts of
the superior animal, and he therefore called that entire division the
thorax ; and he distinguished its upper surface as the thorax superior,
and its lower one as thorax inferior *. Thus all difficulties were at
once removed. But Kirby and Spence re-adopted the obsolete, incor-
rect nomenclature, endeavouring to justify their course by its priority ;
and in addition to which they named every possible part with such
excessive and painful precision, and even every direction or position of
the body, that the multitude of terms which their imagination has con-
ceived, and, it must be admitted, not always very happily, is sufficient
to excite astonishment. Before them, Knoch had essayed an orismo-
logical detail of the thorax f, but which also does not suffice for every
requisition ; but, that we may be as complete as possible, we will give
a summary of his, as well as of Kirby and Spence’s prolix nomenclature.

According to Knoch, the body of a beetle — for it is only to the
Coleoptera that his names apply — exclusive of its head, consists of
the trunk (tr uncus), which comprises the neck ( collum ), the breast
(pectus), the abdomen, the scutellum, and the wing-cases (elytra).

The neck ( collum , our prothorax) is divided into the upper side
{thorax), and the under side ( jugulum ). In the centre of the under
side is found a prominent narrow portion, the collar-bone (sternum
collar e, cartilago ensiformis, Lin.). That portion of the trunk which
lies between the neck and abdomen, but which above is covered by the
elytra, he calls breast (pectus). This is divided into several portions:
the anterior part placed in the middle, limited posteriorly by the sockets
of the intermediate legs, he calls peristethium ; close to which, on each
side exteriorly, are the scapula, which sometimes ( Cychrus ) are soldered
to the peristethium. Next to the peristethium, and behind the sockets
of the intermediate legs, follows the large central acetabulum ; close to
which, on each side, limited anteriorly by the scapula, are the para-
pleura, or side-pieces, which, in many genera (Cychrus), are divided
into two. Behind the acetabulum and parapleura is placed the
mericeum, which forms the anterior surface of the sockets of the
posterior legs. The breast has frequently, as well as the neck, a
central prominent carina (Hydrophilus) ; this is called breast-bone
(sternum pectorale). The whole upper surface of the breast is called

* Magas. Vol. V., p. 11, No. 1578. ;
+ Neue Beitrage, Book I , p. 41.

THE THORAX.

the back {dorsum), with the exception of the scutellum lying between
the elytra.

The following Orismology of Kirby and Spence is much more
diffuse : —

The trunk ( truncus ) is divided into two chief parts — the anterior
bearing the anterior legs, called manitruncus, and the posterior, ali -
truncus, upon which are placed the four posterior legs and the wings.

The upper side of the manitruncus is distinguished as the prothorax y
and its broad lateral margin as border {ora) ; the patagia , two cor-
neous scales densely covered with hair in the Lepidoptera ; the um~
bones, two moveable thorns on the sides in Acrocinus longimanus ; and
the phragma, the posterior margin descending in front of the alitrunk.
The under side is called antepectus , the central prominent ridge of which
is called prosternum, and the antefurca , which is an internal process
for the insertion of the muscles.

The alitruncus has the following divisions and parts: — the first
division upon which the anterior wings are placed is called above the
mesothorax, or is divided into the collar e, particularly visible in the
Hymenoptera , it appears to be wanting in insects with a distinct
mamtTunk, the propkragma, a thin partition which descends from
the anterior margin of the mesothorax into the cavity of the trunk, and
separates the anterior segment from the intermediate one. The dor -
solum is that portion of the superior surface which lies between the
collare and scutellum, upon which are found the wing-sockets ( plcro ~
pega ). These cavities are, in the Hymenoptera, covered by two small
scales ( tegulce ). The scutellum, a triangular corneous piece placed
behind the dorsolum, and between the superior wings, serves as a point
of insertion of the elytra. The under side of the anterior division of
the alitrunk is called mcdipectus, in which is again distinguished the
peristethium, or anterior central part lying in front of the sockets of
the intermediate legs (the same part of Knoch); the scapularia, placed
exteriorly next to the peristethium ; the mesosternum, the prominent
central ridge of the mcdipectus ; and the medifurca, a forked process
of the interior surface of the medipectus. The superior surface of the
posterior division of the trunk is called metathorax. Upon this is.
found the mesophragma, a separating partition running parallel with
.the propkragma , and descending from the anterior margin of the
metathorax ; the posl-dorsolum, the intermediate piece between the
mesophragma and post-scut el him ; the post-scutellum, that piece which

PARTIAL ORISMOLOGY.

follows the middle piece, and which extends to the end of the meta-
thorax ; pleurae (the sides), the space between the scapularia and the
insertion of the wings. The under side of the posterior division of the
alitruncus they call the post-pectus ; it is divided into the mesostethium ,
the central piece between the intermediate and posterior legs (Knoch’s
acetabulum ) ; the parapleurae , the lateral pieces on each side of the
mesostethium ; the metasternum , the elevated central ridge of the
mesostethium ; the post-furca, the internal descending process of the
metathorax and the opercula , which cover the spiracles of the meta-
thorax.

To whom is not the elaborately strained nature of these definitions
apparent ? To call the anterior legs, hands, and that portion of the
body upon which they are placed, the manitrunk, is certainly a very
forced endeavour to find analogies. The upper surface also cannot be
called thorax, and the under side pectus ; for pectus universally means
the anterior portion of the thorax, and its posterior or upper surface is
called dorsum, or back. It is also erroneous to consider the collare as
a distinct part, as it is evidently what they call thorax in the Coleo -
ptera. Notwithstanding their assertions to the contrary, they will never
be able to convince us of it. Wheresoever a part is not immediately
recognised, it displays no art to give it a peculiar name ; but, on the
contrary, it shows much to prove, by a careful study, the relations of
the several parts in the different orders, and the variations they are
subjected to. This has been the problem which the following sections,
containing a description of the thorax, seek to solve.

§ 74.

The thorax of insects consists of three corneous segments, from each
of which a pair of legs originate ; and the two posterior, or only the
intermediate one, always bear besides a pair of wings. We distinguish
these segments as the prothorax, mesothorax, and metathorax *.
In its most simple conformation, each of these segments is wholly

* Cb. L. Nitzsch, who first proposed these three names for the three segments of the
thorax, wrote protothorax ; but as he himself called the third segment metathorax, forming
it consequently of a preposition and a substantive, the analogously compounded name of
the first segment proposed by Kirby and Spence is, therefore, better than the former.
Had Nitzsch compounded all the three names of ordinal numerals, his would have had
the preference, as being the first ; in consequence, therefore, those proposed by Kirby and
and Spence take precedence.

THE THORAX.

uniform, without further composition, as in all insects deficient in wings,
Pediculus, the Mallophaga, Palex, &c.) In such no distinct parts are to
be noticed, they are consequently named only according to their position,
the upper part being called the back {dorsum), the under the breast
{pectus) and the sides, where they are distinct or prominent, {pleurae).
As portions of the whole superficies they are distinguished by the name of
the segment upon which they are situated ; for example, the upper side of
the prothorax is called the back of the prothorax {dorsum protho-
races). But this most simple construction of the thorax passes through
a great variety of conformation in the different orders, whereby the
undivided segments, here seen, become separated into parts of which
sometimes one, and sometimes the other, is most strongly developed ; but
the three great divisions are always distinctly determined, although in
some cases the second and third, and in others all three, are so closely
united that they appear to form but one undivided whole.

The orders in which we observe the first segment to be most freely
united to the second are the Coleoptera , Orlhoptera, Neuroptera, and
Hemiptera; the other four display a tolerably close union of all the
three segments into one entire undivided thorax. Although this more
distinct separation of the prothorax is evidently conditional upon a not
unimportant transformation of organic relations, we shall nevertheless
observe no new parts in these orders, but be able to show an analogical
structure in all the rest. The greater freedom of union does not seem
to imply a higher grade of organisation, for we observe the same structure
in the apparently highest and lowest orders ; but in the higher orders
each thoracic segment is composed of several parts, which in the lower
ones unite into one, although we even then find the indication of such
separations.

When most fully developed, the thorax consists of four corneous
plates. The superior, which we call pronotum*(P1. IX. and XII. a, a, a,
Prothorax of Kirby and Spence), takes very different figures. In
general it is more or less quadrate, but so that the sides seldom form
straight lines, but either bow out or undulate. The anterior margin is
generally emarginate, the posterior straighter ; the lateral margins fre-
quently dentate, and sometimes armed with strong spines or with smaller
teeth. The centre of the superficies very generally exhibits a narrow
longitudinal impression, which beneath and within projects as a sharp

* This name is compounded of irpo, anterior, and v6tos , the back.

PARTIAL ORISMOLOGY.

corneous ridge. The prothoracic case is thereby divided into two lateral
halves (for example, in Gryllotalpa, PI. XI. No. 1, f. 3, c). Sometimes
the upper surface projects in a similar central pectinated ridge, as in
many of the genus Gryllus, Fabr. ( Acridmm , Latr.) Besides its disc
( discus ) and margin ( margines ), we distinguish upon it the surrounding
border (limbus'). Between this pronotum and the anterior sternal
plate we find on each side in the cursorial ( Carabici ) and natatorial
beetles (Hydrocanthari) , a distinct corneous scale, which, as the muscles
of the coxae originate at them, should be called shoulder-blades; and,
that we may distinguish them from the larger shoulder-blades of the
intermediate legs (which have been long called scapulce), may be called
the smaller or anterior shoulder-blade ( omium *). It is a flat, more or
less heart-shaped plate (PI. IX. No. 1 fig. 4, of Carabus , No. 2, fig. 4,
Dytiscus'), and which forms the posterior portion of the sides of the
prothoracic segment, and is contiguous in front to the wings of the
prosternum , which extend upwards to the pronotum. Its superior margin
turns inwards (the same b*), and forms a broad, bowed corneous
ledge, thus presenting a still wider surface to the muscles of the coxae,
upon which they may spread themselves. In Buprestis, which has
this margin very broad (No. 3, fig. 1, a, a), I found upon its posterior edge
a small round corneous plate, which was distinct from it (the same b, b),
which upon the opposite side was contiguous to the prosternum, and is
doubtlessly the analogue of the anterior shoulder. I have not observed
it in other families of the beetles, in which the turned margin of the
pronotum takes its place (PI. X. No. 3, fig. 1.)

The inferior plate, the prosternum (PI. IX. &c. b, b), has much
more limited dimensions than the superior. It is less flat, rather
inclining beneath to an angle, the edge of which is frequently prominent,
or not rarely prolonged into a mucro posteriorly ( Elater ). Close to the
central ridge the sockets (acetabula) of the anterior legs are seated,
one on each side ; in front the articulating membrane is affixed, and
posteriorly the membrane which connects it with the mesothorax. The
spiracle of the prothoracic segment is found here ; it is a longitudinal
gap surrounded by a callous margin, into which the tracheae of the
anterior part of the body open themselves (PI. XI. No. 1, fig. 2, a , a).
In all those families to which this division of the prothoracic case is not

* The Latin language has no diminutive of scapula , we have therefore derived it from
the Greek, in which language üi/juov signifies a small shoulder.

THE THORAX.

peculiar (for example, the Ceramhycina), the superior plate is united to
the inferior without the indication of any separation, so that the parts
distinguished in the former can be regarded in these only as regions.
The prothoracic case has, besides the feet, no other limbs or peculiar
appendages, with the exception of two instances. In the one, we observe
a moveable spine on each side of the prothorax, ( Acrocinns longimanus ) ;
the second instance is found in the family of the Rhiphidoptera *, on
each side of the prothorax of which a contorted and twisted corneous
appendage is attached. All other prominences of the prothoracic case
are integral portions of it, and are to be considered only as processes.
There is a multiplicity of them and of the most distinct forms, the
families of the Lamellicornia and Cicadaria display the most remarkable.
The patagia ( patagia ) of the Lepidoptera, which Kirby and Spence
consider as appendages of the prothorax, are not seated upon this, but
upon the mesothorax.

§ 75.

In those orders in which the prothorax is in closer connection with
the mesothorax, we often find analogous parts ; but it just as often forms,
as well as the whole thorax, one entire piece, upon the superficies of
which the different parts are indicated by means of deep impressions
and furrows. This is the case in the Diptera and the Neuroptera ;
for, notwithstanding the distinctness with which the different thoracic
plates are marked out, for example, in the Libellulina (PI. XI. No. 3,
f. 1 — 3), they are, nevertheless, firmly attached together, and require
considerable force and art to separate them. In the Hymenoptera , this
separation is not merely indicated, but it actually takes place. A small
corneous plate with two sockets, and seated quite in front of the pro-
thorax, represents in this order the prosternum (PI. XII. No. 1 and 2,
b, b, b.) ; a larger plate, which has a narrow margin, and which,
descending perpendicularly, bows round and extends on each side
to the origin of the wings (the collar of Kirby), takes the place of the
pronotum (PI. XII. No. 1 and 2, a, a.). Kirby and Spence con-
sider this plate as an integral portion of the second segment, and
confirm themselves in this view of it by its generally remaining attached
to the inesothoracic segment when the first pair of legs are separated
from the prothorax. They, consequently, think they have observed

Strepsiptera, Kirby.

PARTIAL ORISMOLOGY.

that some insects ( Vespa, Cimbex ) possess both a collar and a prono-
tum ; and that in others ( Xylocopa ), the collar forms a complete ring.
Their first observation is perfectly correct, but not convincing; it
frequently happens that the first segment of the thorax is more
strongly affixed to the thorax than to the abdomen, and remains attached
to the former when we wish to separate the latter (Hister, Gryllus,
Grylloialpa , &c. &c.) ; the same remark may be made with respect
to the coxa, and with still greater latitude, but which are, notwith-
standing, joints of the legs : why should not, therefore, the pronotum
occasionally be affixed more firmly to the second segment of the thorax
than to the prosternum ? The second observation is absolutely erro-
neous ; for what Kirby and Spence consider as their prothorax, (our
pronotum ), is sometimes the extended membrane of the neck ( Vespa ,
Cimbex'), sometimes a plate, as in the Libellulina , representing the
anterior part of the mesonotum; and which, in the Coleoptera, is
covered by the pronotum. The third observation is also imaginary,
for proportions of that kind are always the peculiarities of entire
families ; and this conformation of the prothoracic segment is found
as little among the rest of the bees as in Xylocopa. Whereas, on
the contrary, the following reasons clearly prove this part to be the
pronotum : —

1st. In all those orders which possess a collar, the pronotum would
fiecessarily be deficient, as they possess no part excepting this which
responds to it. On the other side these orders would have a cor-
neous part more upon the mesothoracic segment than any of those
provided with a distinct and free prothorax , in which we in vain seek
upon the mesothoracic segment for a part analogous to the collar.

2ndly. That Kirby and Spence’s collar e is our pronotum, is proved
incontestibly by the circumstance, that, upon its separation from the
second segment, there is a spiracle. We observe this spiracle very
distinctly in the Diptera (PI. XIV. No. 1, f. 2, a), which shows U3
very evidently the limits of the prothorax, for which, without this
indication, we might look in vain, as the entire order is deficient in a
clear separation of the plates of the thorax. (See also PI. XIV.
No. 2, f. 2, a.) In the Hymenoptera and Lepidoptera, this spiracle
lies beneath the patagium, and, in the former (Vespa, Scolia, &c.),
appears as a distinct opening beneath the superior wing. This process,
which forms a sort of flap, may be called tile (Jtegula), for the organ
which Kirby and Spence have so called is the same with their patagium

THE THORAX.

(PL XII. No. 1 and 2 , d, d ; see § 77)» The first spiracle is constantly
the property of the prothorax throughout all the orders which have this
part free, and in a very flexible articulation with the second ; conse-
quently, in all the remaining orders, the first spiracle of the thorax
must necessarily belong to its first segment, and not, as would be the
case were the collar a portion of the mesothorax, to the second thoracic
segment.

3rdly. We may even adopt, as proofs in our favour, the reasons cited
by Kirby and Spence, in opposition to their own views. In the first
place, they say the collar lies directly over the prosternum (Chlorion),
and then moves freely with it ( Pompilus , Chrysis ), when the
collar has no prophragma (see lower down) ; but which is found
upon the dorsal piece lying behind it. Kirby and Spence have not
refuted all these reasons, but have considered them as rendered ineffec-
tive by their contrary reasons, which we have entirely refuted. It
clearly appears to us, therefore, that the term collar will, in future,
be useless, and instead of it, this part must be called by its more
appropriate name of pronotum.

In the order of the Lepidoptera , this pronotum approaches to the
shape of a collar, for in them it leans against the second segment, in
the form of a thin plate, and thus forms its commencement (PI. XII.
No. 1, f. 1, a ). Besides which, it is here called collar e by the describers
of Lepidoptera, particularly wherever it is covered with differently
coloured hair, or small scales. But even here it is the true represen-
tative of the pronotum .

§ 76.

The intermediate ring of the thorax, the mesothorax consists, in
its most developed state, of seven pieces, the three pairs of which are
so closely united, that each appears to form but one piece ; thence,
consequently, we have four chief pieces, which we distinguish as meso-
NOTUM, MESOSTERNUM, and the SCAPULAE.

The mesonotum (PL IX. &c. c, c, c. Kirby and Spence’s dor so-
lum and scutellum ), forms superiorly the corneous covering of the
mesothorax. It is generally of a quadrate shape ; it is convex on the
exterior and concave within, bent down laterally, and is here, chiefly,
in direct union with the remaining corneous plates. It is divided into
two parts, which are never distinctly separated, but merely indicated
upon the superficices. The anterior piece or true back (dorsolum of

PARTIAL ORISMOLOGY.

Kirby and Spence), generally exceeds the posterior piece in size. In the
orders with a free prothorax, this covers it, and it is only visible upon
the removal of the latter ; in the rest it occupies the whole central sur-
face of the back. In front, at its exterior angles, the corneous ribs of the
superior wings articulate, and two corneous ridges, originating at this
point and proceeding into the cavity of the thorax, serve for the inser-
tion of the muscles which move the wings. In the Hydrocanthari ,
the mesonotum is very small, and indicated only by a delicate corneous
transverse line (PL IX. No. 2, f. 7j c.) ; it is very large in the Melli-
JercE and Lepidoptera, as well as in the Diplera ; in the dragon flies,
(PL XI. No. 3, f. 1, 2, c, c.), it forms as an obliquely descending bent
plate, the anterior portion of the thorax in front of the wings, and
therefore does not represent the collar of the Hymenoptera and Diplera
(our pronotmn), as Kirby and Spence maintain. The posterior divi-
sion, the scutellum ( scutellum ), is here seated, as in all, between the
wings. This scutellum (PL XI. &c. c, c.), is, properly, no separated
part ; but, as we have already seen, a mere process of the mesonotum.
It is to be observed very distinctly in the Coleoptera, in which it
presents itself as a small triangular plate seated between the elytra
and the pronotum. In some genera ( Macraspis ), it attains conside-
rable size ; indeed in Tetyra and Chelyphus , it almost covers the
whole abdomen *. It always extends far backwards, between the
posterior wings ; and in many families, it completely covers the third
thoracic segment (PL XIII. No. 4 and 5, c, c. ; PL XIV. No. 1 and
2, c, c .) ; not unfrequently a strong membrane or even a peculiar cor-
neous ridge ( Cicada , P. XIII. No. 5, f. 1, d, d.) proceeds from the
side of the scutellum to the base of the superior wings, and thereby
strengthens their connection with the dorsal piece (PL XIII. No. 4,
f. 1, d, d). This ridge or membrane, Kirby and Spence call the
frenum. In many Coleoptera the scutellum appears to be deficient,
from its not displaying itself upon the superior surface between the
elytra (as in Copris ) ; but it is, nevertheless, present, although
covered by the elytra and pronotum. These have been called Esca-
tellati , wanting a scutellum.

It is not unusual to find other processes upon the scutellum, as spines
and teeth, and which are occasionally found in almost all the orders ( Psi -
lus Boscii , Stratiomys , Sargus, Reduvius ). But we more rarely observe

Compare Dalman, Analecta Entomol. p. 32, p. 2, B.

THE THORAX.

such excrescences upon the meson otum ( ClUellaria ). The prominences
upon the surface of the mesonotum (for example, in Cimbcx, Sir ex,
Tabanvs, Asilus, &c.) arise from the insertion of the muscles ; the
furrows which separate them correspond with similar ridges upon the
interior, which the bundles of muscles embrace. A great partition, of a
horny substance, separates superiorly the cavity of the second thoracic
segment from the first ; it descends from the upper side of the dorsal
piece, in greater or less distension, and likewise serves for the insertion
of the muscles of the back. Kirby and Spence call it prophragma.
At its superior edge the membrane is affixed, which unites the first and
second segments.

§ 77.

The scapulae are contiguous to the mesonotum (PI. IX., &c., d, d).
On each side, in front, close to the mesonotum, they assist to form the
articulating socket of the superior wings ( pteropega , Kirby and Spence),
and they here contract themselves, that they may pass into the cavities
of the prothorax in those orders which have a distinctly separated pro-
thorax, and with their opposite wing they pass down the sides of the
mesothoracic segment. They consequently fall into two divisions,
which may be distinguished as the anterior and posterior wings of the
scapulae ( ala scapulae anterior et posterior). Beneath and beyond the
posterior wings of the scapulae, in the Coleoptera, is found the spiracle
of the second thoracic segment ; it is entirely covered by it, which
explains why it has been hitherto overlooked. Straus- Durckheim dis-
covered it, and has distinctly shown its situation*. My attention being
thus drawn to it, I have fully convinced myself of its constant presence
in the Coleoptera , by numerous investigations. In the orders with an
unseparated prothorax, this part appears to diminish in compass as well
as in importance ; at least we never clearly discern a distinctly sepa-
rated scapula, but peculiar pieces, analogous by their situation, doubt-
lessly represent them, although with an altered function. As such we
consider the patagia, and tegulae of the Lepidoptera and Hymenoptera ;
they are both decidedly the same part, and are also seated precisely at
the same place, but differ in their mode of attachment, the tegula of
the Hymenoptera being affixed to the mesonotum above the wing, and
the patagium of the Lepidoptera beneath it, to that part which we

* Consid. Gen., PI. VII. fig. 6, II.

PARTIAL ORISMOLOGY.

consider as the analogue of the posterior wing of the scapula (see
PL XII. No. 1, f. 1 and 2, d ; No. 2, f. 2, d). In the Diptera, this
scale appears as a mere protuberance (PI. XIV. No. 1, d) in front of
the base of the wings ; thus also, by reason of its smallness in many of
the Hymenoptera ( punctum callosum ante alas of Fabricius) ; but in
these it is always a separate piece. That which has been called the
shoulders {humeri) in other Diptera, for example, in Myopa, is
certainly erroneous, for it is the analogue of the collare of the Hyme-
noptera, and the same as our pronotum (PI. XIV. No. 2, a). In all
the apterous genera, as well as in all those orders which display a closer
union of the several pieces of the thorax, the scapulae are not either to be
recognised as distinct pieces. In the Coleoptera and Orthoptera they
are never wanting ; but their separation into two parts, which we have
called their wings, is not always apparent.

The third piece, the mesosternum ( peristethium of Kirby and
Spence), i3, as well as the scapulae, divided into two parts ; but here
they are equal. It is directly opposite to the mesonotum, upon the
underside of the thoracic case, and includes one-half of the acetabula of
the intermediate legs. It is distinctly observed in all the orders; in
many ( Diptera , Hemiptera) it is not separated from the other pieces
by clearly defined limits, but merely indicated by furrows ; in others
(the Hymenoptera) , it attains considerable size (PI. XII. No. 2, f. 2
and 3, e, e), and in these extends upwards upon the sides of the
thoracic case, as high as the articulation of the superior wings. In the
Coleoptera and Orthoptera, which display considerable resemblance in
the conformation of their thorax, it is small, and frequently appears
but as a small prominent ridge between the intermediate legs ( Hydro -
philus, Gryllotalpa, PI. IX. No. 1, f. 8, e) ; in the former it is
sometimes even excavated for the reception of the dagger-shaped
process of the prosternum ( Elater , Buprestis, PL IX. No. 3, f. 5, e ;
Dyticus, PL IX. No. 2, f. 8)* This sternum is separated into two
equal halves by a central longitudinal division, which, however, is but
little apparent upon its superficies, and can be discovered only upon a
close inspection ( Buprestis , Dyticus, &c.).

§ 78.

The third and last segment of the thorax, the metathorax, resem-
bles the second, in being of a more united structure than the first.

THE THORAX.

which is to be ascribed chiefly to the circumstance of their having both
wings and legs attached to them, whereas the first has but legs alone ;
consequently greater compass was required for the reception of the
muscles of the wings, and which explains the reason of their much more
artificial construction. We likewise observe the fullest development in
the number and situation of the parts to occur here, also, in the Cole-
opter a, as was to be expected in the highest order. The third seg-
ment, likewise, consists of seven pieces, which are similar to those of the
second. The superior central piece, the metanotum (PI. IX., &c. f, f),
occupies the whole superior part of the metathorax ; it is generally an
oblong quadrangle, with the anterior angles advanced : it is frequently
hollowed in front. A somewhat arched partition ( mesophragma of
Kirby and Spence), which descends into the cavity of the thorax, sepa-
rates the cavity of the meso- from that of the metathorax, and serves
for the insertion of the muscles of the back, as well as of the legs. The
membrane which connects this segment with the preceding passes over
this partition, but which is, however, no longer apparent in the Hymen -
optera, and in all those orders wherein the corneous plates are attached
together. In general, the posterior edge of the scutellum projects
somewhat over the anterior margin of the metathorax ; it often ( Diptera
and Cicadaria ) conceals its centre — though rarely its entire surface
( Tabanus , Pi. XIV. No. 1. c; Chelyphus , Tetyra). Sometimes a
straight furrow, which, however, occasionally runs concentrically with
the scutellum, separates from the remainder an anterior portion of the
metathorax, which has been called postscutellum. In the saw-flies
( Tenthredonodea ) this portion, particularly laterally, very strongly
projects, and displays two small, very generally white, points, which
are called cenchri.

The posterior wings are placed at the anterior angles, and often
occupy the whole sides of the metathorax. This occurs through the
medium of a peculiar organisation, the description of which belongs to
the anatomical division ; thus much may stand here — the strong cor-
neous nervures are attached to the metathorax by articulation, and the
membrane is formally affixed to it, and is supported, upon the expansion
of the wing, by the horny plates contained within it.

A pergamenteous partition at the posterior margin, and called the
metaphragma, and which descends in a perpendicular direction,
bowing in its middle towards the abdomen, separates the latter from

g 2

PARTIAL ORISMOLOGY.

the thorax (PL XIV. No. 1, f. 2, h); there remains only a small space
below for the passage of the intestines, the organs of the nervous and
respiratory systems, and of the vessels, &c. In all insects with a
pedunculated abdomen ( abdomine petiolate), this partition is exposed,
and thus forms the covering of the truncated posterior portion of the
metathoracic segment ; it even seems to distend itself towards the
superior surface, and to terminate only at the above indicated furrow
of the metathorax, whereby this becomes a positive suture (PL XII.
No. 2, f. 1 and 2, Scolia and other Hymenoptera ).

Directly opposite to the metanotum, and precisely in the centre of
the under surface, we find the metasternum (PL IX., &c. g, g) ;
likewise very generally a quadrate, corneous plate, but which more
rarely takes the shape of a triangle, hexagon or octagon ( Hister ,
PL IX. No. 3, f. 12, g), and which helps to form anteriorly the aceta-
bula of the intermediate legs, and, posteriorly, those of the posterior
legs. It is sometimes perfectly fiat, sometimes slightly convex, and
sometimes distinctly ridged, and occasionally prolonged posteriorly into
a point ( Xiphus metasterni) ; and when thus, it projects over the
abdomen ( Hydrophilus ). It differs considerably in extent in Oryctes
(PL X. No. 2, f. 4, g) and Cetonia (the same. No. 1, f. 2, g) ; it
occupies nearly the whole pectus; sometimes, as in Hister (PL IX.
No. 3, f. 12, g), only the centre ; sometimes it is compressed into
a comparatively small compass by the coxce of the posterior legs ; it
is thus formed in Dyticus (PL IX. No. 2, f. 8, g). In many Coleop -
tera, for example, in the Lamellicornia , the meso-and meta-sternum are
so closely united, that it requires violence to effect a separation. In
others (for example, Buprestis , PL IX. No. 3, f. 5, g), the metasternum
consists of two halves, which are separated by a central longitudinal
suture, which internally forms a ridge.

The construction in the other orders differs materially from this
description of it in the beetles ; but in the Orthoptera very slightly.
In these, likewise, the metasternum is a clearly distinguishable, but
undivided plate, placed between the acetabula of the four posterior
legs (PI. XI. No. 2, f. 5, g). In the apterous genera, we do not
observe the meso- and meta-sternum to be divided into several pieces,
and they adhere tolerably closely to the original annular form of the
segments (see PI. XIII. No. 1 and 2, the thorax of the female Tengyra
and Myrmosa). In the Hymenoptera , the construction of the meta-

THE THORAX.

sternum closely approximates to the above description of that of the
beetles ; it is likewise seated between the acetabula of the posterior
legs, and appears as a distinct, but undivided plate, as in Scolia (PI. X.
No. 2, f. 2 and 3, g). In the Lepidoptera it takes the figure of a
semicircle, which lies in front of the coxae of the posterior legs, separates
them from those of the intermediate legs, and between them it projects,
with its obtuse ends, at the sides of the thorax (PL XIII. No. 4, f. 2, g).
It appears indicated in the same situation in the Diptera, but is not
separated, for in them all the parts of the thoracic segments are firmly
united. In the Hymenoptera, the metasternum merits particular atten-
tion, from its deviating from the structure of the other orders by pos-
sessing a spiracle peculiar to it, which is placed anteriorly upon its supe-
rior lateral margin (see PI. XII. No. 1 and 2, f. 1 and 2, ß). In the
Lepidoptera and Diptera, it is placed as in the other orders, between
the meso- and meta-thorax. Latreille, therefore, considers this portion
of the thorax as belonging to the abdomen, maintaining that no spira-
cles are to be found upon those segments of the thorax which are
provided with wings ; which assertion is, however, unfounded, as we
have seen. He thence concludes that the kälteres (see the end of this
section) of the Diptera cannot represent the posterior wings of the
other orders, because a spiracle is found upon the segment where they
are placed. But that this circumstance proves nothing will have
become self-evident.

Between the metanotum and the metasternum, two other horny
pieces are found on each side, which we, with Kirby and Spence,
distinguish as the pleura and parapleura. Straus calls them
Ischia, and distinguishes the former as the ischium primum ; the latter
as ischium secundum.

The pleura (PI. IX. No. 2, j, j) is contiguous to the metanotum,
and is united to it by a delicate membrane ; the membrane of the wing
proceeds from it, and this is attached in the same manner to the pleura
beneath, as it is affixed above to the metanotum. It is a small, longi-
tudinal, scarcely observable plate, which, in repose, is covered by the
elytra, and is not perceptible until they are removed. In the Orthop~
tera (for example, Gryllotalpa3 PI. XI. No. 1, f. 8, j), the pleura is
much extended, and posteriorly it is drawn somewhat downwards, so
that it extends to the acetabula of the posterior coxae. In the Libellu -
lina, it is almost supplanted by the very large parapleuroe, and in these

PARTIAL ORISMOLOGY.

insects, from the two pieces being united posteriorly, it appears as a
small triangle* beneath the cavity where the abdomen is affixed (PL XI.
No. 3, f. 3, j). In the Hymenoptera , Lepidoptera , Dipt er a, and
Hemiptera, the pleurae and parapleurse are not distinctly separated,
but form a single, undivided pleura, which often, besides, is strictly
united with either the metanotum or metasternum, or indeed with both
together.

The PARAPLEURSE (PI. IX., &c. h, h) of the Coleoptera, as well as
of the other orders in which it is distinctly found, lies between the meta-
sternum and the pleura. In general, they are larger than the latter,
lie nearer the under side of the body, and adapt themselves in shape to
the space left by the other plates. They are very frequently quadrate
(PL XI. No. 1, f. 6, h ; No. 2, f. 10), with sometimes parallel, and
sometimes diverging sides (PL IX. No. 3, f. 6, h) ; in other cases, three-
sided (PL IX. No. 2, f. 8, h) ; and very large and trapezoida lin Gryl -
lotalpa (PL XI. No. 1, f. 8, h), as well as mLibellula (No. 3, f. 2, h).
In these they are prolonged posteriorly, make a bend at the angle of
the thorax, and in the centre of the metasternum they unite in one
piece (PL XI. No. 3, f. 2 and 3, h). In the other orders, the pleurae
and parapleurse are not separated, but form one single plate. In the
Diptera peculiar interest attaches to it, from the remarkable kälteres
being seated there. They originate frequently in a stalk {stipes), as fine
as a hair, from the anterior margin of the pleurae, and shortly terminate
in sometimes a round, and at others a compressed knob {capitulum).
They frequently stand quite free, and are then called naked {kälteres
nudi), or else they are covered by one or two delicate scales {squama),
which are attached to the mesotliorax, and extend from its margin
upwards to the scutellum, and are doubtlessly analogous to the previ-
ously described frenum of the other orders. We have not yet attained
any very distinct idea of the import of the halteres ; but this is not the
place to introduce an investigation of the subject ; we refer to the
proper place, in the second and third divisions, for much that applies
to it.

* Without this somewhat forced view, it would be scarcely possible to explain the
construction of the thorax in the Libellula. We must imagine the feet to be drawn
forwards, whilst the back and the wings project posteriorly, whereby the parapleurse are
advanced in front of the pleuroe, and these united posteriorly into one piece.

THE THORAX.

§ 78 *.

After having thus explained the construction of the thorax in the
different orders of insects, it remains for us now to notice the works
of other naturalists upon the same subject, and to indicate the differ-
ence of the results of their investigations.

The earliest work of this kind is that of Chabrier ; it appeared as
the introduction to his treatise upon the flight of insects *, which was
presented to the academy of Paris on the 28th of February, 1820. He
here, with Latreille, divides the thorax into prothorax, mesothorax,
and metathorax, but unites the two last divisions as tronc alifere.
Each of these segments is subdivided into the upper, or dorsal, and
under, or pectoral, part ; called also cotique pectorale, from which
processes, the entosternum, spring inwards. Between both, upon the
metathorax, are found the clavicules thoraciques ; and upon the meso-
thorax, the plaques fulcr ales. The partitions, or phragmae, he describes
as pros- and post-dorsum ; and he calls the scutellum, bascule. He
consequently adopts as many pieces as we have described : the annexed
table will show more distinctly their conformity.

Chabrier was succeeded by Audouin in a similar investigation, in
which, however, the chief object was the particular description of the
sternum. This was also presented to the academy, and a report of it
was given by Cuvier, in the Annales Generales de Physique, tom. vii.
(1821 f). He has here adopted, in general, the same parts; but each
single one is divided into several pieces, with particular names, although
such pieces are never found separated from each other. It may also
be objected to Audouin’s performance, that he has not distinguished
the several dorsal and pectoral plates of the three segments by distinct
names, but has merely called them terga and pectora. We cannot,
therefore, retain his nomenclature. But Audouin admits of three seg-
ments, which he calls pro -, meso -, and meta-thorax ; each consists of
tergum, episternum, sternum, and entothorax ; to which are added, in
the prothorax, the trochantinus and the peritrema ; in the meso-
thorax, the peritrema and paraptera ; and in the metathorax, the
parapterum only. Each tergum consists of the prcescutum, or the
anterior deflexed margin, which, in the mesonotum, becomes the pro-

* Essay sur le Vol. des Insectes. Paris, 1832, 4to.

t Audouin himself published the paper in the Annales des Sciences Naturelles, tom. i.
p. 97, and p. 416.

PARTIAL ORISMOLOGY.

phragma, and, in the metanotum, the mesophragma ; the scutum, the
disc of each dorsal plate ; the scutellum , or the posterior margin ; and
the 'post scutellum, the posterior deflexed margin, which, in the meso-
notum, becomes sometimes the mesophragma, or, upon the metanotum,
it forms itself into the metaphragma. Upon the prothorax, the epister-
num and the epimerum form our omium : the former is the exterior
surface ; the latter the interior surface, directed towards the acetabula.
Where the shoulder- piece is not free, they then belong to the pronotum,
and form the lateral parts. The trochantinus by no means belongs to
the thoracic case, but to the coxae (§ 168, II. 4) ; the same applies to
the peritrema, which forms the corneous ring of the spiracle. The
entothorax is what we shall describe below (§ 165) as the processus
internus sterni ; it is in strict union with the sternal plate, and is
never free or separated from it. I do not distinctly know what the
parapterum is ; probably a lateral process of the dorsal plate. I have
never found a free portion in that situation. In the mesothorax, the
episternum and epimerum are our scapulae: but upon the metathorax,
the parapleurae.

After Audouin, Straus -Durckheim * andMacleayf both produced,
nearly about the same time, a work upon the thorax of insects : the
description of the latter adheres very closely to that of Audouin.
He uses the same names and adopts the same parts ; but in his sub-
division of them, he goes still further, without there being a sufficient
reason for it. For example, the sternal plates of the meso- and meta-
thorax, he says, consist each of eight pieces, although in no insect with
which I am acquainted is there the least indication of any other sepa-
ration than the above- adduced division into two halves.

Straus-Durckheim pursues in his description of the thorax, as well
as throughout his work, a peculiar path, without troubling himself in
the least about the labours of his predecessors. He divides the whole
thorax into corselet and thorax , the latter comprising that portion
which bears the wings ; this is again divided into prothorax (our
mesothorax) and metathorax. The corselet consists of the bouclier ,
our pronotum ; the two pubis, the rotule, Audouin’s trochantinus,
and the sternum antcrieure. He distinguishes in his prothorax the
ecusson , our mesonotum, the clavicule anterieure, Audouin’s para-

* Consid. Gen. sur l’Anat. comp, des Ani. Articul. Par. 1828, 4to. p. 76, &c.
f Zoological Journal, Vol. v, (1830), No. 18, p. 145.

THE THORAX.

pterum, a part unknown to me ; the iles or ilialiques, our scapula, and
the sternum moyen , our mesosternum. His metathorax consists of the
clipeus, our metanotum ; the clavicule posterieure, a part which I also
could not find, and which I consider to be either a mere process of the
metanotum, or one of the joint pieces at the root of the wing ; the two
ischion , our pleura and parapleura ; and lastly, the sternum posterieure ,
our metasternum. He also takes notice of the corneous rings of the
spiracles, as parts of the thorax, and which are seated in the articu-
latory membrane of it : he calls them cadres.

The description is good and praiseworthy, like all the works of the
skilful Straus ; but the French names which he adopts must give place
to the partially older Greek ones.

In a comparative view of the number of the thoracic pieces named
by different authors, we find that Knoch has twelve, Kirby and
Spence, twenty, Chabrier and myself, eighteen, Audouin, thirty-six,
of which Macieay makes fifty-two, by the separation of each dorsal
plate into four pieces ; and Straus-Durckheim, twenty- two, because,
besides the eighteen described ones, he adopts a clavicule to both the
meso- and meta-notum.

The annexed table gives a precise comparative view of the nomen-
clature of the several writers.

COMPARATIVE VIEW OF THE NOMENCLATURE OF THE SEVERAL AUTHORS,

FOR THE PARTS OF THE THORAX AND THEIR PROCESSES.

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THE THORAX.

Organs of Motion upon the Thorax.

A. The Wings,

§ 79.

The organs of motion are of two kinds, either wings [alee), or legs
(pedes').

The wings, generally four in number, are placed, as we have already
seen, upon the second and third segments of the thorax, and united to
it by means of joints or an articulatory membrane. They always
consist of a double membrane, which is traversed by corneous veins or
ribs (neurae, vence , costae ), and by means of which they are held
expanded. This, their general structure, suffers a variety of modifi-
cations in the different orders, which may be comprehensively repre-
sented in the following table : —

I. Four wings.

1 . All of similar structure and membranous :

a. Of equal size. Neuroptera (with the exception of

the families of the May-flies), as well as the families

% of the Libellulina and Termitina.

b. Of unequal size. Hymenoptera, Lepidoptera, Phryga-

neodea, the remaining JDictyotoptera, and many Hemi-

ptera homoptera.

2. The anterior corneous or pergamentaceous, the posterior

membranous :

a. The anterior corneous.

a. Entirely corneous, Coleoptera.

b. Half corneous, half membranous, Hemiptera
heteropiera.

b. The anterior pergamentaceous. Ortkopiera, and some

Hemiptera homoptera.

II. Two membranous wings. Dip ter a.

The general observations which we purpose here introducing upon
the wings, will merely refer to their number, situation, form, and
clothing. The inquiries into their structure, import, and purpose,
belong to other divisions of this work, and will, consequently, remain
untouched upon here.

Very little is to be said upon their number ; sometimes, and indeed,
in certain genera and species of almost every order, they are wholly

PARTIAL ORISMOLOGY.

deficient, more frequently only the posterior pair : thus, in all the
Diptera , some Cimices and many Coleoptera, but in the majority of
cases there are four distinct wings present. The deficiency of the first
pair has never been observed.

Their situation is more certain than their number, for wherever we
find wings, they are attached to the second and third segments of the
thorax, and, indeed, at its superior exterior dorsal edges, close to where
the dorsal and lateral plates adjoin. If we find no wings here, we can
speedily convince ourselves whether the insect does not possess them,
or whether it has lost them by some casualty, which is not of unfre-
quent occurrence. We speedily detect such a mutilation by the
presence of the joint sockets and a portion of the wings. Apterous
insects entirely want the sockets.

Before we proceed to the consideration of the form of the wings, we
must remind ourselves of the differences indicated in the preceding
table, as they exercise an important influence upon the form of the
wing. The horny or pergamentaceous anterior wings, namely, differ
so considerably in their whole structure from the membranous poste-
rior wings, that they have been very justly considered as different
organs, and have been called the wing cases (Elytra). The whilst
the beetle, or any other insect which possesses elytra, reposes, they lie
parallel beside each other upon the back and abdomen, and thus conceal
not only the posterior wings, but also very generally the whole abdo-
dem. It is from this function that they derive their name.

We distinguish in the elytra their base (basis), the part by which
they are attached to the thorax, and the opposite extremity, the apex :
then the margins and the inner ones, which lie contiguous, and which
we call the suture. Should the posterior wings be wanting, the union
of the elytra is generally so strict, that it requires great force to sepa-
rate them ,* such elytra are called connate ( Elytra connata). The
angles are thus distinguished, the superior exterior one, as shoulder
angle (angulus humeralis), the interior one, as the angulus scutel-
laris.

The most usual form of the elytra is the longitudinal extended, we
might almost say oblong, did not the exterior bowed margin very
generally join the sutural margin, a ta pointed angle, or by its rounding
very gradually pass into it. The upper surface is convex, the under
concave ; the exterior margin is very generally deflexed, and often
forms on the exterior a sharp edge.

THE THORAX.

The following are the chief differences of the elytra : —

Truncated (truncata), are such elytra which are a little shorter
than the abdomen.

Abbreviated ( abbreviata ), when they cover but a little more
than its half.

Dimidiate ( dimidiata ), when exactly half as long as the abdomen.

Short (brevissima) , when they are not half the length of the abdo-
men.

Mutilated ( mutilata ), are those which cover only a portion of
the abdomen, yet more than the half, but less than the apex ; they are,
consequently, longer than the short and shorter than the truncated
elytra ( Aptinas ).

Fastigiate ( fastigiata ), are such which extend a little beyond the
apex of the abdomen.

Entire (Integra), when they are exactly the length of the abdo-
men, and display no distinguishing peculiarity of form.

Auriculate ( auriculata ), are those which have at their humeral
angle a peculiar, free appendage ( Lycus , Cassida .)

Subulate ( subulata), are those which gradually decrease towards
their apex, and which leave, both upon the sutural and exterior margins,
a portion of the abdomen uncovered (Necydalis, Fabr.)

Elongate ( elongata ), are those which are much longer than the
abdomen.

Dehiscent ( dehiscentia ), when the suture is somewhat divergent
at the apex.

Ampliate (ampliata, s. amplificata), when the edge of the exte-
rior margin is very high and prominent ( Dyticus latissimus.)

Complicant ( complicantia ), when one elytra extends over the
other, and partially covers it (Meloe).

According to their inclination we distinguish

Even (plana) elytra, the whole superficies of which is upon one
plane.

Deflexed (i deflexa ), when the vicinity of the suture lies higher
than the exterior margin ; sometimes they rise into a pyramid, called

Turreted ( iurrita ), or they are very convex in the centre, viz.
Gibbous (gibba).

Both the elytra together are called the sheath or covering ( coleop -
tera), and each single one a wing case (elytrum).

The differences of surface have been already sufficiently described at

PARTIAL O RI SM O LOGY.

section 19, for almost all the differences of form there named are to
be found in elytra. The same applies to the differences of margin,
but with greater limitation.

Their clothing, also, is so variously different, that scarcely any
description of it is found upon the insect body, which does not also
occur upon the elytra ; we, therefore, here again refer to the General
Orismology.

The hemelytra, or half corneous wing-cases of the Hemiptera
heteroptera, have most qualities in common with the entirely horny
elytra. In the majority we can distinguish four divisions separated
by furrows, the first three of which are horny, but the fourth forms
the membranous portion. The first, the nail, ( Clavus, PL XV. f. 1 . a),
is a longitudinal almost parallelly sided piece, situated at the interior
margin, contiguous to the scutellum, and, in repose, partially passing its
sharp edge beneath it ; close to this, upon the exterior, lies the hem-
el ytrum (PL XV. f. 1, b ), which is the largest of all the divisions,
and forms a triangular horny piece, which enters the mesothorax with
its anterior acute angle. The appendix (PL XV. f. 1. c), which is
frequently wanting, follows the hemel ytrum ; it is likewise a trian-
gular, but much smaller, and often right angular horny plate, the
right angle of which is contiguous to the exterior margin of the hem-
elytra, so that the hypothenuse is turned towards the inner margin. The
fourth and last division is attached to this, and which is called the
membrane ( membrana , PL XV. f. 1. d ), from its membranous quality.
It is generally of a rhomboidal form, with obtuse angles, or it is ovate,
but more rarely forming a somewhat reversed half moon. It likewise
consists, like all wings and wing-cases, of a superior and inferior layer,
between which horny ribs pass, and distend it.

The pergamentaceous cases, called tegmina, differ from the true
elytra, by being less firm in their substance, and from the true wings, by
their greater strength. They are situated at the same place with the
elytra and hemelytra, and they approach nearer to the latter in their
structure, but most closely to the true membranous wing. For,
although in the hemelytra the ribs and veins are more apparent, yet
in the tegmina they are so clearly developed, that they are no longer
subject to doubt. Lower, in the anatomy, we shall find that the elytra
also possess such veins, but which, from the thickness of their substance,
do not become prominent.

In form, the tegmina are subject to greater differences than the

THE THORAX.

elytra or hemelytra ; for sometimes they are shorter than the body,
broad, ovate ( Gryllotalpa ) ; sometimes as long, with parallel sides,
rounded ( Blatta ) ; sometimes longer, very slender, acute, and narrowed
at the base ( Gryllas, Fabr.) ; and sometimes very wide, large, and ellip-
tical {Mantis). By means of the veins originating from a main stem,
which furcate from the very base, they are divided into three prin-
cipal areas; the first of which, seated upon the exterior margin (PL XV.
f. 2, a), is in general the narrowest, and towards the apex of the
tegmina contracts gradually to a point ; it is also usually of a harder
substance than the following. This second piece (PI. XV. f. 2, b)
lies contiguous to the former, and is separated from it by the before-
mentioned chief vein ; it is the largest of the three areas, embraces the
majority of the ramifications of the veins, becomes gradually wider
towards the apex of the wing, and consists of a softer membrane than
the marginal area. The third, or sutural area (PI. XV. f. 2, c), lies
inwardly beyond the second, and it is also harder than the central area ;
in many families it forms the superior dorsal covering, while the two
other areas fall down upon the sides of the body ( Gryllodea , Locustaria) .
It varies considerably in figure ; it, like the marginal area, is sometimes
a very pointed isosceles triangle ( Gryllodea ) ; sometimes, as in the hem-
elytra, a space surrounding the scutellum ( Achetaria ) ; it also some-
times appears to be wanting, or not distinctly separated from the cen-
tral area ( Mantodea ).

There seems likewise to be some difference in the ramification of the
horny veins throughout these three areas ; in the marginal one they are
small, broad, multitudinously divided veins, which appear to spread
from two or three radiating main branches. In the central area, the
large stems spread more parallelly from the inner side of the chief stem,
which separates them ; the transverse veins also run parallel, and thus
divide the whole area into small squares. In the inner area, lastly, the
veins are most delicate, and ramify variously on all sides, whereby an
irregular reticulation is formed.

§ 80.

The mere membranous wings (alee) distinctly differ from the pre-
ceding organs by their transparency, and purely membranous nature.
In respect to their situation and general function, they perfectly agree
with the former ; but the wings are exclusively organs of flight, while

PARTIAL ORIS MO LOGY.

the different kinds of elytra have the additional purpose of covering
the soft upper part of the abdomen. Therefore all insects provided
with wings only are entirely inclosed in a hard case, and, although
they possess wings, are equally unprovided with a protection against
exterior influences, as those genera and species which have no wings.

The observations we are about to make upon the wings will refer to
their exterior perceptible construction, and their different forms and
clothing. The investigation into their progressive conformation, their
internal coherence, their functions, &c., belong to other divisions, and
will be treated upon in the proper place.

In outward appearance, the wings present themselves as flexible, but
firm, dry membranes, which are traversed by various horny ribs. These
ribs ( costcB ), or more properly veins (nervte), as they are, in fact,
vessels, but incorrectly called nerves ( nervce ), arise all from the roots
of the wing, and through their main branches, of which we usually
observe two or three, they are connected with the thorax by articulation.
The first and most exterior of these veins is called the marginal rib
(i costa marginalis , ‘PI. XV. a, a), or, by pre-eminence, the rib (costa),
which forms its anterior margin when expanded, and extends from
the base to the apex. Jurine, who made use of particular names to indi-
cate the veins of the wings of the Hymenoptera, calls it radius ; and a
horny expansion of it in its course, which is particularly distinct in this
order, but which is also observable in others, he calls the point of the
wing (punctum, or carpus) ; but Latreille, and Kirby and Spence call it
stigma (PI. XV. f. 4, ß). The second vein originates close to the first,
and distinguishes itself from the rest, like the former, by its superior
robustness. Its course also is in a direct line towards the apex, but it
gradually diverges from the marginal vein ; so that the portion of the
wing enclosed by it, takes the form of a triangle. Kirby and Spence call
this the postcosta (PI. XV. f. b, b , b) ; Jurine, cubitus ; and Latreille,
ncrvus internus . It also ultimately attains the apex of the wing. It is
seldom simple ; in the majority of cases it divides itself into branches,
so that the main stem ceases before it attains the disc of the wing ; but
the branches extend from the separation, either continuing simply to
the end of the wing, or again ramifying. By means of these ramifica-
tions, a varied net-work is produced upon the disc of the wing, the
reticulations of which are tolerably constant in the several orders,
families and genera, and is therefore of importance for the determina-
tion and distinction of the groups. The spaces enclosed by these veins

THE THORAX.

are called areolets ( areolce ), or cells ( cellule , Jurine) ; and those
lying close to the marginal rib are called marginal areolets ( areola
marginales, PL XV. d, d) ; Jurine’s, cellule radiales ; those succeeding
to them, and formed by the postcosta and its branches, submarginal
areolets ( areolce submarginales, PI. XV. e, e) ; cellule cubitales of
Jurine. The transverse veins which branch from the longitudinal
nervures of the main stems, are called the connecting veins ( vena
anastomosis), or nervi recurrentes of Jurine. The areolets seated
at the end of the wing, and, sometimes not quite closed, are called
imperfect ( areolce imperfecta , PI. XV. f f), or cellulce incom-
plete of Jurine. The appended cell ( cellula appendicea ) of the
same author is a small, almost triangular areolet, situated at the apex
of the wing, which is formed by the furcate division of the vein spring-
ing from the stigma (in many genera of the Tenthredonodea ; for
example, Perga, &c.).

The space behind the second principal vein of the wing is its third
and last chief areolet, which, in many cases (Hymenoptera) , is ante-
riorly limited by a peculiar, slight vein, originating near the second
principal one ; and this areolet extends to about the middle of the
margin of the posterior wing. Several other veins and areolets (nervi
et cellulce brachiales, Jurine) are found within this space, which, as
they do not vary much in large groups, are consequently of less
importance for the determination of genera.

In the membranous wings we also find the same distribution into
three chief areolets which we have already indicated in the tegmina,
and we here distinguish them, with Kirby, as the marginal areolet
( area costalis sive marginalis) , central areolet ( area discoidalis s.
intermedia), and posterior areolet (area atialis s. posterior ). In
repose, during which the wings lie parallely upon the body, the poste-
rior areolet passes beneath the central one, turning upon its limitary
vein, like a door upon its hinge. In those orders, however, in which we
meet with elytra, or an analogous structure, the inferior wings are folded
in several directions. Thus, in the beetles, the whole apex of the wing
is very generally folded from the stigma back towards the base, or the
whole wing, from this point, folds itself like a fan ( Forficula ), or this
plication originates from the base of the wing, according to the direction
of the radiating veins ( Orthoptera ).

The preceding general description treats chiefly of the anterior wings;

PARTIAL ORISMOLOGY.

but it will equally apply to the posterior ones, when they are of the same
size and quality as the former (see the table, § 79). Where the poste-
rior wings differ in form from the anterior, they are in general smaller
— often, however, broader, if not longer. It is chiefly in the Orthoptera
that we observe this more significant size of the posterior wings ; in
these they are sometimes even longer than the anterior, and extend
beyond them ( Gryllotalpa) ; it is the same in some beetles with short
elytra ( Necydalis , Atractocerus) . In general, however, the true wings
of an Order are perfectly uniform in structure, although their veins
ramify differently, and, this also applies more generally to the pos-
terior wings, which less distinctly show the above-described separation
into three principal areolets, although, upon a careful inspection, these
would not be found deficient in them.

The following are the most important orismological definitions of the
wings: —

The anterior wings ( alee anteriores) are those attached to the
second thoracic segment; they are also called superior ( al . supe-
riores) from their covering the posterior ones in repose; or, the first
( primaries ) from their preceding the others in flight. The posterior
wings have had, from opposite reasons, opposite names applied to them,
as al. posteriores , al. inferiores , and al. seeundarice. In each wing we
distinguish, as the anterior margin ( margo anterior ), or exterior
margin ( margo externus ), that margin which, in flight, lies in the
direction of the head; that opposed to it as the inner margin (m.
internus) ; the third, generally taking the direction of an obtuse angle,
with regard to its situation as to the others, is called the posterior
margin (m. posterior). The angles formed by these margins at their
point of contact, receive the following names : — the anterior angle
( angulus anterior) is that at the apex of the wing, formed by the ante-
rior and posterior margins ; the posterior angle is that formed by
the contact of the posterior and interior margins. We have already
made mention of the humeral and scutellar angles.

The general outline of the wings is distinguished according to its
form; the following terms are used to express them: — falcate
( faleatee , PI. XV. f. 12) are wings whose anterior margin forms a circle
bending outwards, and their posterior margin is also directed forwards
(many Lepidoptera).

Tailed ( caudatce , PI. XV. f. 13) are those which have a long and

THE THORAX.

narrow appendage extending from the internal margin. This form is
found chiefly in the posterior wings of the butterflies (Pap. Machaon ,
Podalirius, &c.).

Digitate (digitata, PI. XV. f. 14) is a wing, which has its other-
wise undivided surface indented with deep incisions between the ribs
or veins (Orneodes).

Besides these outlines, which are peculiar to the wings, we likewise
find in them the majority of the differences mentioned in § 18.

The same applies to the differences of margin ; we therefore refer
to § 20.

The surface of the true wings is subjected to but few changes ; in
general it is a smooth skin, with here and there some hair spread over
it (in many Diptera , for example, Psychoda). In one order, however,
(the Lepidoptera) , the general law prevails for their being clothed with
flattened scales (alee squamosce).

The situation of the wings in repose is much more various in pecu-
liarities. We proceed to the consideration of these differences, and
thereby form a conclusion to the investigation we have here made upon
these organs.

Even (alee plance), are those wings which, in a state of repose,
preserve the same extension as when in motion.

Opposed to them are the folded wings (plicated). By this term
we understand such as are longitudinally folded in repose, like a fan,
and expand only during flight into a uniform surface (Orthoptera) .
We consider such wings as re-folded (replicatce) , when their apex
falls back upon the base.

Convoluted wings (al. convoluted) , are such which embrace the
body from above downwards, and enclose it as in a tube ( Cr ambus).

Incumbent (incumbentes), when, lying parallely upon each other,
they cover the abdomen above (Tenthredo).

Crossed (cruciatce), are those incumbent wings which pass over
each other only at their apex (many Bees, the hemelytra of the Hemi-
ptera heteroptera) .

Horizontal (horizontales), whose direction is in the same plane
with that of the body. The reverse of these are the erect wings
(erected), whose line of direction is perpendicular to the plane of the
body (Papilio).

Extended (extensce), form also in their direction a right angle with
the body, but lie in the same plane with it ; from these we must dis-

h 2

100

PARTIAL ORISMOLOGY.

tinguish the open wings (patentes) by the angle which they form with
the axis of the body, being at least of 45° ( Tabanus, Musca, &c.). The
erect-open wings (erectce patentes) do not lie in the same plane with
the body, but cut it at an angle of less than 45° (some Lepidoptera , for
example, Hesperia).

Connivent ( conniventes ), are such wings which, in repose, perfectly
unite with each other at their corresponding margins ( Papilio ) ;
divaricated (divaricates) , are such which only partially cover each
other (Agrion).

Deflexed (deflexce), are such which, with their internal margin,
meet at an acute angle, and so cover the body (many Noctuce) ; from
them must be distinguished the reversed wings (reverses) by this,
that the anterior margin of the posterior wing projects beyond the
same part of the anterior wing ( Gastrophaga alnifolia) ; this is also
often the case in the open wings.

b. The Legs.

§ 81.

The other chief organs of motion, the legs (pedes), are distinguished
from the wings in a multitude of ways, in form and number, as well as
in their function.

In number, they exceed that of the wings by one-half ; for although
we never observe more than four wings, we constantly find, in perfect
insects, six legs. These six legs are placed in pairs upon the lower
part of each of the three segments of the thorax, and consist of many
joints, to the observation of which we now pass.

We have already become acquainted with the ace tabula (ace-
tabula) upon the segments or plates of the breast, for the reception
of the legs.

I. These cavities receive pieces formed exactly to their dimensions,
frequently conical, or more longitudinal and rounded, called the hips
(coxce, PI. XVI. f. 1, a). Surrounded and enclosed by a corneous
substance, it has, only at each of its opposed ends, an opening for the
passage of the muscles which unite it to the surrounding parts. This
typical form of structure is somewhat modified by the closer or looser
union of the coxae with the thorax ; so that it appears sometimes as a
cone truncated at its apex, and then attached to the thorax by the
whole of its basal surface ( Diptera , Lepidoptera, Hymenoptera, &c.) ;
and sometimes moves itself freely in a proportionate cavity of the

THE THORAX.

101

thorax, to which it is affixed by a single small spot (many Coleoptera) ;
and sometimes, lastly, it displays itself more flattened, in which case
it is affixed to the thorax by a firmer and closer union, which admits
of no free motion (for example, the posterior coxae of Dyticus, Bu-
prestis, &c.). In this last case, frequently also in the first, the
coxae appear to belong more strictly to the thorax than to the legs, as
they stand in much more intimate connection with the former than with
the latter ; but their very general free motion speaks strongly against
the adoption of this opinion.

II. A much smaller corneous piece, the trochanter (PL XVI.
f. 1, b), stands in moveable connection with the coxa. The form of
this part is subject to many changes ; we sometimes find it quite
annular, with surrounding, equally high sides ; sometimes compressed
and obliquely truncated, or prolonged into a lateral point ( Carabus ,
Dyticus). This form is found chiefly among the beetles; in other
orders (the Diptera , for example) it has very generally the annular
form. In these orders, the articulation of the coxae consists only of a
firm membrane ; but in the former, ball-joints appear to be fitted to
corresponding sockets, whereby the strength of the union is very much
increased.

III. The trochanter is succeeded by the thigh (femur, PL XVI.
f. 1, c), which is the largest joint of the leg. It is generally of a cylin-
drical, but not always equally thick, frequently knobby or clavate,
form. It is very often much longer than the two first joints toge-
ther ; in general also longer than the following, but always thicker and
more robust. Besides this roundish form, we also observe angular, pris-
matic, parallelopipedal, flat, very much compressed, and provided with
a longitudinal furrow, or even globose and elliptical forms. Its union
with the trochanter is sometimes very close, at others looser. We meet
with its firm conjunction in the Coleoptera. In these the motion of
the thigh appears to be very limited, and in general the trochanter
moves in the articulation upon the coxae, when the thigh is touched ;
it is different in the Diptera , in which the freer union of both admits of
greater motion. The upper surface of the thigh is like that of the coxa
and trochanter, generally smooth ; but its margins are not rarely armed,
sometimes with solitary spines, sometimes with hair, or with long cilia.
Some have broad lobate appendages ( Trachusa lobata, Mantis oratorio).
We do not usually observe such processes upon the two first joints, for
coxae armed with a spine belong to the rarer exceptions ; these we

102

PARTIAL ORISMOLOGY.

observe among some of the Ichneumons {Ich. melanogonus, Grav. ;
Pimpla mesocentra, Grav.)

IV. The fourth joint of the leg is the shin {tibia, PI. XVI. f. 1, d.)
But in the same way as the thigh is united to the hip through the
medium of the trochanter, so is the shin connected with the thigh, viz. by
ginglymus, but in a reversed direction, for whilst in the former articu-
lation the shanks are directed upwards, in the latter it is the apex.
With respect to its form, it is very generally as long as the thigh, and
it is equally often thinner and more slightly framed. Notwithstanding
which, we observe more differences in the tibia than in the thigh ; it is
found conical, tubular, triangular, quadrangular, compressed either
partially or entirely, leaf-shaped, uneven and rough. It is not unfre-
quently that we perceive them armed or clothed with spines, either
solitary or placed in rows, with very long hair, teeth, fringe {tib.
fimbriatce), and setee. Indeed they occur more frequently upon the
shank than upon the thigh. In form, however, it is very much
regulated by that of the thigh, and its structure appears to agree as
intimately as is compatible with the preformed figure of that joint.
For example, should the thigh be conical, the shank forms a bow,
which fits closely to the cone ( Chalcis ), or if the thigh be convex, the
shank then forms a corresponding inflection. The same is the case in
raptorious legs {Mantis). At the end of the shin, and around the
cavities, wherein the following joint articulates, in general we observe
some spines, which are usually called spurs or terminal spines
{Calcaria, Spicula , PI. XVI. f. 1. 8, 8.) They are indeed most fre-
quently mere processes of the horny substance, but they are sometimes
articulated, and have a free motion at the will of the insect {Mantis).
In this case they form a species of pincers {Hylobius Abietis), which
assists the insect in climbing.

V. It is to the shin that the last division of the leg, the foot {tarsus,
PI. XVI. f. 1, e.) is attached. It consists of a series of consecutive
joints, the first of which is generally the largest, and the following
gradually decrease until the last, which is again longer than the one by
which it is preceded. The last is armed with claws and appendages at
its termination. The connection of the first with the shin is also by
ginglymus, and indeed the fork of its two shanks point upwards,
whereas the joints of the foot itself are connected so together that they
form but one surface in their union. The cavity of each joint is placed
near the upper surface, often in its very centre, and its anterior margin
is produced beyond it. By means of this arrangement, the joints

THE THORAX.

103

can only bend upwards, but they are allowed in many cases a slight
inflection downwards.

The number of the foot-joints varies from 1 to 5. As these numbers
are tolerably uniform in the several families, and as many insects closely
allied to them possess the same number of foot-joints, they have been
used in forming divisions in the several orders, which are thus distin-
guished.

Pentamerous (jpentamera) , when all the feet have five joints.
Crypto-pentamerous (crypto-pentamera) , are those which truly
possess five joints, but in which the penultimate is so small that it
can be perceived only upon the most rigid inspection, and by means of
a lens ( Cerambyx ). Kirby and Spence call this joint the arthrium.

Heteromerous (heteromera) , when the four anterior legs have,
five, but the two posterior ones only four joints.

Tetramerous ( tetramera ), when there are four joints to all the
feet. The Crypto-letramerous appear to have but three joints,
the penultimate being very small (Coccinella) .

Trtmerous ( trimera ), feet with three joints.

Dimerous (dimer a), feet with two joints. And lastly,

Monomerous ( monomera), when the foot has but one joint.

The different forms of the whole foot as well as of the individual
joints are shown at § 83.

§ 82.

Forms of the Legs.

The most simple form of the legs, in which all the joints have the
usual construction, and no peculiar qualities are displayed even by the
feet, is distinguished by the name of cursorious legs ( pedes cursorii ),
even in those cases where the insect is anything but a runner, and but
slowly moves about. The Carahi are the chief representatives of this
form.

Ambulatory (ambulator ii), are those whose feet have a broad hairy
sole (Lamia).

Gressorious (gressorii), are those whose anterior pair is imperfectly
developed, whilst the rest are formed upon the type of the cursorious
legs. Sometimes the foot is wholly wanting (Ateuchus, Lonchophorus,
PI. XVI. f. 2) ; sometimes all its joints are small and imperfect ( Vanessa ,
Hipparchia, PI. XVI. f. 3).

Natatorious (natatorii), are the legs of insects which live entirely,

104

PARTIAL ORISMOLOGY.

or partially, in the water ; their shins and feet are broad, compressed,
and fringed on each side with long hair (. Dyticus , Naucoris , Notonecta)

Saltatorious ( Saltatorii , PI. XVI. f. 5), are those which have very
thick posterior thighs, by means of which the insect is enabled to make
wide leaps ( Haltica , Orchestes).

Raptorius ( raptorii , PI. XVI. f. 6), are those whose shins and
feet in repose turn back upon the thigh, and often pass into it like a
knife within its handle ( Mantis , Syrtis, Nepa, Ranatra), This struc-
ture is found only in the anterior legs, and somewhat justifies their
being called hands, which Kirby and Spence proposed, from the
raptorious legs serving to seize the prey with.

Fossorious ( fossorii , PL XVI. f. 7), are those legs whose tibiae, and
frequently feet, are very broad, and resemble a hand, serving the
insect to dig holes and passages in the earth ( Clivina , Heterocerus,
Gryllotalpa.

§ 83.

Forms of the Joints.

We must here, at the conclusion of our notice of the legs, observe the
differences of the structure of their joints, although we have touched
upon many of their forms in the preceding descriptions.

1. Hip. — Besides the above noticed difference, we must distin-
guish immoveable hips, which are affixed to the thorax (for example
those of Dyticus , PI. IX. No. 2, f. 8), as fixed (fixce), and the moveable
ones, which turn in the socket, as free ( liberce , PI. XII. No. 5,
f. 2 and 3). These last might, particularly in reference to their form,
be called joint balls (capita femorum), as the whole hip can in
fact be nothing else than a moveable thigh ball. Hips, beneath which
there is a curled lock of hair, are called flocculate ( fioccatce , for
example Andrena, PI. XVI. f. 8).

2. Trochanter. — Kirby and Spence call it fulcrant ( fulcrans )
when it is continued for a space along the thigh, thereby strengthening
its union ( Carabus , PI. XVI. f. 9). This joint occasionally consists
of two rings (for example, Pimpla, PL XVI. f. 10), and it is then
called dimerous ( dimerus ), but it is most usually monomerous
( monomerus ), having but one joint.

3. Thigh. — We have fully distinguished its differences above.

4. Shin. — We add the following differences to those in § 81. IV.

Policate ( policata ) is when it is produced inside into a short bent

spine.

THE THORAX.

105

Palmate ( palmata , PI. XVI. f. 2), when the whole shin is com-
pressed, and upon its exterior margin there are short but strong teeth
(. Hister , Ateuchus).

Foliaceous ( foliacea , PI. XVI. f. 11), when, instead of its usual
tubular form, the shin is entirely or partially extended into a thin
horny plate ( Lygceus , Coreus) ; or Clypeate ( clypeata , PI XVI.
f. 12), when the enlargement is only upon one side, and is slightly
convex (the males of some Crabro’s).

Scopate ( scopacea , PI. XVI. f. 13), is a broad shin, densely covered
with short hair (many bees). This, considered as a distinct organ,
Kirby and Spence call a brush ( sarothrum ).

5. Foot. — Of all the divisions of the leg, the joints of the feet are
subjected to the greatest varieties of form. Most frequently cylindrical,
by the narrowing of the base they gradually pass into the conical shape,
but even these feet are somewhat flattened beneath, and thus form a kind
of sole (for example in Carabus). This kind of narrow sole has no
other distinction than that it is limited by two small ridges, which in
front are produced into two small spines (PI. XVI. f. 14). These
kind of feet are peculiar to those insects which run upon rough and
especially horizontal surfaces (the Carabidea) ; others, which move
upon perpendicular and moving objects, have flat broad joints, which
are provided with a peculiar clasping apparatus. Such flattened joints
are sometimes, cordate (PI. XVI. f. 15), triangular (f. 16), quadrate
(f. 17), simple, or emarginate in front (f. 15), sometimes more deeply
divided and bilobate (PI. XVI. f. 18). This last form is in the
majority of cases peculiar to the penultimate joint only (for example
in the Cerambycina , as Callidium violaceum ) ,* in other cases several
are divided, for example, the three first in JBrachycerus , the third and
fourth in Lycus, &c. The individual joints are nearly 'equally long
and broad, but it is not unusual for the first to be longer than the
following, and it is then called, particularly when in its general
structure it diverges from the following (as in the bees), metatarsus.
The remaining equal joints then form the toe ( digitus ) or the finger
( dactylus ) ; they are individually called the phalanges, and not,
as some writers presume, fingers and toes. All insects are conse-
quently one-toed ( monodactyla ), the genus Xya. 111. ( Tridactylus ,
Latr.*) only having actually two equally long toes (PI. XVI. f. 19).

* See Charpentier, Horae Entomologicae. Vrat. 1825. 4to. p. 84 Tab.

106

PARTIAL ORISMOLOGY.

If the foot-joints are broader than long, and assume a lunate form,
and are so closely attached together that the first large one embraces
all the following within its deep concavity, and the whole foot appears
to form but one disc, it is called patella. The males of the genus
Dyticus display this structure (PI. XVI. f. 23. a, b), the underside is
then thickly beset with compact hair, and between which several unequal
cups, patelluljE, are placed which serve as organs of attachment. We
pass to this structure by the enlarged feet ( tarsi amplificati ) ; these
consist of heart-shaped joints, which are also clothed beneath with brushes
and feathers. But in these we distinctly discern each individual joint ;
indeed sometimes they are not all so, but only some upon some pairs of
legs, for example the first three joints in the anterior pair of the male
Cicindelce , (PI. XVI. f. 20) ; the four first i nCarabus (f. 21) ; and but
seldom only one joint is dilated (in HydropJiilus ). Modern entomologists
(Zimmerman, for instance #), call a thus widened foot palma, and
the single joints patellae, which is scarcely admissible from the
above indicated definition of these words.

Compressed feet ( tarsi compressi ) stand in direct opposition to
the depressed or flattened feet ( tarsi depressi ). We find them most
fully formed among the bees. In these, namely, the first joint is most
closely affixed to the shin, and appears to be but a division of it,
whereas it properly belongs to the foot. The cause of this structure is
to be found in their economy ; for covered with hair, as is also the shin
in this case, it serves to carry the pollen of flowers. Such a hairy shin,
in conjunction with the first joint of the foot, is called brush
(sarothrum) as we mentioned above. The second kind of compressed
feet is peculiar to the water beetles (PI. XVI. f. 4), but here its super-
ficies is smooth, and the margin only occupied with a fringe of stiff setae.

The last joint of the foot is particularly distinguished from the rest by
having at its end two slightly bent moveable hooks, which with it form
a claw {unguis), by help of which insects move upon smooth surfaces,
and indeed are enabled to creep up perpendicular walls. The hooks
( unguiculi ) of these claws are either equal ( Carabus, f. 24), unequal
{Anisoplia fructicola, f. 25), or round, compressed, and in this case of
immense size ( Rutela , f. 26) very generally they are simple (ung^
simplices ), but also bifid (ung. bifidi or fissi, Meloe , Tetraonyx ,
PI. XVI. f. 27), sometimes armed beneath with one ( Melolontha ,

* Sec his Monographic der Zabroidcn. Berlin, 1831. 8vo.

THE THORAX.

107

PI. XVI. f. 29), or several ( Hippobosca , PI. XVI. f. 29), teeth
( unguic . dentati ), and at others, the under-edge is toothed like a saw
( unguic . serrati , or denticulate. Calathus , Cistela, &c. PI. XVI. f. 30).

Between these two hooks of the terminal joint, we perceive in some
insects a second smaller claw,called the spurious claw {pseudonychia),
but by Nitzsch empodium. Among the beetles, we find this structure
in Lucanus (PI. XVI. f. 31). This claw perfectly agrees with the
larger one in its conformation, and consists, therefore similarly to this,
of a stalk-like basal-joint, at the end of which there are two little
hooks. In the Hymenoptera , Diptera, and some families of other
orders, we find instead of them, soft, gently convex, oblong, mem-
branous cushions, the soles ( plantuce ) or climbing cushions ( arolia ,
Nitzsch, PI. XVI. f. 32). These attach like sucking-cups, and there-
fore the insects provided with them (for example the Diptera?) can run
lightly and securely upon vacillating objects. We seldom observe
spurious claws and cushions together ( Laphria , PI. XVI. f. 33) ,* still,
more seldom, are both wanting as well as the larger claws ( Xenos ,
PI. XVI. f. 34).

The underside of the foot, or sole ( planta ) has, when very narrow,
nothing to distinguish it. But if the foot is depressed, the sole has a
peculiar clothing, which has been called foot-cushion ( pulvillus ). It
consists very generally of short and stiff hair {Lamia, PI. XVI. f. 35),
more rarely of radiating plumes ( Zabrus , PL XVI. f. 36), occasionally of
true fleshy cushions ( Xenos , PI. XVI. f. 34). Some genera ( Timarcha)
display minute cup-shaped hollows in the sole, which is then called
spongy [pi. spongiosa , PI. XVI. f. 37). In the majority of the first
adduced instances, the margin also is covered with short hair.

]08

PARTIAL ORISMOLOGY.

III. — The Abdomen.

§ 84.

The third and last chief division of the body of an insect bears the
general name of abdomen. Notwithstanding its being very variable in
form, it does not exhibit an equal difference of structure, but consists
of several consecutive horny rings or segments, in some cases merely
following upon, in others, retractile within each other. These rings
vary much in number, but never exceed nine. Upon consideration, we
shall remember that the body of all caterpillars and undeveloped insects
consists of thirteen segments (§ 53). Of these, one constitutes the
head, three the thorax, and, consequently, nine remain for the abdomen.
These, however, are not always present ; frequently, several appear
united in one ; and, more frequently, the last are so completely covered
by the preceding, as wholly to escape observation upon a superficial
examination. Sometimes, also, the back presents more divisions than
the belly; indeed, in Carabus we observe nine distinct dorsal divisions,
whereas, we can distinguish in the venter but five. The belly very
generally presents one less than the back. We observe, also, a
difference of number in the sexes ; for, in many Hymenoptera *, the
males have seven and the females but six segments. These segments
are either simple horny rings, or else each consists of a superior and
inferior half ring, which are connected together at the sides by means
of a delicate membrane ; sometimes a longer or shorter free process of
the superior half segment projects over this point of union, thus
covering this delicate part from all exterior injury. In the Coleoptera,
and, in general, in such insects as are provided with hard superior
wings, this structure is not to be perceived, but the soft uniting
membrane lies exposed, and even the horny substance of the superior
half segment is very small and soft, from the very natural cause of the
hard elytra supplying the place of all other modes of protection. In
these orders, therefore, the ventral portion of the segments acquire

All the Aculeate Hymenoplera. — Tr.

THE ABDOMEN.

109

additional and proportional consistency and firmness. This part is
called the belly ( venter ) in contradistinction to the upper superficies
corresponding with the breast, which is named the back ( dorsum ).

The union between the several superior and inferior segments is
effected in precisely the same way as between the upper and under
half segments, by means of a soft membrane. This connecting
membrane is perceptible only upon the back, and only in those
instances where the back is protected by hard superior wings or wing-
cases ; in all the rest, the posterior margin of each segment laps
over the commencement of the succeeding one, thus covering and
protecting the soft uniting membrane. If we observe the abdomen in
its most distended state, for example, in a gravid female, it appears as
a large membranous bag, covered above and beneath with equally broad
parallel, transversely round and convex horny plates ; or, if the horny
substance be considered as its fundamental material, it may be
compared to a horny bladder divided by parallel membranous girdles,
and which are also separated laterally by similar membranous stripes
running at right angles with the transverse parallels.

Precisely at the points of intersection of the membranous longitudinal
and transverse stripes, there is placed on each side a small opening
surrounded by a callous margin, and which is called the air-hole,
stigma, or spiracle ( stigma , spiracula), which is the opening to
the respiratory organs ramifying throughout the body. In the usually
contracted state of the abdomen, the natural situation of these
spiracles is beneath the horny processes of the superior half segment ;
but in the Coleoptera with corneous elytra, they lie upon the upper
surface of the abdomen close to the sides, and are equally protected
by those organs. These spiracles, consequently, are in every instance
most carefully protected from external injuries.

Other openings which lead to the intestines and the organs of
generation we shall notice lower down.

The uniting membrane of the horny plates Kirby and Spence
call pulmonarium, from the circumstance of its containing the com-
mencement of the respiratory organs ; but its chief purpose being
evidently the union of the several horny rings, it must also justly
thence be called uniting skin (conjunctiva) . In descriptive entomo-
logy, however, it is of but little importance, as it is never visible, being
always covered either by the processes of the horny segments or bv the
wing-cases.

PARTIAL ORISMOLOGY.

With respect to the general form of the abdomen, it varies so
extremely, that we can scarcely suggest a universal type of construction.
It is sometimes ovate, longitudinal or cylindrical, sometimes compressed
and angular or broad and flat ; but its transverse section may always be
readily reduced to the form of a rectangular triangle, the base of which
lies above, the apex pointing downwards. It is not possible to give a
more definite determination to this triangle, for its sides are sometimes
straight, sometimes, chiefly the upper one, convex, sometimes the
opposite sides form an apparent semicircle, occasionally they bend
inwards or outwards, &c. &c.

The form of the abdomen depends much upon the mode of its
attachment to the thorax. In the majority of cases, for instance,
in the Coleoptera, Orthoptera, Dictyotoptera , Hemiptera, and in
many families of the other orders, the abdomen is conical, that is to
say, it commences with a broad base and gradually decreases towards
its apex ; when this broad base is united by its whole circumference to
the metathorax, the abdomen is called sessile. But even a perfectly
conical abdomen, the base of which is sharply truncated, is sometimes
connected with the metathorax by means only of a small portion of its
margin {Vespa). This mode of union between both parts of the body is
most perceptible in those insects whose first abdominal segment has the
form of a thin tube, which, towards its apex, distends more or less
trumpet-shaped. The succeeding broader and larger segments are
united to the first in the same way as among themselves, and by this
means the either ovate, conical, compressed, falcate, flat, or longitudinal
abdomen appears as if, like the leaf of a tree, it was supported by
a distinct stalk, whence it has been called by entomologists petiolated
{ab. petiolatum). The tubular first segment itself is called the
pedicle ( petiolus ). It is not always a direct tube, but occasionally
swollen into knots {pet. nodosus), or distended upwards into a thin
scale {pet. squamatus). If the second abdominal segment be of greater
compass than the following, so that its margin stands freely out,
and the succeeding segment completely received within it, the abdomen
is then called campanulate {ab. campanulatum, for example Zethus).
But if, on the contrary, the abdomen be constricted at its commencement,
and not perfectly petiolated, as in the Butterflies and most Diptera,
it is called coarctate {ab. coarctatum).

In many instances, all or individual segments of the abdomen have
peculiar processes, which are found sometimes at their sides, and which

THE ABDOMEN.

Ill

project as lappets (ab. lobatum), or rise in thorns or spines from the
surface of the plates. If a solitary large horn be placed upon the
centre of the venter, it is called hastate (ab. hastaturn ) ; horned
(ab. cornutum), on the contrary, when it proceeds from the back ;
marginate (ab. marginatum) , when its sides project in sharp ridges,
(Coreus marginatus') ; or winged (ab. alatum), when the projection of
the margin is very considerable (Coreus quadratus, many Tingis ).
These differences of margin are generally found only in such insects
whose superior wings form horny wing-cases; consequently only among
the Coleoptera , although among these but rarely, Orthoptera and
Hemiptera , and among the latter most frequently.

§85.

We must now turn our attention to the abdominal appendages.

The appendages of the abdomen may be classed into three large
groups, according to whether they belong to the anus or the sexual
organs, or to neither one nor the other.

The anus is a round opening near the upper side of the last abdominal
segment, and is in but few instances provided with peculiar appendages,
but lies within the last abdominal segment which closes the rectum
with its two halves. In these cases, the sexual organs open into the
cavity formed by the last segment, and are similarly covered by it. It
might not, therefore, be inappropriate to call this cavity with its opening
by the name applied to the analogous construction in Birds, the cloaca.
Kirby and Spence propose podex as the name for the superior flap, and
for the lower one, hypopygium. In those instances in which the anus
is not closed by the flaps of the last segment of the abdomen, we
observe peculiar thick processes which close its aperture like the prongs
of tongs ; they are sometimes hooked, and are then called unci
(Locusia, Gryllus ).

The appendages attached to the sexual organs are more remarkable
both in shape and function.

With respect to those upon the anal segment of male insects,
they are generally less peculiar than those of females. Both sexes
are deficient in these appendages when the last segment forms a
cloaca ; on the contrary, we find in those which have a free sexual
opening a sort of tongs close to the male organ, between the prongs of
which the penis is found, either lying freely exserted, or else retracted

112

PARTIAL ORISMOLOGY.

within the abdomen. The hooks of such tongs are of very different
construction. In Dolichopus* they are lamellate, and armed with
hooks at their end ; lanceolate with an obtuse apex in the Libellulce,
narrow, round, and spinose upon their inner margin in many Noctucs ;
simple, almost straight, but suddenly curved at their extremity in
Locusta ; short, thick, cylindrical, with lobate appendages in Laphria
and Asilus. The last segment frequently takes a very different shape
in consequence of these appendages, in Tipula it is clavate, in Myopa,
conical, cheliform in Panorpa, &c.

The appendages of the sexual organs of female insects consist almost
exclusively of more or less prominent ovipositors, by the aid of which
they more easily deposit their eggs in appropriate places. We distin-
guish their following chief varieties.

1. The sting ( aculeus , PI. XXIII. f. 5 — 18) is a thin, delicate,
finely-pointed tube, consisting of several valves, and which sometimes
projects from ( Sirex ) and is sometimes withdrawn within the abdomen
( Vespa ). This sting is never a simple horny spine, but always
consists of two or three pieces, the largest of which is barbed at
its extremity, and is longitudinally channelled (PI. XXIII. f. 7, c, and
f. 12) to receive the rest (the same, f. 7> d, d ). It possesses, besides,
two lateral valves ( valvulce , the same, f. 6, a, a), between which the
sting lies like a sword in its case. If the sting project beyond
the abdomen, they accompany it, but only in those insects in which it
lies freely exserted. In the bees and wasps, which use it also as
an offensive weapon, the valves remain within the abdomen during
its use.

Latreille calls the freely projecting ovipositor the borer ( terebra ).

2. The tube ( tubulus , PI. XXIV. f. 15) is a mere continuation of
the abdomen, which occurs in Chrysis and many Diptera , viz. the
house-fly. It consists of several cylindrical joints, which are united
by a soft membrane, and are retractile within each other, like the joints
of a telescope. This kind of ovipositor is found only in insects which
have but few abdominal segments, whence it is not improbable that
the joints of the tube are nothing else than segments of the abdomen
itself.

3. The sheath ( vagina , PL XXIV. f. 10 ) consist of two long, convex
continuations of the abdomen, generally inclining upwards, which, when

Meigen. Zweif., Vol. iv. PI. XXXVI. f. 21

THE ABDOMEN.

113

placed together, exactly correspond, and form a single organ — the
ovipositor. Between them lies the female sexual aperture, and the
eggs are laid encompassed by them. ( Locusta .)

Besides the above-named organs, several other forms are observed at
the apex of the abdomen, which neither belong to the anus, nor can be
considered as standing in connection with the sexual organs. They
bear the general name of tail ( cauda ) or caudal appendages
( Appendices caudales ) : as such we may consider

The forceps (Jbrcipes, PL XIV. f. 8), two toothed cheliform
hooks, which move in opposition to each other, in the earwig.
( Forficula .)

The fork ( furca , PL XIV. f. 9) a continuation of the lower
portion of the terminal segment, which is directed forwards, and is
furcate, by means of which the insect springs upwards. ( Podura ,
Smynthurus .)

The styles ( styli , PL XIV. f. 10), two short exarticulate processes,
close to the anus in Staphylinus.

The cerci ( cerci , PL XIV. f. 11), likewise short, lanceolate, and
generally flattened and g/„iculate appendages at the sides of the anus.
( Blatta .)

The threads ( fila , PL XIV. f. 12), longer or shorter articulate
cylindrical processes of the last segment, which grow gradually thinner.
( Acheta , Ephemera , Lepisma.)

The bristles {setce, PL XIV. f. 13) are such appendages when
exarticulate and simple. ( Machilis .)

The siphonets (.y iphunculi, PI. XIV. f. 14) are the hollow processes
upon the upper side of the penultimate segment in the plant-lice (Aphis),
whence the sweet juice exudes which the ants seek so eagerly.

SECOND SECTION.

ANATOMY.

§ 86.

The examination of the exterior form of the body is succeeded by the
investigation of its internal construction. This branch of natural science
is distinguished by the name of Anatomy (derived from ava.Tepv£iv, to
cut up ) ; but the portion of it which treats of the interior structure of
insects might be appropriately called Entomotomy (derived from eWo-
pov, bisect , and repvEiv, to cut).

As it was not our object in the preceding chapter to explain the
mode whereby the different parts of the body stand mutually con-
nected, but which combination and connection is of importance to the
formation of the complex organism we have already examined exter-
nally, it is therefore incumbent upon us, in this section, to display the
fundamental parts, or, as it were, the keys of this entire organism, and
what the different materials are which must necessarily unite to con-
stitute the organic body we have just treated of. The information
which will be conveyed in this section will consequently be richer in
its results towards a knowledge of the life of insects in general, as it
will materially tend to show how far the differences of form are influ-
enced by differences of structure, and what their mutual relations are.
We shall nevertheless restrict ourselves, even in this section, to a mere
description of forms, but principally of the internal parts, and conse-
quently of their structure, reserving the reply to all questions upon
the importance of each individual organ, its function, and sphere of
action, to the next ensuing section.

But, before we pass on to the contemplation of these new objects, a
few general remarks will not be inapposite to determine the natural
succession of the investigations we are about to institute.

ANATOMY.

115

§ 87.

Experience has instructed us that every organism is not only tran-
sitory in its duration, but that it also requires the assimilation of fresh
matter, if it is to be preserved from perishing immediately after its
appearance. To meet this necessity nature has furnished every organic
body with two different sets of organs, which are called systems, the
one of which provides for the preservation of the individual by means
of nutriment, and is thence called the nutrimbntal system, and
the other for the continuance of its resemblance, or kind, and which is
called the re- productive system. Both systems, therefore, are the
essential peculiarity of every organic body, and without them no
organism can be imagined.

§ 88.

Indeed, the very lowest organic bodies, plants, display no other
organs than such as belong to these two systems; but the animal
destined to a higher grade of organisation adds to the phenomena of
vegetable life two new proofs of its vitality, and which must be treated
as the results of a greater freedom of nature. This liberty displays
itself at once in its independence of its original place of abode, by the
powrer it possesses of constantly changing it ; in fact, the power of
locomotion is the first and principal peculiarity of the animal, and this
power also qualifies the second phenomenon peculiar to animal life.
If, namely, the animal is to make an advantageous use of the freedom
it derives from its power of locomotion, and if it be to be secured
against all the disadvantages consequent upon this power, it must
necessarily possess faculties which apprise it of the nature of its situa-
tion, and these it has received in the organs of sensation. Both,
consequently, the organs of locomotion and sensation, are peculiar to
the animal, and wholly wanting to the plant, whilst the organs of
nutriment and re-production are common to both.

§ 89.

And as the organs of nutriment and re-production are first observed
in the plant, and as the whole vegetable kingdom displays no higher
development of life, they are distinguished as vegetative organs, and
their circle of action the vegetative sphere. Whereas the organs
of locomotion and sensation, as the exclusive peculiarities of the animal,

i 2

116

ANATOMY.

have received the name of animal organs, and their compass of action
the ANIMAL SPHERE.

§ 90.

The greater development or separation into several distinct organs,
and the more complex structure of each, are the phenomena gradually-
displayed in the progressive ennoblement of the animal kingdom, com-
mencing at the most simple conditions of animal existence. Insects
maintain in every respect a central situation in this series ; their
organs, therefore, will not display to us a very artificial structure, nor
will their combination be very complex. But we shall find the above
indicated four chief differences, which are dependent upon the vital
phenomena of the organism, sufficiently distinctly exhibited in them.
Now, as the several organs of each individual system not only aim at
one object in their functions, but also display considerable conformity
in their structure, it will be suitable to regulate the arrangement of our
present investigation by their differences, whence we derive the follow-
ing themes : —

I. Investigation of the vegetative system and its organs. These are,

A. The organs of nutriment, consisting of —

The general integument. As this in insects is a horny case, to
which the organs of locomotion are attached, its description
must be classed with the consideration of the animal organs,
it being but the passive agent of motion. Therefore of

a. The intestinal canal with its appendages, as digestive

organs ;

b. The heart and blood vessees, as organs of circulation ;

c. The air vessels, as respiratory organs.

B. The organs of re-production ; consisting of —

a. The female organs of re-production, and

b. The male organs.

II. Investigation of the animal system and its organs.

A. Organs of locomotion : —

a. Passive organs of motion ; here the exterior integument

as analogous to the osseous system.

b. Active organs, the muscles.

B. Organs of sensation : —

a. The brain;

b. The nervous system in general ;

VEGETATIVE ORGANS.

117

c. The nervous system of the digestive organs ;

d. The organs of the senses.

We consequently commence our description with the vegetative
organs, as being the inferior ; and thence proceed to the survey of the
animal organs, as the superior ones. But we do not wish by this
arrangement to imply that the lowest insects have no organs of locomo-
tion and sensation, but that in them both these organs, and also par-
tially the vegetative ones, are not quite so perfectly developed and
completely combined as in the higher orders, and from the circumstance
of this difference the latter stand higher and the former lower in
the system. And by these expressions, as well as by the synonymous
ones, of more or less perfect, we would indicate that the structure
of the former is more complex, artificial, and various than the groups
characterised as standing lower and less perfect. But each group is
perfect in its kind.

FIRST SUBSECTION.

VEGETATIVE ORGANS.

§ 91.

The organs of the vegetative sphere are, as it were, transmitted
from the plant to the animal ; it will therefore be not unimportant if
we can prove that their fundamental texture displays a vegetable
origin.

The plant commences its existence in the form of a cell ; cell is
added to cell, and the entire vegetable is but a congeries of small cells,
with here and there long delicate tubes interspersed, forming, as it
were, free passages between them. All the organs of vegetables consist
of these two forms, consequently the nutrimental and re-productive
organs must display a similar, or at least an analogous, structure, if
they are to prove themselves of vegetable origin. Nothing, in fact, is
more astonishing than the confirmation of this law ; for cells, which in
animals become small vesicles or larger bladders, and tubes, constitute
the various forms of the vegetative organs. A vesicle, the egg, is the

118

ANATOMY.

origin of animal existence ; vesicles distend themselves, and become
cases ; they link themselves in a series, and form vessels ; and thus, by
degrees, each vegetative organ is formed from the vegetable original.

We will examine this more closely in the individual organs.

§ 92.

The intestinal canal is a tube which originated from the elonga-
tion of one or the connection of several bladders. This is proved not
only by its form in the lower animals, but also from its being in many,
likewise in the larvae of insects, a mere blind sack, consequently a
bladder open only in front. In animals of a higher grade, in which it
consists of several divisions separated by constrictions, it is very easily
imagined as consisting of the union of several bladders.

The same holds good of the vessels : for example, the chief vessel of
insects, namely, the large dorsal vessel, so evidently displays a cellular
construction that we may not consistently doubt its original growth
from bladders.

The very name of the air-tubes announces their form. It must, how-
ever, strike as important that the air-vessels of insects have so deceptive
a resemblance to those of plants that everybody must immediately
admit of their analogous structure.

The vegetable origin of the nutrimental organs is thus evidently
proved.

§ 93.

It is not more difficult to show the same in the organs of reproduc-
tion. These, namely, very much more distinctly display their vesicular
origin. The ovary of the female is a large bladder, containing many
smaller ones, the eggs. The oviduct is an elongation of this large
bladder ; the uterus is another distension of it, and the vagina ano-
ther elongation : other incidental appendages of the above parts display
more or less distinctly a vesicular form.

It is the same in the male organs. The testes have not uncommonly
the shape of a bladder ( Lamellicornia ), or else they are long convoluted
tubes, which we know to be but modifications of bladders ; the vasa
deferentia are elongations of these bladders; the vesica seminalis
another distension of it, and the ductus ejaculatorius another and
its final constriction.

Thus the sexual organs are a still more evident repetition of the
vesicular form, they being always closed at one end at least.

THE ORGANS OF NUTRITION.

119

§ 94.

We shall show in full detail, at its proper place, that the character
of the organs of the animal sphere differs wholly from the vesicular
character of the vegetative organs by the integral solidity of each indi-
vidual part.

FIRST CHAPTER.

OF THE ORGANS OF NUTRITION.

1. THE INTESTINAL CANAL AND ITS APPENDAGES.

§ 95.

The intestinal canal ( tractus intestinorum) is the internal tube,
extending from the mouth, appropriated to the reception and trans-
formation of the nutriment. It has in general a second aperture opposed
to the first, the anus, through which the indigestible unassimilating
remains of the food are rejected. The instances in which such an anal
aperture is deficient are very rare among insects, and occur only among
larvae and maggots, but never in the imago.

This tubular structure of the intestinal canal is subject to con-
siderable modification from distension and constriction, by means of
which it is separated into several divisions, which have very justly
received different names, from their functions being dissimilar. Be-
sides these separations of the intestinal canal itself, we observe
peculiar processes and appendages, which originate from it, or
which, as perfectly independent parts, merely open into it. Their
variety and modifications produce relations which yield multifarious
differences in form and structure, and which link certain groups of
insects more closely together by their complete uniformity, whereas
they separate others, in which such a similarity of arrangement is not
observed, more distinctly from each other, and thus more fully corro-
borate the dissimilitude expressed in their exterior conformation by this
difference of their internal structure.

120

ANATOMY.

§ 96.

The entire intestinal canal consists of three skins, or layers of mem-
brane.

The innermost membrane (PL XVII. f. 1), which may be considered
as a continuation of the exterior epidermis, is very smooth and texture-
less, and only sometimes longitudinally folded, and armed above with
horny lines, ridges, or teeth (PI. XVII. f. 2. 5 — 7)* It is particularly
distinct in the pharynx, crop, and proventriculus, the horny teeth of the
latter being formed by it. This internal membrane is most apparent
in insects with hard cases, as the Coleoptera and Orthoptera, whereas
it is not so evident in the haustellate Diptera and Lepidoplera. From
the proventriculus it forms a very delicate perfectly uniform covering,
and generally occupies less compass than the other intestinal mem-
branes. We here call it the epidermis, it being its analogue, or pro-
perly, the mucous membrane, as it corresponds with the tunica mucosa
of the superior animals.

The second layer, which we call with Straus the proper skin ( mem -
brana propria ), is white and smooth, and usually thin, but sometimes
thicker and spongy, most frequently without any texture, but occa-
sionally figured ( Hydrophilus , PL XVII. f. 2.). This membrane,
which Ramdohr treats as a layer formed of transuded chyle, is pecu-
liar to the intestinal canal, and is not found in the other internal organs ;
it may therefore be considered as a continuation of the second layer of
the exterior integument, of which we shall treat below. Indeed, the
space between the mucous membrane and this peculiar skin, which is
very considerable in the stomach, and particularly in caterpillars, is
often occupied by a flocky web, formed of transuded chyme, and this
may have misled Ramdohr in his idea of it. According to Straus, horny
prominences are sometimes observed in this intermediate skin, parti-
cularly in the vicinity of the stomach, which might be considered as
absorbing pores, but which Straus, perhaps more correctly, treats as
glands, and they are therefore called gastral glands (glandulce gastriccz).
I have observed these organs only upon the inner surface of the mus-
cular membrane, but particularly distinct in Hydrophilus , in which
insect the long cylindrical stomach is completely and regularly covered
with such glands, which consist of a transparent case inclosing a darker
kernel (PL XVII. f. 3.).

The third layer (PL XVII. f. 3 and 4.) is a compact, firm, fleshy

THE ORGANS OF NUTRITION.

121

muscular membrane ( tunica muscularis), in which distinct longitudinal
and transverse vessels can be discerned, and it lies closely upon the
preceding. These vessels, which are sometimes completely reticulated,
sometimes furcate separately and rejoin in the same manner *, are gene-
rally of a uniform size, but occasionally the transverse ones are stouter,
the others more delicate and slender, but also more numerous and
closer together, so much so that tlieir distinct threads may be consi-
dered as the separated bundles of muscles t. This muscular membrane
is not equally observable in all parts of the intestinal canal : it is very
obvious in the pharynx, stomach, and colon ; but it vanishes almost
entirely in the crop or craw.

§ 97.

The situation of the intestinal canal is the same in all insects. It
always commences as a cylindrical, and chiefly narrow tube at the
somewhat wider cavity of the mouth, and proceeds in a direct line
through the head and thorax. It takes the same direction in all
insects which have a long and at the same time thin body (e-g. Pimpla,
Tipula, Agrioii). In these cases, however, the intestinal canal is of
the same length as the body, and only in some of the broad-
bellied ones, for example, the long bugs ( Gerris , Emesa, Ranatra), it
makes a small curve before its termination, so that it becomes about
half as long again as the body. But if the creature be thick bodied,
and the cavity of the abdomen is distended on all sides, the intes-
tinal canal becomes longer than the body, and makes convolutions
within the cavity of the abdomen ; but it always passes in a direct line
through the head and thorax.

These convolutions of the intestinal canal are kept in their proper
situation by the multitudinous branches of the air-vessels which spread
about them ; indeed, this reticulation of the air-vessels is so delicate
and firm that it not only makes it difficult to represent the intestinal
canal with all its appendages (which besides is closely enveloped in the
fatty mass) in its full extension, but makes a perfect separation of all
these air-vessels absolutely impossible. We never find in insects a peri-
toneum, which in the higher animals retains the intestines in their
place, but its purpose is supplied by these air-vessels.

* Ramdohr, Ueber die Verdanungswerkzeugc der Insccten Halle, 1811. PI. XIV.
f. 4, from Pompilus Viaticus.

•f The same PI. XVII. f. 2., from the fauces of the larva of the Ant-lion.

322

ANATOMY

§ 98.

The length of the intestinal canal increases with its convolutions ; or
these rather are but the consequences of its extension. We very fre-
quently find the intestinal canal twice the length of the body ; indeed so
often is this the case that it may be considered as the most usual struc-
ture. A nutrimental canal of this extent is called moderately long ;
such an intestine makes from one to three convolutions, according to
their size. The long intestine ( Chrysomela , Cimex) makes also two
or three, but larger convolutions, and is from three to five times the
length of the body. The intestine is, lastly, very long in the Lamelli-
co? nia, in which it is from seven to eight times as long as the body,
and makes many folds in the cavity of the abdomen.

But these proportions refer only to the perfect insect, for the majority
of larvae, namely those with a perfect metamorphosis, have a nutri-
mental canal of the same length, or at most of twice the length of the
body. This short intestine increases in length in every distinct period
of its life ; but some instances occur in which this gut becomes shorter
during the metamorphoses, namely, in the Diptera, the larvae of which
have a very long and much convoluted intestine *.

§ 99.

No general law regulating the various length of the intestinal canal
has yet been discovered ; in insects, in particular, it appears exposed
to much irregularity. It is not however improbable, from all hitherto
instituted investigations, that herbivorous insects have a longer and
more distended intestine, and that those which feed upon animal
matter have it shorter and narrower. We, however, find a decided
exception in the vegetable devouring Orthoptera (e. g. Gryllus, Lo -
custa ), their intestine being not much longer than their body, but at
the same time very broad. We perceive greater uniformity, if not in
length yet in structure, in the different orders of insects, and this law
we shall observe to prevail still more forcibly in the still smaller groups.

§ 100.

We will now pass from this general description of the entire intes-
tinal canal to the examination of its different divisions. We can there-

* Ramdohr, PL XIX. f. 1 and 2.

THE ORGANS OF NUTRITION.

123

fore make a primary separation of it into its several divisions and
its APPENDAGES.

The divisions of the intestinal canal are, the pharynx, the (eso-
phagus, the craw, the proventriculus, the stomach or ventri-
culus, the duodenum, the ilium, the ccecum, and the colon.

The peculiar appendages of the intestinal canal are, the salivary,
biliary, and anal vessels.

These parts are never all present together ; sometimes one is wanting,
and sometimes the other. For example : insects with a suctorial mouth
never possess apparent pharynx, but the oesophagus originates imme-
diately at the base of the sucking tube ; they also want the proven-
triculus, instead of which they possess a bladdered crop, which how-
ever does not occur in mandibulated insects. The part most frequently
deficient is the duodenum, which has hitherto been observed only in
some of the pentamerous Coleoptera , after which the coecum is least
frequently present, for it appears to be peculiar to those families only
the genera of which feed upon animal matter.

With respect to the appendages, the biliary vessels are seldom want-
ing ( Chermes , Aphis), the salivary ones frequently, but the anal vessels
very generally.

THE PHARYNX.

§ 101.

The pharynx is the distended commencement of the oesophagus,
bordering upon the cavity of the mouth, and is found, as we have
recently remarked, only in the mandibulata, consequently in the Cole-
optera, Orihoptera, Neuroptera, and Hymenoptera. In these it is
nothing else than the almost trumpet-shaped commencement of the
oesophagus, and in the majority of cases is not separated from it by any
evident difference of texture or construction. In some of the grass-
hoppers and cockroaches, in which, in consequence of their large man-
dibles, the cavity 'of their mouth is very expansive, their pharynx is very
much distended, and more clearly separated from the much narrower
oesophagus *. Its membrane is more dense and compact than that of
the latter, excepting which it displays no other difference. The mucous
and muscular membranes lie close together, and it is scarcely possible to>

* Ramdohr, ib. PI. I. f. 9.

124

ANATOMY.

distinguish the proper membrane between them as a separate layer. A
free space is naturally not found, as in the stomach.

THE OESOPHAGUS.

§ 102.

The oesophagus (PI. XVII. 22, a, a,) extends from the pharynx to
the stomach ; it is distinguished from the former by its smaller capacity,
and from the latter by a variation in structure. The most remarkable
form of the oesophagus is doubtlessly its very general furcate division
in the Lepidoptera, and that from each of the two spiral sucking
tubes it originates by a distinct branch, which branches then
unite into one channel. In general the branches of the fork are
very short, but in the swallow-tail butterfly ( Pieris Machaon, O.)
their union into one tube commences only at the thorax *. In the
other orders of insects the oesophagus passes through the entire cavity
of the thorax as a simple tube, and either terminates where the cavity
of the abdomen commences, or before this, within the thorax itself ; for
example, in its centre in those insects the cavity of whose thorax is
broad, and which consequently admits of a greater expansion of the
organs which traverse it. The length of the oesophagus therefore
depends upon the length and dimensions of the thorax. Insects with
a thin and narrow, and in particular with a petiolated abdomen, have
a long oesophagus, when the thorax also is long ( Pimpla, Fcenus ) ; and
it is the longer in proportion to the entire intestinal canal, the shorter,
narrower, and smaller we find the abdomen. The most remarkable
proportions must occur in this respect in the genus Evania, but which
has never yet been anatomically investigated. The longest oesophagus
yet observed consisted of more than half of the entire intestinal canalf ;
and among the shortest is that of the cockchafer, which occupies
scarcely one-sixtieth of the entire length of that canal J.

We are already acquainted with the texture of the oesophagus ; its
central layer however is very slight, whence the two other membranes
lie closer together, which, as Ramdohr assures us, makes their separation
very difficult. The inner membrane is generally here quite uniform, much
more rarely thicker in parts, almost like parchment, or, as in Carabus,

* See Treviranus, Vermischte Schriften, vol. ii. p. 200.

f In Pimpla Enervator and Pompilus viaticus , Ramdohr, PI. III. f. 2 and 3.

X Ramdohr, PI. III. f. 1.

THE ORGANS OF NUTRITION.

125

Meloe, Chrysomela, Blatta, and the grasshoppers (PI. XXI. f. 2 and
3), internally covered with short stiff setae and teeth ; the muscular
fibres of the’ exterior membrane generally lie regularly above each
other, but they sometimes form a loose confused net-work from open
spaces remaining here and therebetween them.

The separation of the oesophagus from the stomach is effected some-
times by a positive constriction ( Diptera , PI. XVIII. f. 3.) ; it occa-
sionally passes insensibly into it, and sometimes the crop intervenes
between them, as the organ of transition ; in this case the oesophagus
expands by degrees into a sack-shaped crop ( ingluvies , PI. XVIII.
f. 1. b, B,) which' takes the place of a first stomach, and prepares the
swallowed food for digestion. In Gryilotalpa it occurs as a perfectly
sack-shaped appendage of the oesophagus * (PL XXI. f. 7-)* To
facilitate this the inner surface of the crop is covered with glands (for
example, in Dyticus, Blatta, &c.), the secretion of which has the func-
tion of a preparing juice. Such an expansion of the oesophagus before
the proventriculus might readily be considered as analogous to the
crop of the higher animals, of the birds, for example; an opinion which
Ch. L. Nitzsch has already propounded f . The expansion, however,
without a contemporaneous proventriculus, is of a different and peculiar
kind, namely, the sucking stomach, indicated by G. R. Treviranus,
and which we proceed to describe.

THE SUCKING STOMACH.

§ 103.

The Hymenoptera, Lepidoptera , and Diptera are the orders in which
the proventriculus is deficient, but they possess, nevertheless, a bladder-
shaped distension of the oesophagus (PI. XVII. and XVIII. c, c,),
which in the first lies directly in front of the cardia ; in the second it
forms a distinct bag, which opens into the oesophagus, contiguous to
the cardia ; and in the third it hangs appended to the oesophagus by
means of a long thin duct, frequently far in front of the opening of the
stomach. This organ is the before-named sucking stomach. Its function
does not consist in being a receptacle for nutriment, but in promoting
the suction of food, by distending, at the will of the insect, and thus,
by the rarefaction of the air contained within it, facilitating the rise of

* See Suckow, infHeusing. Zeitschrift, f. d. Org. Pliys. vol. 3. p. 53, PI. II. f. 134.

"t Gattungen der Thier-Inseckten, Germar’s Magaz. iii. p. 280.

126

ANATOMY.

fluids in the proboscis and oesophagus. Insects which client are natu-
rally deficient in this apparatus, or at least in this function of it ; in
them it is a true crop.

In the Hymenoptera (PI. XVII. f. 10, c,) the sucking stomach is a
distension of the oesophagus in front of the cardia, and consequently
perfectly resembles a true crop. Indeed, in those families of this order,
which possess more a mandibulate apparatus than a suctorial, this suck-
ing stomach must gradually become superfluous ; and it is, consequently,
so little distinct from the oesophagus that it was formerly always
described with it, and as nodose * * * §. It exists however as a distinctly
defined organ in the families of the bees and wasps, which possess a
true suctorial apparatus ,* and here it is a large bag, which hangs below
the oesophagus, in front of the mouth of the stomach f. If it be empty
it lies folded longitudinally ; when filled with air it is distended as a
transparent bladder, and embraces the long funnel-shaped mouth of
the stomach, which is furnished at its aperture with valves.

In the Lepidoplera (PI. XVIII. f. 5.) we find the sucking stomach
still more distinctly separated from the oesophagus. In these it projects
with a short neck at right angles from the end of the oesophagus, and
when simple it lies as a folded bladder contiguous to and over the
stomach, or upon each side of it when, as in Zygcena J, it consists of
two equal halves. This division is sometimes unequal, when a smaller
bladder hangs beneath the large one §. It is always proportionate in
compass to the length of the proboscis, so that it completely vanishes
when the proboscis dwindles to a short cone, as in Gastrophaga pini
and Cossus ligniperda ||.

Many Neuropterci, for example, the genera Hemerobius and Phry -
ganea , have apparently similar bags, which are likewise inactively
folded, but which also admit, like those of the Lepidoptera, of being
distended into tight bladders. These organs may possibly be sucking
stomachs, particularly as these insects, although provided with a man-
dibulate apparatus, take food more by suction (this is the case espe-
cially in Phry ganea) than by mastication.

* For example, in the Tenthredos and Ichneumons , Ramdohr, PI. XIII. f. 2 and 3.
and PI. XIY. f. 2.

f Ramdohr, Pi. XII. f. 6. PI. XIII. f. 1. PI. XIY. f. 3. Treviranus, PL XIV. f. 3.
and PI. XVI. f. 3.

X Ramdohr, PI. XVIII. f. 1.

§ Treviranus, PI. IX. v, v.

|| lb. p. 109.

THE ORGANS OF NUTRITION.

127

In the Diplera, lastly, (PI. XVIII. f. 2 and 3, c, c5) the sucking
stomach is still more distinctly divided from the oesophagus, and is a
single mouthed bag, having one or several ends, and furnished with a
solitary evacuating duct. When empty it is small and wrinkled, but
when distended it is of large dimensions. In its natural situation it
lies contiguous to and over the stomach, aX the very commencement of
the abdomen, whence its delicate evacuating duct, rising anteriorly,
accompanies the stomach as far as the oesophagus, of the size of which
it generally is, and opens into it more or less closely to the cardia *.
According to Ramdohr this organ is the food bag ( speisesack ), as it
serves for the reception of food. Meckel calls it, from the same cause,
the honey vessel ( [honigbehälter ), and he found in it a peculiar, coloured
liquid. But Treviranus’ representation is much too illustrative, and
his investigations in insects opened alive much too conclusive to admit
of the least doubt being entertained of the function of this organ.

The Hemiptercij which likewise live upon imbibed juices, have no
sucking stomach, nor any analogous apparatus ; this is the case also
in the Pupipara and the flea, although they must necessarily be classed
among the Diptera f.

THE PROVENTRICULUS.

§ 104.

The PROVENTRICULUS (PI. XVII. f. 8 & p. 21, f. 8 — 10) is the
third division of the intestinal canal, if we may consider the crop or
sucking stomach as nothing but a distension of the oesophagus. It is a
small narrow and tubular cavity, much folded within, and furnished
with teeth, spines, or projecting horny ridges. It lies directly in front
of the mouth of the stomach, and as which it may properly be con-
sidered. It is found in all mandibulate insects which feed upon hard
substances, or require the comminution of their food previous to
digestion; consequently in all the carnivorous tribes ( Carabodea ,
Hydrocantharides , Br achy pier a), the wood-beetles ( Ceramhycina ,
but here somewhat altered), many Rhinchophora , the Orthoptera ,
(with the exception of the Phasmce and the Grylli, whose whole crop
is furnished with spines which serve to triturate the food), and the
Neuroptera. Exteriorly it has always a round somewhat ovate appear-

* See Ramdohr, PL XVIII.— XXI., and Trevir. PI. XVII.
t See Ramdohr, PI. XXI. f. 6., and PL XXIII. f. 2.

128

ANATOMY.

ance, and is compact, opaque, and more distinctly muscular than the
rest of the intestinal canal. It consequently answers to the gizzard of
the gallinaceous birds, an analogy which still more strongly confirms
the general analogy of organisation existing between insects and birds.

A closer anatomical investigation of this organ displays two very
distinctly-separated membranes, the exterior of which is tight and
muscular, and the interior folded, smooth, and partially horny. The
folds of the inner membrane are by no means accidental, but perfectly
regular and differently formed in the several families. In the preda-
ceous beetles ( Cicindelacea and Carabodea, PI. XVII. f. 8), four is the
prevalent number. Four large arched folds, densely covered with short
horny spines, bend inwardly in the cavity of the organ, and between
these lie four smaller ones, which are sharply ridged in front. Within
the large folds there are four robust bundles of muscles, which unite
above and below, and thus form a closing muscle at each opening. The
similarly constructed mouth of the stomach in Staphylinus has five
large folds and as many small ones. In Cryptorhynchus Lapathi there
are nine equal prismatic folds, from the inner ridges of which originate
two rows of diverging horny processes, which meeting from fold to
fold, separate a central star-shaped space from the entire cavity *. In
the capricorn beetles ( Cerambycina ) there is no cavity at all, but at
the inner margin of the cardia there are four large and four smaller
horny plates (PI. XXII. f. 1, Lamia cedilis ). The Orthoptera (for
example, Achela,) have six chief plates, which are covered with scale-
shaped horny plates. In the Termites (PI. XXI. f. 8 — 10.) I disco-
vered a proventriculus, which consisted of a ring of twelve equal broad
folds, between which again twelve finer and sharp edged ones lay.
Around this ring, which formed the central girdle of the cavity of the
organ, there were six strong fasciculi of muscles, which united above
and below like the ribs of a gothic arch, and thus formed closing
muscles. In Blatta, instead of folds we find hooked horny teeth,
which spring from a broad base at the sides of the stomach, and
project into its cavity. In Gryllus migralorius (PI. XXI. f. 1 — 6.)
I found no proventriculus, but the entire pharynx and crop were
armed with rows of small but differently sized teeth, which, running
longitudinally, formed in the centre transverse waved lines, but
towards the cardia again stand in twos and threes upon elevated mus-

* Ramdohr, PI. X. f. 1—4.

THE ORGANS OF NUTRITION.

129

cular ridges. The cardia itself was armed with six Y-shaped horny
teeth (PI. XXI. f. 6. a, a). In Muller’s representation of the intes-
tinal canal of Phasma no proventriculus is visible *, I consequently
surmise they would present a similar structure.

The exterior skin of this organ is tense, not folded, and it closely
incloses the interior one as a similarly shaped distended bag. It agrees
in structure with the muscular membrane of the intestinal canal.
The space between both is occupied by fasciculi of muscles, and the
spongy layer or middle membrane must necessarily be deficient here as
well as in the crop, it being the produce of digestion, and therefore can
only be present where this has commenced.

The larvae of all the above-named insects whose metamorphosis is
complete, entirely want this organ, and in them the pharynx passes
immediately into the considerably wider stomach. We do not either
observe in the very voracious caterpillars of the Lepidoptera any further
comminuting stomach.

§ 105.

THE STOMACH.

The stomach ( ventriculus , PI. XVII. — XXII. d, d), according to
most entomologists, is that portion of the intestinal canal which extends
from the end of the oesophagus, or of the crop, to the opening of the eva-
cuating ducts of the biliary vessels. Straus, Treviranus, and Joh.
Müller f call it the duodenum, as digestion commences in it, in those
orders which have the proventriculus, and perhaps this interpretation
may be more correct than that hitherto used.

Upon examining the form of this portion of the intestine it soon
becomes apparent that it is subject to many changes ; it always
approaches more or less to the tubular, but it at the same time distin-
guishes itself from the following divisions of the canal by its greater
compass. The shorter the stomach is the further does it recede from
the tubular form, and approaches to the ovate, conical, or bladder-
shaped.

The Lepidoptera (PI. XVIII. f. 5. d) have the smallest stomachs
of all insects. In these it takes the shape of an egg, the ends of which
contract into narrow tubes, and its upper surface is folded in irregular

* Nova acta Phys. Med. n. cur. T. 12. B. PI. L. f. 2.
t Joh. Müllerde Glandul. Secern. Struct. Pen. p. 68. Lip*. 1831, fol.
K

130

ANATOMY.

constrictions. Generally, upon both upper and under surface, a narrow
sinewy or muscular stripe runs longitudinally, for the purpose of
strengthening the there more delicate envelope. Meckel informs us *
that this stomach in Acherontia Atropos is shaggy externally, a solitary
instance of this structure in the Lepidoptera.

The longitudinal, more tubular, and regularly transversely folded
stomach of the Hymenoptera (PI. XVII. f. 10. d) approaches very closely
in structure to that of the Lepidoptera. It commences with a funnel-
shaped orifice, which is evidently analogous to the before-described
proventriculus, and as such projects into the cavity of the sucking
stomach, which can be closed by valves that open inwardly f . This
funnel-shaped orifice facilitates the passage of the food from the oeso-
phagus into the stomach, its aperture being thereby brought nearer to
the former, indeed, during suction, rising quite up to it ; the valves
however preventing the return of the chyme into the sucking stomach.
This structure of the stomach is found in all the Hymenoptera, but it
varies much in compass ; in some^irez) it is short, broad, and straight,
the crop, on the contrary, is very long and nodose; in others ( Chrysis )
it is distended in the middle and recurvate at the extremity ; in the
bees and wasps it is of tolerably equal breadth, but not straight, for it
bends inwardly at both ends, so that it is partially inclined towards the
axis of the body.

In the larvae of these insects the whole intestinal canal (PI. XVII.
f. 9. d) consists but of this transversely folded stomach, and all the fol-
lowing divisions, including also the anus, are deficient : this stomach,
consequently, is more compactly constructed in them than in any other
insect, it being composed of five skins, whereas the others have but
three. It is probable that both the mucous and muscular membranes
have separated into two layers J.

In the Diptera (PI. XVIII. f. 3. d) the stomach is a long tube, which
frequently distends at the two extremities, and is narrowest in the
centre ( Musca ); a callous ring is found at the cardia, which is the
remains of a small bladder existing there in the larva state ; the vicinity
of the cardia is granulated, that is, uneven, arising from transverse and
longitudinal striae. Some of the large group (perhaps all), which
Latreille calls the Diptera Athericera, have peculiar, glandular,

* Yerglei. Anatomie, vol. iv. p. 87.

•f* Compare Treviranus, Vermischte Schriften, vol. ii. PI. XV. f. 2.

+ Compare Suckow, in Heusinger Zeitschr. f. d. Org. Phys. vol. iii. p. 18. PI. VI. f. 131.

THE ORGANS OF NUTRITION.

131

secretory organs which evacuate themselves at the very commencement
of the stomach, closely behind the cardia *. They are doubtlessly the
same forms we shall more fully describe below in the Orthoptera, and
which have been considered as the analogues of the pyloric caecum of
the pancreas, or liver.

The Neuroptera have a short, sometimes smooth, sometimes trans-
versely striated cylindrical or conical stomach, in front of which, at
least in Myrmecoleon and Panorpa, there is a distinct proventriculus.
This is wanting in the Libellulce and Ephemer ce : their stomach is

long, cylindrical, and separated from the pharynx by a slight con-

striction only. Lepisma, which genus, as well as the two families of
Termites and the mandibulate parasites, I unite in the order JDicty-
otoptera , has a very small stomach, and in front of it a proventriculus
armed with six teeth, contiguous to which lies a broader and larger

crop. The same is the case in the Termites, but their stomach is

longer. The Mallophaga t have also a tolerably large crop, but the
true stomach is small, and is provided beyond the cardia with two con-
siderable points ; perhaps they, as well as the genus Psocus, for both
devour hard materials (the former, for example, feathers), are also
furnished with a proventriculus.

The three remaining orders display stomachs of a much more complex
form than the preceding.

In the Coleoptera we find a considerable variety in the structure of
the stomach, we observe the most simple in those Lamellicornia which
feed upon feculent substances, or upon the juices of flowers (for ex.,
Scarabceus, PI. XX. f. 2., Melolontha, Trichius'). In these the short
and narrow oesophagus passes, without any distinct indication of its
termination, gradually into a very long, cylindrical, and equally wide
stomach. The object of this great length of the stomach is evidently
to prepare the food more fully for assimilation, for in the larvae of
these insects it is much shorter, but in compensation it is supplied at
both ends with blind, pointed appendages (organs of secretion), of
which, in some cases (for example, Hister, a genus closely approximate
to the Lamellicornia ,) traces still remain in the perfect insect. Next
to these, the tribes which feed upon fresh vegetable matter, and parti-
cularly the juices of flowers, the Chrysomelina and Cerambycina, have

* Bombylius , Leptis , Chrysotoxum , see Ramdohr, PI. XX. and XXI.

f Ch. L. Nitzsch, in Germar’s Magaz. der Entomol., vol. iii. p. 280. and vol. iv.

p. 277.

132

ANATOMY.

the most simple stomachs ; in these also it is a long, tolerably broad,
smooth tube, which rarely (for ex., in Chrysomela ,) is beset with short
flocks. These flocks are portions of the internal mucous membrane
which pass through the muscular membrane, but are not covered by it.
In some genera (for ex., Lema, Callickroma moschatum,) portions of
this tubular stomach are broader, others again narrower, but in the
majority it gradually decreases in size.

The structure is more anomalous in other families, which, although
chiefly feeding upon vegetable matter, consume it in a more crude and
unprepared state, viz , as fresh leaves or harder fruits. The majority
of these have also a long, cylindrical stomach, but the oesophagus is
divided from it by a distinct muscular ring, and it is more tense, and
occasionally, as in the Hymenoplera, transversely ringed. Among
these are the Rhynchophora , many of which even possess the proven-
triculus and the before-mentioned flocks, (for ex., Cryptorhynchus La -
pathi), the Vesicifica (ps Lytta , Mylabris, Meloe ), the tortoise-beetles
(Cassidaria) , & c.

But the Buprestidea , of all the vegetable feeders, exhibit the most
remarkable structure of the stomach : in these, at its very commence-
ment, it distends on each side into a long blind appendage, equal
indeed in length to the stomach itself ; and this appendage, as well as
the commencement of the stomach, is furnished throughout three parts
of its extent with short, blind processes, like that of the flesh feeders.
The remainder of the cylindrical stomach is smooth *. The Elaterodea
form a transition to this remarkable arrangement, for in them the com-
mencement of the stomach has on the two opposite sides a short folded
pocket, it then continues, as a narrow, cylindrical, transversely folded
tube, and distends widely at its termination t.

The Carnivora display the most complex structure of this organ
among the Coleopter a (PI. XIX. f. 4. d, d). Here the before-described
proventriculus lies in front of the stomach, from which it is separated
by a distinct constriction ; the stomach itself is not very long, at least
considerably shorter than in the vegetable feeders, and it is covered
upon the whole or major part of the upper surface with long, thin,
and blind flocks. These flocks originate, as was already observed in
Chrysomela , from the inner mucous membrane of the stomach, and

* Compare H. M. Gäde, in the Nova Acta Phys. Med., vol. xi. part ii. p. 329. ; and
J. F. Meckel’s Beiträge zur Vergl. Anat., vol. i. part ii. p. 129.

f Ramdohr, PI. XL f. 1.

THE ORGANS OF NUTRITION.

133

pass through the exterior muscular membrane, the filaments of which
it pushes on one side. They doubtlessly consist of secerning organs,
whose secretion makes more soluble the heavily digestible animal
matter. These flocks are found in the Cicindelacea, the Carabodea,
the Hydrocantharides, the th'achyptera, the Peltodea, the Melanoso-
mata , and the Helopodea.

The stomach of the majority of the Orthoptera is still more artifi-
cially constructed, although in many respects not dissimilar to that just
described. They equally have a crop and proventriculus, the stomach
itself is not very long, but tolerably broad and most frequently
transversely ringed above; at its mouth there are broad, sack-shaped,
blind appendages, which are not mere processes of the mucous
membrane, but are also covered by the layer of muscular mem-
brane. There are two such appendages in Acheta and Gryllotalpa ,
and as many in Locusla, but here shorter, and more vesicular. In
Gryllus migratorius I found six tubular ones (PL XXI. f. 6.) length-
ened above and below, each of which opened into the stomach by an
oval aperture (the same a, a, a,) and thin tubes, which lay convo-
luted in the tubular appendages passed into these openings from the
internal membrane of the stomach (the same fig. 5.) ; consequently
these apertures do not merely open into the stomach itself, but also
between the innermost and central membranes of the stomach (see
fig. 2. at the * ). In Blatta there are eight such appendages, four
short and four long ; these are also, without doubt, organs of secretion,
which have been not inappropriately compared to the blind appendages
in the pylorus of fishes. They would thus be analogous to a gastral
salivary gland, or pancreas.

We have yet to examine the stomach of the Hemiptera, which is
the most composite of all (PI. XX. f. 3). The narrow, and generally
long oesophagus suddenly distends itself upon its entrance into the
abdomen into a broad, bladder-shaped, generally long, and often irre-
gularly folded stomach (d), which is, without doubt, analogous to the
crop of the other orders. The Hemiptera which imbibe raw juices,
either animal or vegetable, require several successive stomachs for the
gradual transformation of these substances. The first of these stomachs
serves as a preparatory receptacle, wherein the materials accumulate,
and where they are slightly changed, that they may be more effectively
elaborated in the following divisions. This first stomach is consequently
the widest of all, and thus corresponds to the crop of the Coleopter a

134

ANATOMY.

and Orthoptera. With respect to its precise form, it is smooth
and cylindrical in Nepa, somewhat wider and transversely ringed in
Lygceus, shorter but wider, with irregular longitudinal folds, which
form apparent large pockets, in Cimex. In Cimex rufipes two com-
pact, round, transversely ringed bodies lie above, contiguous to the
cardia, one upon each side of it. In Cicada the first stomach is short,
but also very broad and bladder-shaped. The second stomach {d *) is
in general the narrowest, but always the longest ; it has the appearance
of a compact muscular tube, whose function can be no other than the
further preparation of the imbibed juices ; it is consequently of a more
solid structure, and indeed in Nepa * it is internally covered with ele-
vated ridges, which form a reticulation of hexagonal cells. Its function
and even structure therefore correspond with the proventriculus; it more
triturates the food than extracts it. It is separated from the following
stomach by a perfect sphincter, and sometimes is distended in front of
this into a large bladder (d**, Cimex rufipes , C.baccarum) , which must
not be considered as a proper stomach but as a second receptacle for the
triturated matter, as a second crop before the third stomach. This
distension, in greater or less compass, appears peculiar to all the bugs,
but is wanting in the rest of the Hemiptera. In the Cicada the
second stomach is nodose, very wide in front, growing gradually nar-
rower behind. The third and last stomach (d***) is in the bugs
wider than the second, but narrower than the crop lying in front of it.
In form it resembles the transversely striped stomach of »the bees, its
cavity being formed by four half cylindrical tubes ( Cimex baccarum
and C. prasinus ), and these half tubes completely separate in C.
rufipes , so that their third stomach properly consists of four contiguous
stomachs In many water bugs. Hydrocorides (for ex., Nepa, Nau-
coris ), this stomach is wanting, but in compensation the second, as
well as the following portion of the intestine, are longer, as in the land
bugs ( Geocorides ). In the Cicadaria (PI. XVIII. f. 1. d**) it is of
the same length as the second, but of less breadth, while the second
(d*) is granulated upon its exterior surface. Separated from the
former by a distinct sphincter, it, like it, gradually decreases and turns
upwards into the first stomach, indicated as the crop (d), so that the
transmission of the food describes a complete circle in the three

* Ramdohr, PI. XXII. f. 8.

f Compare G. R. Treviranus, in the Annalen der Wetterausch. Gesellsch. sur die
Naturgesch, vol. i. No. ii.

THE ORGANS OP NUTRITION.

135

stomachs. The remainder of the intestine is continued at the opposite
side of the stomach, and it is there also that the biliary vessels empty
themselves.

Thus much upon the form of the stomach in the several orders of
insects j with respect to its structure, almost all that can be said upon
it has been mentioned above, in treating of the nutrimental canal. The
three membranes described there are found also in the stomach, and
here particularly distinct. They are here more loosely united than in
any other portion of the intestinal canal, and their exhibition is conse-
quently attended with no difficulty. The middle membrane is attached
more closely to the innermost, and the granules are found in it which
Straus (see above, § 96.) indicated as gastral glands ; between this and
the inner mucous membrane the chyle collects, and then transuding
through the latter, it enters the abdominal cavity, undulating about all
the organs.

But little also can be said of the situation of the stomach, as it is not
subject to much deviation ; it is always found in the abdomen, whilst
the oesophagus, and very generally the crop, are seated in the thorax.
As soon, therefore, as the intestinal canal enters the abdomen it becomes
the stomach, and frequently, indeed, even in the thorax ( Melolontha
and many others). If the intestinal canal be only as long as the
body, the stomach then lies directly in its axis, but if it be longer,
it then makes windings, which are the larger and more numerous
the longer and more extended it happens to be. These convolutions
generally lie in the anterior portion of the abdoipen, encompassed and
retained in their place by the ramifying branches of the air vessels, the
hinder portion being chiefly occupied by the sexual organs ; the stomach
and intestine also approaches closer to the back, the internal sexual
organs filling the ventral portion, or the space beneath the nutrimental
canal.

§ 106.

THE DUODENUM.

The divisions of the nutrimental canal which follow the stomach are
generally more simple than the preceding, and also subject to fewer
changes of form. In breadth they do not generally, with the exception
of the last, or colon, equal that of the stomach ; they are mostly nar-
rower, and also more delicately constructed. This entire intestine also
consists of the three membranes, which, however, often lie more closely

136

ANATOMY.

attached to each other, but frequently in the ilium, particularly when
the muscular membrane is very delicate ( Lamia cedilis ) *, they leave
a considerable space between them. Here and there also the muscular
membrane is thicker than in the stomach, which may possibly be
explained by the distribution of similar fasciculi of fibres over a nar-
rower space, whereas in those cases in which this intestine is as
distended as the stomach (for example. Lamia cedilis,') the muscular
membrane of both is uniform in its consistency.

The passage of the stomach into the duodenum is formed by a dis-
tinct constriction, which supplants a sphincter, or is possibly one ; the
ring thus projecting internally is called 'pylorus , immediately beyond
which the mouth of the gall vessels pierce the intestinal membranes.

This intestine is also separated into different divisions by means of
constrictions, which have different functions, and have consequently
received different names.

The first of these divisions is called the duodenum according to Ram-
dohr, but it is scarcely analogous to the similarly named portion of the
intestinal canal in the superior animals, but it more probably entirely
belongs to the following ilium. In the few beetles in which it has been
hitherto observed ( Silpha , Necrophorus, Melolontha, Lampyris) it
generally appears as a short, smooth tube, of equal width, or narrower
(. Melolontha ) than the ilium, from which it is distinguished exteriorly
by the ringed constrictions of the latter {Necrophorus f, Silpha J). A
stronger ringed constriction separates it from the following portion of
the small intestines, r

§ 107.

THE ILIUM.

Wherever the duodenum is wanting the ilium (PI. XVII. — XXII.
E, e,) follows immediately upon the stomach, from which it is separated
by the above described pylorus. This portion of the intestine is likewise
sometimes wanting, so that the stomach lies immediately contiguous to
the colon ( Libellula §, Reduvius ||). This appears to be the general
rule of structure in the bugs ; and when even occasionally a small
portion of the intestine is found beyond the stomach in which the
biliary vessels bury themselves, it is nevertheless so inconsiderable

f lb., PI. V. f. 1. : lb., PI. IV. f. 2.

II lb., PI. XXV. f. 5.

Ramdohr, PI. IX. f. 6.

§ lb., PI. XV. f. 4.

THE ORGANS OP NUTRITION.

137

that it may consistently be considered as deficient. This deficiency in
them may be accounted for by the number of their stomachs, for that
transmutation of the food which is properly the function of the ilium
takes place in their third stomach, and which consequently renders the
ilium unnecessary.

With respect to its structure, we have already indicated some of its
peculiarities in treating upon the membranes of the stomach. Those of
the ilium are generally tenser than the latter ; it is invariably equally
distended, and, as it were, inflated, whereas the stomach is not un-
usually folded up. We have already mentioned that the ilium, as well
as the stomach, is frequently transversely ridged, and by this means is
distinguished from the duodenum.

The length and situation of the ilium varies considerably ; it is rarely
so long or longer than the body ( Necropkorus ), in general shorter, and
even shorter than the stomach. The latter proportions are found espe-
cially in the Chrysomelina , and in many others which feed upon
vegetable matter it is the general rule. In many of the carnivora, for
example, the water-beetles ( Hydrocantharides ), the ilium on the con-
trary, is longer than the stomach, particularly in their larvae, in which
it is twice as long; but this is not the case in the ground-beetles
( Cicindelacea and Carabodea), the ilium in them being not so long as
the stomach. The butterflies have the longest ilium, in proportion to the
stomach of all insects, for in them it is not merely twice as long, but
even three or four times the length of the stomach, which is the more
extraordinary as in the caterpillar it is excessively short, scarcely
extending to one-eighth of the length of that organ. In the Diplera
also it is shorter than the stomach ; in the bugs alone is it sometimes
wholly deficient. It is regularly wanting in the Libellulce and
Ephemera. There are no fixed laws which regulate the length of the
ilium, but Ramdohr has endeavoured to show its most prevalent pro-
portions to the stomach and the other parts ; they are as follows : — the
most usual relation to the stomach is as 1:1, or 1:3; to the whole
intestine 1 : 5, or likewise 1 : 3. Some of the proportions are extra-
ordinary, as in Necropkorus , viz., the ilium to the intestinal canal as
2 : 3, to the stomach as 9 : 4 ; indeed, this beetle has the longest ilium
of any yet investigated. In Tenthredo nigra it is very short, viz., in
proportion to the entire nutrimental canal it is as 1:17- In the cater-
pillars of the butterflies it is always very short, and in general it is

138

ANATOMY.

short in all larvae, and it is the shorter in proportion to the extension
of the stomach.

The situation of the ilium is so far determined that it is always found
beneath and contiguous to, and never above the stomach, but its situa-
tion in itself varies considerably. In perfect insects it is seldom straight,
but always so in those whose intestine is not longer than the body
(Gryllus, Phasma, the larvae of butterflies). In the opposite cases it
makes convolutions of different size and form, which are the more
numerous and larger the more extended the ilium itself is.

§ 108.

In some instances the ilium appears under a different form, namely,
gradually distended, and thus becoming clavate, which is however
peculiar to a few beetles only. According to Ramdolir, who considers a
thus distended ilium as a distinct portion of the intestine, it is called
the clavate intestine. In the Chrysomelina the short ilium is thus
frequently distended. In many of the capricorn beetles a somewhat
distended portion of the intestine is separated by a constriction from
the very narrow ilium, and this represents the clavate intestine.

In the Lamellicorjiia ( Melolontha , for ex.) the clavate intestine
appears likewise as a distended sack-shaped ilium, and is therefore
called by Ramdohr the thick intestine. It is particularly distinct
and large in the larvae of these beetles (PI. XX. f. 1. f) ; here, namely,
it appears as a broad bag here and there constricted, which, in its
natural situation, turns back upon the stomach from its commence-
ment, and extends as far as the length of the narrow ilium will admit,
consequently to the end of the stomach. The bag here contracts,
and the again narrow colon originates beneath it, in a bow of it,
taking its course in a contrary direction towards the anus. In the
perfect beetle (the same. fig. 2.) this bag is to be distinguished exte-
riorly only as a bellied distension of the ilium, which, at least in Melo-
lontha, has five slight impressions. But if this portion be opened five
elevated ridges are observed, which are divided by incisions at regular
distances, so that each band appears to consist of short, contiguous,
three-sided prisms*.

If the name of this portion of the intestine is to be determined accord-
ing to its divisional distance from the stomach it must be considered as

* Suckow in Heusinger, vol. iii. PI.

. f. 94. Straus Durckkeim, PL V. f. 8.

THE ORGANS OF NUTRITION.

139

the true ilium, which is however contradicted by its function, which,
like that of the caecum of the glires of the mammalia, subjects the
food to a second digestion and extraction before it is rejected. We are
convinced of this by the comparison of its state in the stomach, and
in this portion of the canal, for we find it here much more pappy than
there, but yet not so viscous as in the colon.

§ 109.

THE COLON.

The last division of the intestinal canal is called the colon (PI.
XVII. — XXII. h, h,). It is divided from the preceding portion of
the intestine by a valve which can completely shut its aperture. G. R.
Treviranus was the first to describe and figure it *. Its internal
surface, particularly near the mouth of the ilium, is thickly beset with
glandular warts or flocks, which are not found in the ilium itself. We
have observed glands only in the crop, and as their function there was
evidently the secretion of the first menstruum of the food, they may
here possibly produce a secretion to assist the rejection of the faeces.

The colon generally exceeds the ilium in size, but when the conical
or thick gut precedes it it is narrower ; but it then is even longer than
the ilium, which is not usually the case. The form of the colon
varies, sometimes cylindrical, or clavate, or distended above (bees) ;
sometimes sack- shaped ( Carabodea ), or longitudinally folded within
(caterpillars and the larvae of Calosoma). These folds are produced
by the internal intestinal membrane, and are either straight or waved,
and supported by horny ridges. The muscular membrane does not
assist to form these folds, but it is more compact and firmer than in
the preceding portions of the intestine, yet the above described thick
gut or occasional analogue (by situation) of the ilium is frequently
much more fibrous. The colon is also occasionally fenestrate, that is
to say, there are six ovate transparent spots in it which are surrounded
by a horny margin or edge, and form either one or two rows, varying
in situation, so that the spot in the lower row lies where in the upper
one is found the intervening space. This structure Suckow first
observed in the bees f . I found in Harpalus ruficornis a perfectly
similar structure of the colon, these fenestral spots were in the internal

* Vermischte Schriften, vol. ii. p. 105. PI. XII. f. 3.

-f* In Heusinger Zeitschr. f. d. Org. Ph., vol. iii. PI. VI.

140

ANATOMY.

membrane, and were very bright and transparent. According to
Ramdohr’s observations, the width of the colon is in proportion to
that of the pharynx (crop), for where the latter is broad so is also the
colon, and vice versa.

The situation of the colon is always determinate, for it is always
found at the apex of the abdomen, surrounded by its last segments.
The evacuating opening, or anus, is found in the last segment itself ;
it is covered above by a peculiar valve, and beneath this the anal
vessels, which we shall describe lower down, open themselves. The
corresponding lower valve conceals the sexual aperture, so that both
the anal and sexual apertures open into one cavity, which might be
called the cloaca, and which are separated only by a fold if no other
organ, for example, an ovipositor, be present. The anus, as well as the
ilium and its correspondent the thick gut, are wanting in the larvae of
the bees, wasps (PL XVII. f. 9.), the Formicaleo , and of perhaps all
the internal parasites, for example, the Ichneumons ; their intestinal
canal consisting of the pharynx and stomach, and a small bag beyond it,
into which the biliary vessels open themselves ; it is here that the faeces
collect, which are evacuated upon the perfect insect quitting the pupa
state, when it is provided with an anus.

§ 110.

THE CiECUM.

In many insects we find, in connection with the colon, a blind, sack-
shaped appendage, or rather similarly shaped superior distension of it
which we call caecum (PI. XIX. f. 3 and 4g, g). It originates at the
very commencement of the colon, contiguous to its connection with the
ilium, and extends anteriorly towards the stomach, in either larger or
smaller distension ; it is consequently not separated from the colon by
any constriction or valve, but both cavities are in immediate connection
with each other. This, as well as their uniformity of structure, proves
that it must only be considered as a distension of the colon. In form
this caecum is sometimes nodose ( Silpha ) and directed forwards, some-
times laterally distended ( Necrophorus ), sometimes it is a long tubular
point ( Dyticus ), sometimes a shorter cylindrical process of equal width
with the colon ( Nepa ), similar to this, but sometimes slightly con-
stricted at its commencement, we find it in the butterflies. It thence
appears that this portion of the intestine is more peculiar to the car-
nivorous tribes, as Ramdohr, somewhat justly, remarks ; yet its struc-

THE ORGANS OF NUTRITION.

141

ture in the nectar-sucking butterflies modifies this assertion. The
caecum might also here, as in the Mammalia , have the function of a
second .stomach, and thus, therefore, be more serviceable to the car-
nivora, which consume coarser materials than the vegetable feeders,
which are besides provided sometimes ( Melolontha , &c.) with ana-
logous organs, as the clavate and thick intestine. The caecum is repre-
sented in the Carabodea by the broad sack-shaped colon. The long
caecum of the water-beetles has, according to Leon Dufour, the func-
tion of a swimming bladder, which is much to be doubted in the Cole-
optera, they being provided with so many air vessels : we cannot either
well imagine how air can be introduced into it, certainly not through
the anus ; for it is not for this purpose that water-beetles raise their
anal ends to the surface of the water, but to take air beneath their
elytra, as has been long well known.

§ 111.

THE BILIARY VESSELS.

The biliary vessels ( vasa bilifera, (PI. XVII. — XXII. k, k,)
occupy the first place among those organs which, although distinct, stand
however in direct connection with the intestinal canal. They are narrow
filiform tubes, which open at one end into the duodenum, and where
this is wanting into the ilium close behind the pylorus, and at the
other end are either free and closed, or pass into each other and thus
apparently form one vessel, which pierces the intestinal membranes
with both its ends. The biliary vessels also, at least according to Ram-
dohr, sometimes empty themselves into the end of the stomach, some-
times (for example, in Meloe,) upon the limits of both, that it is
difficult to say whether it is the stomach or intestine. According to
Ramdohr, the mouth of the biliary vessels does not pierce the internal
intestinal membrane, but only the exterior muscular one, which
assertion, however, is contradicted by Meckel’s observation, for, by
pressing these vessels, he forced their contents into the intestine. In
fact, the biliary vessels always enter the cavity of the intestine, and
their mouths lie at the same height, forming a circle around it;
more rarely upon one side only, for example, in a vesicular disten-
sion of the ilium in Lygceus apterus. Other differences in the mode
of their evacuating themselves are not rare. In the flies ( Muscaria )
the four biliary vessels unite into two short stems, which open into the
intestine at its opposite sides, or all four form but one, as in Cimex

142

ANATOMY.

baccarum. Occasionally, also, the openings of the gall vessels do not
lie by the side of but above each other, for example, in some of the
Neuroptera, in which four of the eight biliary vessels enter upon the
one side and the other four upon the other side of the intestine ( Myr -
mccoleori). If many biliary vessels exist their mouths lie contiguously,
above and below each other, or although more rarely, all upon one side
( Acheta ), or else they unite into a tolerably long evacuating duct,
(for example, Gryllotalpa) .

In form these vessels are generally narrow, cylindrical, filiform, and
twisted, but they are not always of the same dimensions throughout :
many commence narrowly and afterwards double in size ; some, by means
of a spiral furrow, resemble a turned slip ; others have alternately
small vesicular distensions ( Musca ) ; a few have long rectangular pro-
cesses, which are occasionally furcate ( Melolontha vulgaris').

There are generally pour in number, never fewer, unless entirely
wanting ( Chermes , Aphis), sometimes there are six or eight, and they
are even, occasionally, innumerable. These differences in number are
regulated by the order to which the insect belongs as well as by its food,
whether it be vegetable or animal, as is shown in the following table : —

I. No biliary vessels, Chermes, Aphis.

II. Few (4 — 8) biliary vessels.

1 . Four biliary vessels.

a. Free at the end ; most Diptera, as well as the families

Termitina, Psocina, and Mallophaga, of the order

Dictyotoptera.

b. Anastomosing; many Coleoptera, Hemiptera, and

Diptera.

2. Six biliary vessels.

a. Anastomosing ; many Coleoptera, for example, Ce -

rambycina and Chrysomelina.

b. Free at the end, Lepidoptera.

3. Eight free biliary vessels, Neuroptera.

III. Many biliary vessels, Hymenoptera, Orthoptera, and the Dic-
tyotoptera subulicornia.

Occasionally the biliary vessels join the intestinal canal at a second
place, but this union takes place only with the exterior muscular mem-
brane, for it is attached by means of solitary fibres, but a second open-
ing into the intestine does not occur. This union is found chiefly in
those insects furnished with a clavate intestine (the analogue of the

THE ORGANS OF NUTRITION.

143

ilium), for example, the Cerambycina, most of the Neuroptera , and the
Cicadaria,

The length of the biliary vessels is in direct proportion to their num-
ber, for when there are but few they are very long, indeed the longest
of all (for example, Melolontlia) ; but they are short, on the contrary,
where they are numerous, for example, in Gryllotalpn, Libellula , &c.
The long biliary vessels lie generally around the intestine ; they first
ascend parallel to the stomach as far as the pharynx, they then return
and form a thick knot of vessels around the ilium ; where there are many,
some return upwards along the stomach, and the rest below along the
ilium. The length also of the single biliary vessels sometimes varies,
for example, in the Cerambycina, in which they form concentric circles,
but the two opposite sides are always of the same length.

The biliary vessels are also always more simply constructed than the
intestinal canal, for they appear to consist of but a single skin, which,
besides, is very delicate and transparent, so that their contents can be
distinctly recognised as a finely granulated mass. The delicacy of the
smooth shining case is proved by the difficulty of removing the biliary
vessels from the enveloping fatty substance, and by their being very
easily torn, even when the greatest precaution is used.

In colour they generally resemble the yellowish white of the intes-
tinal canal ; in some beetles (for example, Carahus , Dyticus ,) they are
of a dark brown, but which becomes paler as it approaches the opening.
In many caterpillars, while parallel with the stomach they are whitish,
but at the intestine of a saffrpn yellow ; Swammerdam thence applied
the name of saffron vessels to them.

It may be here remarked, at the close of our observations upon
the biliary vessels, that some insects in which they are numerous,
for example, the bees and wasps, have in their larvae state but few
(4 — 6) long and thick ones, which, by degrees, whilst during the pupa
state the remaining gall vessels are forming, shrink up, and become
shorter until they contract to the same length as the rest *. Do they
not perhaps entirely disappear, and are replaced by the shorter ones ?
Perhaps they are very different vessels possessing a different function,
which probably disappears when the intestine and anus become formed
in the insect.

* See Ramdohr, PI. XII.

144

ANATOMY.

§ 112.

THE SALIVARY VESSELS.

Cuvier says, in his “ Comparative Anatomy," that the secretory
organs of insects always assume a tubular form, and that consequently
conglomerate glands are wholly wanting in them. This assertion is
strictly true with respect to the biliary vessels, which have been con-
sidered as analogous to the liver, but in the salivary vessels we find
exceptions, and which are most strongly exemplified in the testes, some
of which (the epidydimis in Hyrdophilus ) possessing many accumulated
acini. Nevertheless, the form considered by Cuvier as universal is cer-
tainly the most general.

Under the name of salivary vessels we comprehend those glandular
appendages of the nutrimental canal which evacuate themselves either
into the mouth or into the commencement of the intestine in front of
the stomach, and by their secretion promote the digestion of the food.
The following are their chief differences : —

A. Salivary vessels which open into the mouth, generally beneath
the tongue, and more seldom at the base of the mandibles. They
take the following forms : —

1. As simple, long, undivided, twisted tubes ; thus in the ma-

jority of insects, viz., all butterflies, many beetles and flies.

2. As a narrow vessel which empties itself into one or two blad-

ders, whence the salivary duct originates ( Nepa , PL XXII.

f. 1 ; Cimex, PI. XX. f. 3. A, a; Sarcophaga ).

3. As a ramose vessel with blind branches, ( Blaps , PI. XXII.

f. 3).

4. As two long, cylindrical pipes, which unite into one evacu-

ating duct ( Reduvius , PL XXI. f. 15).

5. As four small, round bladders, each pair of which have a

common duct (Pulex, PI. XXI. f. 16 ; Lygceus , Cimex).

6. As a multitude of such vesicles in Nepa (PL XXII. f. 2).

7. As capitate tubes, in the free ends of which many very fine

vessels empty themselves ( Tabanus , PL XXII. f. 4).

8. As tubes which at intervals are surrounded by twirling blind

bags ( Cicada , PL XXII. f. 5).

9. As granulated glands which on each side unite into a salivary

duct, both of which join into a single evacuating duct ( Gryl -

THE ORGANS OF DIGESTION.

145

lus, PL XXI. f. 12.). J. Müller observed such granulated

salivary glands in Phasma ; Treviranus in Apis; and I

have found them in Locusla , Gryllus , and Termes.

B. The salivary vessels which do not empty themselves into the
mouth, but into the commencement of the stomach. These we
have already partially described, in treating of the stomach
( § 105), as short or long bags, which were either simple or fur-
nished with processes ( Buprestis ) ; other forms, as well as those
just cited, are found chiefly among the Diptera.

1. As two capitate tubes, in the free ends of which many delicate

vessels open, we perceive them in Hemerobius perla (PI.
XXII. f. 4).

2. As two short processes of the same width as the stomach, in

Leptis (PL XXII. f. 6. a , a,) and Acheta.

3. As two bags covered entirely with short blind processes in

Bombylius (PI. XXII. f. 7-) and Buprestis (§ 105).

4. As triangular processes, each edge of which is occupied by a

row of vesicles in Chrysotoxum (PI. XXII. f. 8).

5. As six narrow tubes, which surround the commencement of

the stomach in Gryllus (PI. XXI. f. 1 and 6).

6. We also consider the blind processes which clothe the stomach

in the predaceous beetles among the salivary vessels.

Salivary vessels which open into the mouth are found in all the
haustellate and in many mandibulate insects which feed upon hard sub-
stances. Ramdohr was the first to observe them amongst the beetles
in Cryptorhynchus Lapathi. In this insect he found a long twisted
vessel, which opened into the mouth, which is indeed contrary to all
analogy, for the salivary vessels are elsewhere found in pairs. Leon
Dufour subsequently discovered salivary vessels in many Heteromera ,
viz., (E dem er a, Mycterus, Mor della, &c. I have found them of the
above form among the Orthoptera, in Locusla , and Gryllus , and among
the Dictyotoptera in Termes . Among the Neuroptera, Hemerobius
and Phryganea exhibit salivary organs.

The salivary organs which empty themselves into the stomach are
found among the beetles, especially in those which devour flesh and
wood ; and in those Orthoptera also which feed upon hard vegetable
matter, and in the Diptera, among the Syrphodea, which consume
the nectar of flowers, and probably also their pollen. Among the
grasshoppers we occasionally find both kinds of salivary organs.

146

ANATOMY.

Where we meet with salivary vessels we generally find two ; some
insects have, on the contrary, four, each pair of wdiich unite into one
evacuating duct (Apis, Cimex , Pulex) ; Nepa has even six salivary
vessels, three on each side, all of which open into the cavity of the
mouth ; two unite on each side into one stem, the third, which has
been considered as a poison-secreting organ, remains separated as far
as the mouth.

Many larvae, particularly the caterpillars of the Lepidoptera, have
also four salivary vessels of different structure ; two are slender, very
long ( Cossus ), and filiform; two broader, sometimes bag-shaped (for
example, Cossus ligniperda, O.), and considerably shorter. The first
secrete a viscous liquid, from which the caterpillar spins its silk. The
evacuating ducts of both unite into one, and open into the under lip,
namely, into the canal of the above (§ 54) described spinneret. This
pipe would therefore be more correctly called spinning vessel. Such
spinning vessels are naturally found only in those larvae which prepare
a web for their pupa change, such as the caterpillars of the nocturnal
j Lepidoptera, the larvae of the saw-flies, and of the Phryganodea. It
distinguishes itself chiefly by its length and size from the true salivary
vessels, which are often very small and insignificant. The true salivary
vessels, according to Suckow *, open at the base of the upper mandible
with a small warty protuberance (PI. XXL f. 13), and remain even in
the perfected moth ; whereas the spinning vessels totally disappear
during the pupa state f .

In Myrmecoleon the spinning vessels lie at the anal end of the
abdomen, and true salivary vessels have not yet been observed in it J.

The structure of this organ appears, according to all investigations
hitherto instituted, to be very variable, for sometimes there are two
membranes (the muscular and mucous) and sometimes but one. The
former vary in consistency, but occasionally are uniform with those of
the intestine ; in the latter case they are transparent and delicate, and
occasionally granulated or irregular.

The length also of the salivary vessels differs much : in some cater-
pillars they are two or three times as long as the intestine ; in perfect
insects, on the contrary, they are generally shorter, and do not usually

* Suckow’s Physiol. Unternich. über Insecten und Krustenthiere, p. 28. PI. VII. f. 32. a.
f Ib.p. 29. PL II. f. 1— lO.h. h.

X Ramdohr, PL XVII. f. 1—4.

THE ORGANS OF DIGESTION.

147

extend beyond the thorax. It is thence that we detect the salivary
vessels, with the exception of the very long ones of caterpillars, only in
the thorax. They here lie around the pharynx, crop, or stomach, gene-
rally low down in the breast between the coxae of the legs, whilst their
meandering evacuating duct, rising from beneath the nutrimental canal,
ascends to the cavity of the mouth, and here, after having united with
its companion, opens beneath the tongue. Locusta displays this
aperture very distinctly. In the bees, in which the salivary organ
consists of four granulated valves, the anterior one lies in the head,
directly beneath the forehead, before the eyes, and was originally de-
scribed by Ramdohr as the organ of smell, but subsequently recognised
as the salivary gland. The evacuating duct empties itself into the tube
of the proboscideal tongue, and is a spiral vessel resembling the trachea,
as Treviranus has described and figured it * ; in Locusta I found it
simple, thin, and transparent, but accompanied by a delicate trachea,
which followed it throughout all its ramifications and divisions.

§ 113.

THE URINARY VESSELS.

As the last distinct organ, but which is doubtlessly in strict con-
nection with the digestive apparatus, we must take some notice of the
variously formed urinary vessels, which empty themselves above the
anus. These, like the salivary vessels, are sometimes mere vascular
canals, at others glandular bodies which in the latter case unite into
one duct, to which not rarely there is attached a vesicular distension —
the urinary bladder. The duct of the latter is always separated,
and never unites to those of the opposite side, and empties itself
laterally contiguous to and above the anus, but strictly separated from
it by the anal valve.

These vessels are found in all the Carabodea and the Hydrocantha-
rides, in many Heieromera ( Blaps ), and again in Bombylius and
Leptis, among the Diptera. Ramdohr, who first observed them, drew
them to the intestine, and called them anal vessels; but Leon Dufour
subsequently described many of their forms in detail +.

In their most simple form (in Harpalus ) the urinary vessels appear
as reniform bodies contiguous to the colon, whence a short evacuating

* Vermischte Schrif., vol. ii. p. 123. PL XV. f. 1.
f Annales des Sciences Natur., t. 8. p. 6. PI. XIX. and XX.

L 2

148

ANATOMY.

duct extends to the orifice. In Carabus auralus this body is a bunch
of small round vesicles ; in Car . cancellatus it is divided into two equal
halves, the two short ducts of which speedily unite into one. The
urinary bladder, which is wanting in Harpalus, is present in Carabus,
has the shape of a fig, and stands almost at right angles with the eva-
cuating duct. It is much the same in Cymindis burner alls ; in Aptinus
three equal ducts open into the bladder, each of which originates from
five granulated glands with five branches. In Brachinus the glands
are convolutions of shorter or longer, and sometimes furcate filaments.
In Chlcenius and Sphodrus there are many solitary granules, each of
which has a small duct, they all unite into one stem, which then opens
into the bladder.

In the water beetles (PI. XXI. f. 11.) the portion lying above, and
over the urinary bladder, is but a simple, twisted, but tolerably long,
although delicate vessel ; the bladder, on the contrary, is round, but
not petiolated. It is the same in Bombylius.

With respect to the structure of these organs, two membranes are
distinctly discerned in the evacuating duct, the interior of which is
much less than the exterior ; this is constricted by parallel transverse
rings. The glands also have occasionally ( Chlcenius velutinus ) similar
transverse rings, particularly when they are somewhat larger.

§ 114.

CHANGES IN THE INTESTINAL CANAL OCCASIONED BY THE
METAMORPHOSES.

In the preceding description of the nutrimental canal in insects,
we have restricted ourselves chiefly to their form and structure in the
perfect creature. As, nevertheless, the differences which are produced
in the nutrimental canal by their metamorphoses are by no means unim-
portant, for the intestinal canal in larvse assumes very generally a very
different form, and its changes are subject to peculiar laws, partially
influenced by the order to which it belongs, we must not omit taking
notice of them as far as is possible in a general sketch, and must there-
fore make room here for a description of these transformations.

Insects with an imperfect metamorphosis, viz. the Hemiptera ,
Orthoptera, and Dictyotopiera, have in all their stages a very uniform
nutrimental canal. We find in them the same divisions in the same
proportions, and even the appendages, such as the salivary and biliary
vessels, agree with those of the perfect insect. The whole change.

THE ORGANS OF DIGESTION.

149

therefore, which the nutrimental canal undergoes in these orders
consists in its lengthening in proportion to the increasing size of the
insect, and at the time of moulting it covers itself internally with a
new mucous membrane, the old one being rejected by the anus, or
probably absorbed. This changing of the skin in the intestine is
certainly remarkable, and proves, as well as the similar phenomenon in
cutaneous affections in man, in which the epidermis peels off (for ex-
ample, after scarlet fever), the perfect uniformity of the intestinal mucous
membrane with the exterior epidermis. The larvae of the Libellulce
alone appear to make a slight exception to the rule of the intestinal
canal remaining the same, their’s being somewhat larger, particularly
broader, than in the perfect insect, and in the latter the respiration of
the colon disappearing, which was peculiar to the former.

Insects with a perfect metamorphosis, on the contrary, undergo in
the intestinal canal, as well as exteriorly, important changes, which,
however, refer only to the form, the structure remaining constantly the
same. It is true the membranes are originally much more delicate,
looser, and admit of being more readily separated, particularly in the
stomach, but this difference gradually vanishes. During their larva
state the intestine assumes a new skin at every moulting f ; towards
the end of this period, and still more during their pupa state, the
intestine shrinks, particularly the stomach, and acquires thereby a
more compact appearance. It is the divisions of the nutrimental canal
and their relative lengths which chiefly vary, but these are regulated by
very different laws in the several orders, and consequently demand of
us an especial notice.

The maggots of the Dipier a (PI. XVIII. f. 2. maggot ; f. 3. fly) have
a longer intestine than the flies, but it is the stomach chiefly which
occasions this greater length. The sucking stomach is present, but
larger, more shortly pediculated, and, besides, there are large cylindrical
salivary bags, which in the course of their change transform themselves
into filiform salivary vessels. The biliary vessels remain uniform both
in number and shape. During the larva state the intestinal canal
remains unchanged, but it alters the more quickly in the pupa state ;

* Compare Suckow in Heusing. Zeitschr. f. d. Org. Phy. vol. ii. p. 24, &c.

f In the larvae without an anus ( Myrmecolcon , Vespas, Apis ) the old skin remains
in the bag behind the stomach (compare §. 105.), and is evacuated only after the pupa
state through the new-formed anus.

150

ANATOMY.

but it is still the stomach only which shortens, until it decreases to
scarcely one half of its former extent.

In the Lepidoptera, on the contrary (PI. XVIII. f. 4. caterpillar ;
5. imago), the intestinal canal lengthens, but so that here also the
stomach becomes shorter but the ilium longer. In the caterpillar the
broad, cylindrical, folded, and transversely ringed stomach occupies
more than two-thirds of the entire intestinal canal, and this is succeeded
by a shorter, scarcely narrower ilium ; the preceding pharynx is short,
and so short that it is observed only in the head. Contiguous to the
stomach lie the long twisted spinnerets, and attached to it are the six
united biliary vessels. In the imago the pharynx is long, and beneath
it lies the sucking stomach, of which we observe no trace in the cater-
pillar ; the stomach, on the contrary, is small, short, ovate, folded, and
narrow ; the ilium, again, long, filiform, twisted ; the colon broader,
elongated above into a short caecum, which is likewise deficient in the
caterpillar. The spinnerets disappear, but the salivary vessels, which
are very small in the caterpillar, become more distinct, larger, and
longer.

We have already noticed the very interesting metamorphosis of the
intestinal canal in the wasp and the bee. In the order of the Hymeno -
ptera also the law prevails of the stomach becoming smaller and nar-
rower whilst the pharynx and ilium become longer. This will also
apply to Myrmecoleon, in whose larva the colon becomes the spinneret.

But of all the orders the Coleoptera display the greatest changes of
the intestinal canal. The larvae of the carnivora wholly want the folded
horny orifice of the stomach (PI. XIX. f. 1 and 3)/# Their stomach is
broad, but smooth, and not beset with filamentary processes ; the ilium
is also broad, but short, and much shorter than after the metamorphosis.
This consists in the crop distending, the proventriculus forming itself,
and the stomach sending forth filamentary processes. In the Cara-
bodea the ilium becomes much longer ; but in the water beetles, where
it is already very long, it appears to become somewhat shorter, at least
in Dyticus marginalis, according to Dutrochet, whose investigations
I have repeated, and can now confirm (see PI. XIX. f. 3. the larva ;
f. 4. the beetle). In the vegetable feeders, namely, in the Lamelli-
cornia, the intestinal canal in the larvae is triflingly longer than the
body, whereas in the perfect insect it is three or four times as long.
The larvae have a long, broad, cylindrical stomach beset with filaments

THE ORGANS OF DIGESTION.

151

at its commencement and end ; a short, narrow ilium ; a broad, sack-
shaped thick-intestine ; and a tolerably long but not broad colon : the
beetles have a very long but narrower cylindrical stomach, an ilium
resembling that of the larvae, a much narrower, gradually distending,
thick-intestine, and a longer cylindrical colon, which distends very
widely close to the anus. In both cases, consequently, the intestinal
canal is longer in the perfect state than in the larva, but in the vege-
table feeders more considerably so than in the carnivora, in which it,
namely in Dyticus, is shorter. Whereas the beetle has a much more
complex intestine, and more organs to effect the change and trans-
formation of the food than the larva, which is the more remarkable,
as both, at least generally, take the same food, which is not always the
case in the other orders, for example, in the Lepidoptera and flies.

§ 115.

II. THE FATTY MASS, OR RETE.

The fatty mass of insects is a web of generally white or yellow
ragged or stringy substance interwoven in every possible way, enve-
loping the intestinal canal and the organs connected with it, as well as
all the other internal parts, but it is never in direct immediate connec-
tion with any organ. It receives its name from its undeniable resem-
blance to the fat of the higher animals, and which is expressed in the
above peculiarity, and even more strongly in other circumstances. It
thence appears that it forms no portion of the intestinal canal, being no-
where in connection with it, but as it is the produce of digestion and
as it is increased or decreased by the perfection or imperfection of the
function of digestion, it must therefore, as standing in relation to the
organs of nutriment, be treated of and described when treating of them.
We are the more strongly impelled to this by the opinion expressed by
Oken, and which Treviranus has recently supported by analogies, that
the fatty mass of insects must be considered as their liver. Indeed in
the scorpion a substance similar to the fatty mass stands in connection
with the nu trimental canal by means of vessels, but they possess
besides two twisted biliary vessels, which likewise here and there quit
that substance. In all true insects, however, we find no such close
connection of both organs, and if it cannot be denied that the fatty
mass is of importance to digestion, and that much nutrimental matter
is derived from it, yet this admission proves by no means its analogy
to the liver. In fact, it is neither absolutely liver nor gland, but

152

ANATOMY.

iiutrimental matter, which, during the metamorphosis, particularly
during the pupa sleep, is absorbed like the fat of the lethargic mammalia
during their hybernation. But the degree of reference the function of
the liver has to the preparation of the fat is sufficiently well known
from the example of the lethargic* mammalia, therefore the above opi-
nion, when we consider the small size of the biliary vessels supplanting
the liver, or the treatment of these vessels as kidneys, a view also
recently promulgated, may possibly have many supporters.

The nature of this fatty body is in so far uniform that it consists of
shreds, which upon microscopic investigation are found to be constituted
of small globules of animal aboriginal matter. This is the only cha-
racter this fatty mass presents upon the closest investigation ; exteriorly
it is surrounded by delicate membranes, which consequently may be
compared to the membranes of the cellular texture, but the lens does
not show it very distinctly, from its transparency, delicacy, and tex-
turelessness. Ramdohr, who considered the fatty mass as plastic lymph,
obtained from experiments upon that of the Ga&tropkaga qucrcus
the following result : — it melted in boiling water, effervesced with
sulphuric acid, at the same time smelling like burnt horn, and in cold
water was precipitated in white flocks; heated over a lamp it hardened
into a white firm mass, swelled up upon the application of greater heat,
and then burnt away, dispersing a stinking vapour. According to my
experiments, made with the large flabby fatty mass of Cossus ligni -
perda , it melted in a spoon over a lamp into a perfectly clear trans-
parent yellow liquid, which paper instantly absorbed, and was rendered
transparent by it like fat ; it had a peculiar smell, like that of freshly
opened caterpillars ; its taste was fatty and insipid. Upon increased
heat it boiled up in bladders but did not become firm, or else it consumed
to ashes. Laid fresh in hot water it became softer, more transparent,
and particles of it floated on the top like oil.

These very contradictory results tend at least to prove that the fatty
substance in different insects consists of very different constituents,
which is the more striking as both experiments were made from insects of
the same order, in which they even approach very near each other. Pro-
bably Ramdohr’s caterpillar had been long immersed in spirits of wine,
thus consequently, and by the additional influence of heat, the fat parts
had separated, and only the cellular portion of the enveloping mem-
branes remained.

The entire fatty mass forms a reticulated meshy web, which enve-

THE ORGANS OF DIGESTION.

153

lops the interior organs and completely fills all portions of the cavity
not occupied by them. In larvae the threads and laces of this net are
larger and more ragged, particularly in the fat larvae of the crepus-
cular and night moths. The nearer it approaches the pupa state the
larger are the proportions of this substance ; but as soon as the insect
becomes fully developed this material loses its size, and it becomes a
broad, delicate, laced web. It is consequently during the pupa state
that the greater portion of this substance becomes absorbed, whereby
the shreds shrink up, the delicate membrane becomes narrower, and
thus the preceding coarse shreds become delicate and fine laces. In this
shape the fatty mass not merely represents the rete of the vertebrata,
but actually becomes it, for it is the envelope of the intestines, and in
conjunction with the air vessels it supports and fixes them. Thence is
it that earlier (Malpighi) and more modern (Cuvier) anatomists have
called it the net of insects. It is scarcely necessary, after such facts,
to adduce other reasons in opposition to the above disputed opinion that
this net is the liver of insects ; whoever has but watched the develop-
ment of a single butterfly, indeed, whoever shall but have compared
an opened caterpillar with an opened moth, to him it will be evident
that the fatty mass cannot be the liver.

Chemical analysis has as yet contributed nothing towards the
removal of the difficulties which still involve the different views upon
this subject, although a careful investigation would most certainly settle
the dispute. In ants* and the cochineal insect fat has actually been
found, and this consequently may certainly contribute to support the
adoption of the opinion of this substance being found in all other insects.

§ 116.

III. THE BLOOD VESSELS.

We shall find the vascular system just as simple and uniform in
insects as we have found their digestive apparatus complex. A vessel
which passes along the back from the head to the anus constitutes the
only blood vessel to be discovered in insects. That this canal is a true
blood vessel, and indeed an artery, is proved by its regular contraction
and expansion, which is very easily perceived exteriorly in transparent
thin-skinned larvae. Malpighi, its discoverer, considered it as such,

* Compare Gmelin, Handb. d. Theor. Chemie, vol. ii. Div. i. p. 469, No. 24, and
p. 508. No. 1 ; 2nd Div. p. 1473, &c.

154

ANATOMY.

and has described it as a great pulsating * vein. Subsequently to him,
the other great entomotomists, Reaumur, Swammerdam, Bonnet, De
Geer, have recognised the same organ, and concur with him in repre-
senting it as a simple and wholly closed vessel. Even the very cautious
Lyonnet can consider it as nothing else ; but he described the lobes of
the dorsal vessel in greater detail, and has figured them more accurately
than any of his predecessors. In recent times Cuvier, in his “ Com-
parative Anatomy,” has repeated the descriptions of earlier anatomists,
and even after this organ had been subjected to the most painfully
patient investigations by Herold and Müller, its true structure has not
yet been ascertained. Carus f at last discovered the motion of a fluid
not only in the dorsal vessel but also in other parts of the body, and
shortly after him Straus — Durckheim recognised a structure of the
dorsal vessel, which had been previously overlooked, which so entirely
agrees with the insect type of organisation, that no doubt can be enter-
tained of the correctness of his observation. My attention being drawn
to it by Straus’ communications, I made investigations upon the
structure of the heart in several insects (for example, in the larva of
Calosoma sycophanta , Lamia cedilis, Termes fatalis , &c.), and I have
distinctly seen the valves and apertures mentioned by him.

§ 117.

According, therefore, to these most recent observations, the dorsal
vessel (PI. XXII. f. 8 and 9.) is a thin canal composed of a delicate
membrane, it is largest in the abdomen, and gradually decreases to-
wards the head. In the abdomen it has on each side several apertures,
as well as lateral muscular lobes, whereby it is attached to the back ;
where it enters the thorax it bends downwards (the same, f. 8. b.) that
it may pass through the narrow, more deeply situated opening into its
cavity, and then pursues its course above the oesophagus to the head,
where it terminates with a small orifice. The number of the lateral
apertures appears to vary (the same, a , a, a). Straus found eight in
Melolontha , I could observe but four on each side in the larva of Calo-
soma. According to Muller’s description of the heart there appears to

* Compare his Dissert. Bombyce. Lond. 1669, 4to. or his Collective Works, Lugd.
Bat. 1687, 4to., vol. ii. p. 20.

t Entdeckung eines einfachen, vom Herzen aus bleschleunigten Kreislaufes in den
Larven netzflüglichcr Insekten. Leipz. 1827. 4to.

THE ORGANS OF DIGESTION.

155

be but one aperture in Pkasma , which also has but one pair of lateral
muscles. By means of these apertures the heart is divided into so
many chambers, for behind each opening there are valves which separate
the preceding space from that behind the opening, so that in Melo-
lontha there are eight (PI. XXI. f. 1 — 8.) such consecutive chambers.
The first, which lies close to the dorsal sheath of the last abdominal
segment, is the smallest, and consists of one heart-shaped bag, which
in front, towards the head, has an opening like a slit. The lips of this
aperture consequently form the anterior side of the bag and close it, if
blood, pressing forward from within, does not part them. The blood
enters it through two small apertures, which likewise lie in front upon
each side of the bag, but it cannot flow back through the same openings,
for a half-moon-shaped valve which is affixed within the cavity of the
bag beneath the aperture closes upon it, and thus, when the heart con-
tracts, the blood must necessarily pass through the anterior opening.
This first and most posterior chamber of the heart is succeeded by
another in front, formed very similarly, but longer and more cylindrical,
and which has also an aperture behind, viz. the anterior one of the first
chamber. It is through this that the blood passes from the first cham-
ber to the second when the heart contracts, and upon its dilatation
blood pours into the chambers through the two lateral anterior open-
ings. Thus, therefore, each chamber is always provided with blood,
for the blood streams from one chamber to the other, beginning at the
posterior, when that wffiich has been received through the lateral open-
ings from the cavity of the abdomen passes on by their successive con-
tractions. We will explain how this contraction (systole) and dilata-
tion (diastole ) of the heart take place after we have said a few words
upon its structure.

§ 118.

According to Straus, two membranes are observed in the heart, the
exterior of which is smooth, dense, and longitudinally fibrous, conse-
quently muscular. It is this which forms the above-described valves,
for at the two margins of each lateral aperture it bends inwards. The
posterior return forms the inner valve of that opening, and the anterior
return the partition of the chamber, or both the anterior ones form the
lips of the anterior opening. Both valves, as well as the entire internal
lining of the heart, are covered with a transversely folded and looser

156

ANATOMY.

layer of muscle, which is still thicker and stronger in the middle of
each chamber. Perhaps both membranes are but the different layers
of one muscular membrane, and then we might, by the analogy of all
blood-vessels, entertain the idea of the presence of an innermost struc-
tureless mucous membrane, which escapes observation by its delicacy.

It is from the presence of these muscular layers that it is possible for
the heart to contract and dilate. By both membranes simultaneously
contracting the heart becomes straitened, and this distends again as
soon as the membranes become flaccid after the contraction, when the
muscles of the lobes contract themselves.

§ 119.

To the posterior portion of the dorsal vessel which we find provided
with apertures and valves, and which we must consider as the true
heart, several triangular, flat, membranous muscles are affixed, the
points of which pass on to a dorsal plate of the abdomen, and there
attach themselves (PI. XXII. f. 9). If these wings (flügel) of the
heart, as they are called, are short, or consequently of the shape of an
equilateral triangle, other muscles of the form of a band originate at
the apex of this triangle, and pass in a diverging direction from each
other, and insert themselves upon the abdominal plate, where this
becomes membranous ( Lamia cedilis ). Generally, however, the wings
are so long as not to require the muscles of attachment ( Melolontha ,
&c.), and they then take the shape of a very acute triangle. The
conjunction of these muscular wings with the heart, which they merely
retain in its place, is very intimate, without its being possible to say
where ; whether it be by fibres passing from these wings into those of
the heart, or whether the membrane of the heart sends forth lateral
folds it is impossible to say. They lie in a row upon the two opposite
sides of the heart, precisely where the anterior aperture of each cham-
ber is found. They pass over these apertures, the fibres attaching
themselves to a small membranous arch which crosses these orifices
transversely ; consequently, in front of each orifice, there is a small
semicircular hole in these wings, which are thus prevented from inter-
rupting the flow of blood.

These wings are wanting to the dorsal vessel of the Libellula, and
Phasma has but one pairin the sixth abdominal segment. Besides
this we find a pair of muscles passing from the posterior margin of the

THE ORGANS OF DIGESTION. 157

heart, their apex being attached to the last abdominal segment and the
colon, which has not yet been observed in other insects *.

§ 120.

The anterior portion of the dorsal vessel which passes through the
thorax to the head, and which is not furnished with apertures and
muscles (PI. XXII. f. 8. c), may be called the aorta if we call the pos-
terior portion the heart. The part which may be considered as such
commences where the dorsal vessel bends near the thorax to pass into
its cavity, for from here the apertures and muscles are wanting. This
bend is greater or smaller, according to the size of the posterior par-
tition of the thorax, largest doubtlessly in the petiolated Hymenoptera
or the Diptera, whose thoracic cavity is entirely separated from the
abdominal cavity by the metaphragma. When the aorta arrives in the
cavity of the thorax its course becomes then direct as far as the head,
constantly keeping the central line, and accompanying the here straight
oesophagus or stomach, and frequently united to it by a cellular mem-
brane or the fatty substance. When there is a free and moveable pro-
thorax it passes likewise into this through the common opening, or more
rarely (as in Gryllotalpa f) through a small aperture in the meso-
phragma (PL XI. No. I. f. 7- «)> and here still accompanies the oeso-
phagus as far as the head. Here, close to where the oesophagus bends
down to the mouth, consequently behind the cerebrum, the aorta sud-
denly ceases with a somewhat distended orifice, without previously
sending forth any smaller vessel; in other instances it divides in a fork,
each branch of which bends laterally, and terminates after a very short
course likewise with a free orifice; or, lastly, we find three short, equal,
radiating branches, each open at the extremity (for example, in Gryl-
lus hieroglyphicus, Klug. J).

§ 121.

We thus conclude the description of the blood-vessels of insects.
The most laborious and patient endeavours of Entomotomists to discover
other vessels remained unrewarded, until Joh. Müller discovered a union
of the ovaries with the aorta §. We shall treat in greater detail of this

* Comp. J. Müller, über das Rückengefäss, in Nova Acta. Med. Nat. Car. vol. xii. pars
ii. pp. 576 and 586.

f Ibid. p. 596. + Joh. Müller, ib. p. 613. § Ib. p. 613.

158

ANATOMY.

connection lower down, in the Chapter where we speak of the sexual
organs ; but we must defer hinting at their hypothetical use, as well as
of the doctrine of a circulating system in insects, until the following
division, to which we consequently refer.

§ 122.

IV. OF THE ORGANS OF RESPIRATION.

We shall find the respiratory organs of insects as complex and per-
fectly developed, as we have found their blood-vessels simple and
imperfect. The relations between these systems appear to be in them
completely reversed, for the air-vessels intersect the insect body as
multitudinously as we find the blood-vessels do in the superior animals.
We cannot here show whence this transposition of the usual relations
proceeds, nor how an entirely different structure can produce a similar
result, this belongs to Physiology ; we are here required merely to
explain the structure and distribution of the air-vessels, and their
external orifices. Our subject thence divides itself into two portions ;
the first of which treats of the exterior organs attached to the respira-
tory organs ; and in the second, we shall describe the internal air-
vessels themselves.

§ 123.

A. Exterior Organs of Respiration.

The exterior organs of respiration which are found upon the surface
of the body, are of a triple character, namely, spiracles, air tubes,
and branchije. The first are easily distinguished from the last, by
the presence of an orifice that opens directly into the tracheae, whereas
the branchiae are membranous leaves, throughout which tracheae are
dispersed, without opening anywhere.

I. The spiracles ( spiracula , stigmata ), which are the most fre-
quently found of all the exterior organs of respiration, appear as
incisions or small round openings at the sides of the segments of the
body, which are sometimes surrounded by a peculiar oval horny ring ;
or are encircled by merely the usual integument of the body, without
any apparent distinction. Both kinds of structure are supplied with a
muscular apparatus which opens and closes the aperture, so that the
insect can either open it to receive air, or close it against it. We shall
proceed with a description of their various forms, after this short indi-
cation of their differences.

THE ORGANS OF RESPIRATION.

159

Some which are never free, but lie concealed beneath portions of the
horny integument, have no exterior horny ring, but a double-lipped
incision, the lips of which are formed by a thickened margin fringed with
short hair. This structure is very apparent in the large spiracle which
lies in the uniting membrane of the pro- and mesothorax, and parti-
cularly in Gryllotalpa (PL XI., No. 1, f. 2, a. a .), where, by reason of its
length, it is very distinct. The horny lips are connected at their corners
by a kind of joint, but in Gryllotalpa the lower corner of this incision,
which lies near the anterior coxae, is broader and more prominent; and the
corner of the exterior lip projects beyond the opposite interior one, form-
ing a kind of covering, thus preventing the influx of improper substances.
The entire spiracle is closed by means of a small muscle, which, origin-
ating from an inner horny projection of the lower corner of the lip,
inserts itself in two horny half-rings, which surround the commence-
ment of the tracheae. The orifice is opened or shut by the contraction
or dilatation of this muscle.

Other spiracles, which besides the lips possess an oval horny margin,
present a somewhat more complicated structure. The horny ridge
(PI. XXIII, f. 1- — 3, a,) is no distinct part, but merely the raised edge of
the integument surrounding the spiracle ; it thus forms an exterior
ring, to which the lips of the incision are attached. These lips (the
same b. b .) stand at the base of the ring, and are frequently covered
upon their external surface like it upon its internal circumference,
with sculptured horny scales ( Oryctes nasicornis ). Where they meet
they again form a small projecting margin which, as in the former kind
of structure, is surrounded by a fringe of fine hair. The corners of
the lips lie close to the inner margin of the exterior ring, so that the
true opening, upon the lips being closed, appears as the diameter of the
oval ring. The closing apparatus of these spiracles is very complicated.
The ends of the incisions, namely, or the corners of both lips, are pro-
longed inwardly into a point (the same, c. c.), to which two triangular
horny plates are so attached, that one angle of the triangle with the
projecting point, and the second with the opposite one of the other horny
plate, form a joint, but the third remains free. From the last, as well
from the sides of the triangle which are applied to each other, a flat
muscle originates (the same, e .) which, when it contracts, brings the
free points of both triangles together, but those which stand in connec-
tion with the inner points of the corners of the lips, it separates from
each other ; thus is the incision closed : but when the muscle again

160

ANATOMY.

relaxes, it re-opens. We must observe, at the same time, that a bag-
shaped expansion of the tracheae originates from the circumference of the
spiracle, and narrows towards the latter, in a funnel shape. By means
of the tracheae arising from the point of the funnel, the whole expansion
is drawn backwards, so that the axis of the funnel stands obliquely to
the axis of the tracheae ; upon the inner side of this funnel, or that
part next to the ventral cavity, the just described apparatus for the
closing of the spiracle lies (see PI. XXIII, f. 1 — 3). Such spiracles are
found only upon free or slightly covered parts of the body, for example,
under the elytra of many beetles.

A third form of the spiracles is distinguished from the preceding by
the want of lips. In very small and round spiracles, the opening is free
(for example, in the Lamellicornia), or at most covered with short hair
upon their inner margin, and the entrance into the tracheae is only
rendered difficult by the obliquity of its axis to that of the spiracle.
In larger oval spiracles, the margins are occupied with stronger plumose
spines, or hairy tufts (PI. XXII. f. 10), and these resist extraneous
substances still more forcibly. The air is purified through these as
through a sieve, and all prejudicial substances are caught there. This
structure is very distinct in the large spiracle of the first abdominal
segment of the male Cicada, as well as in the dorsal spiracles of the
water beetles *.

The fourth and last form of the spiracles is that observed in the
larvae of the Lamellicornia. In these the very minute spiracle appears
at first view to take a circular shape, and upon closer inspection it is
found to consist of a broad margin and a concentric middle space,
which beneath breaks through the margin and connects itself with the
surrounding integument. This margin, which is often ornamented
with distinct sculpture (PI. XXIII. f. 4. a, a ,) Sprengel considered as
a half moon-shaped opening, occasionally closed by a sieve, when the
sculpture of the margin was cribriform, or by toothed processes, when
the sculpture took that figure, opposite which the inner round plate lay
and assisted to close it. Treviranus t opposes this view of it, and asserts
that the spiracle is entirely closed, but that minute ramifications of
tracheae are spread upon its internal superficies, and imbibe the air,

* See Carus, Analekten zur Naturwissensch. Dresden, 1829. 8vo. P. 187. PI. I,
f. 18. And Sprengel, Commentar. &c. Plate II, fig. 23; and Plate III, fig. 29.

■f Das Organische Leben, neu dargestellt. Bremen, 1831. 8vo. Yol. I. p. 258.

THE ORGANS OF RESPIRATION.

161

as in the branchiae, through the plate of the spiracle. Both were mis-
taken, for these spiracles have likewise a central aperture, which leads
directly into the stem of the tracheae. This orifice, which is a small
transverse incision, lies in the central round plate (PI. XXIII. f. 4. c),
and is very small in proportion to the entire spiracle, and may there-
fore be easily overlooked ; but Kaulfuss, in his drawings to SprengeFs
Treatise, has everywhere indicated them. The exterior margin is,
however, by no means perforated, but merely covered with sculpture,
just like the exterior oval horny ring. I consider this margin therefore
as the pre-formation of the subsequent oval horny ring, the central
plate, however, as the two lips of the here still smaller incision. Inter-
nally the main stem of the trachea is observed to originate from the
circumference of the aperture, a distinct proof that the incision is its
orifice (PI. XXIII. f. 4., d. d.).

§ 124.

After noticing the form of the spiracles, the next most important
subject is their situation in the body, which is tolerably uniform in the
several orders, but there are a few divarications from it, which we may
here briefly indicate.

In the Coleopter a each segment of the body has a spiracle, or, to
speak more correctly, upon the boundaries of every two segments
we find one. The first, and generally the largest spiracle, is seated
in the uniting membrane of the pro- and meso-thorax, more closely
approaching the exterior and lower margin of the former, where it gene-
rally remains when those two portions of the body are separated. The
second spiracle lies in a very similar situation, namely, between the
meso- and meta-thorax, but it is so concealed by the elytra that it can
be discerned only upon very close investigation. It is then observed
between the two horny plates which we called above (page 81) the
anterior and posterior wings of the scapulae. In a state of repose the
two plates lie closely together, and thereby completely cover this spi-
racle ; but upon the expansion of the wings during flight, when the
body filled with air distends, this spiracle also quits its concealment,
that it may, like the rest, allow air to flow in and out. The concealed
situation of this spiracle explains how it has been overlooked, particu-
larly as we observe none in the similarly named segment of the larvae.
Straus first observed it, and has exhibited it in the cockchafer and in
others. The third spiracle lies between the meta-thorax and the first

162

ANATOMY.

abdominal segment ; it is frequently minute and indistinct, but occa-
sionally, as, for example, in the Capricorn beetles, it is very large, indeed
larger than the first. The following spiracles, six or seven in number,
lie always between every two of the successive abdominal segments, so
that the two last segments alone have no spiracles ; we thus obtain ten
spiracles upon each side, twenty together, a typical number which is
never exceeded, but often also not attained.

In the Orthoptera the spiracles are not differently situated. The first
which is in the connecting membrane between the pro and meso-thorax is
very large, particularly so in Gryllotalpa (PI. XI. No. I. f. 2. a, a) ;
the second, between the lower wing of the scapula and the dorsal piece
is here quite free and uncovered (the same, fig. 8. ß). The third
spiracle, which properly should lie between the meta-thorax and the
first segment of the abdomen, approaches more closely to the latter,
and lies in Gryllus , F. (Acrydium, Lat.) in a half moon-shaped hollow,
which upon one side is partly closed by the projecting cover-shaped
margin. All the succeeding ones are placed in a similar situation,
namely, at the lower margin of each dorsal plate of the abdomen. In
the Blattaria, on the contrary, the spiracles are always placed in the
connecting membrane between two segments, and precisely where the
dorsal and ventral plates meet ; the same is the case in Forficula ; in
these also the third spiracle lies at the anterior edge of the dorsal plate
of the first segment of the abdomen, where it is very distinct although
but small.

In the Hemiptera, which, by the structure of their thorax, approach
closely to the Orthoptera, the first spiracle likewise lies in the connect-
ing membrane between the pro- and meso-thorax ; it is tolerably large,
and narrow, and is only apparent upon the removal of the pro-thorax.
A second spiracle is found between the meso- and meta- thorax, and
resembles the former in being a rather long, half moon-sliaped, or
straight incision, and is covered by a posterior projection of the margin
of the meso-sternum. This spiracle consequently cannot be seen from
the exterior from the preceding projection (PI. XIII. No. 5. fig. 2. ß)
lying over it, and above it is concealed by the elytra. The succeeding
spiracles are in these insects, as in the Orthoptera, more approximate
to the ventral segments, a spiracle being placed in each abdominal seg-
ment, vrhereas by analogy it should lie between every two segments.
In the male Cicada the first is very large, free, and always beset with
strong setae at the margin, the following are smaller and indistinct.

THE ORGANS ÖF RESPIRATION.

163

Kirby and Spence describe large lateral spiracles in the bugs., lying
between the meso- and meta- thorax, but I could perceive in our bugs
( Pentatoma rufipes and P. hämorrhoidalis) depressions only at these
parts ; but if the acute posterior margin of the prosternum, which lies
precisely in this cavity, be removed, the spiracle is observed very dis-
tinctly beneath it. In Belostoma a very distinct spiracle is found at
the posterior margin of the pleura, consequently between the meta-
thorax and the abdomen, which, however, appears to belong to the
first abdominal segment, because in the bugs the spiracles lie always in
the ventral segments themselves, and, indeed, at the exterior margin
of the ventral plates, and not, as in the beetles, beneath the wings and
the elytra.

The Neuroptera alone, of the remaining orders, have a distinctly
separated pro-thorax ; it is here therefore that we must notice them.
Semhlis displays two distinct pairs (PI. XIV. No. 3. f. 2. 4. a and /3,)
of spiracles in the thorax, the first between the pro- and meso-thorax,
and the second between the meso- and meta-thorax. Whether there
be a third pair between the meta-thorax and the abdomen I could not
clearly perceive either here or in Myrmecoleon , but in the dry speci-
mens examined by me there appeared to be incisions. The two first
pairs lie, also in the ant-lion, exactly in the same place. Panorpa dis-
plays two pairs of spiracles in the thorax and five pairs in the abdo-
men ; the two first lie between the pro- and meso-thorax, and between
the latter and the meta-thorax, and display themselves as small brown
points. In the abdomen they are placed, as in all Neuroptera, in the
connecting membrane of each pair of segments, closely in front of that
to which they belong.

In the Dictyotoptera, as those most closely allied to the preceding
order, with the exception of the Libellulce and Termites , they are, from
their minuteness, difficult to investigate. The Libellutce have two pairs
of spiracles in the thorax, one pair being between the pro- and meso-
thorax, each of which, however, is covered by a small scale originating at
the posterior margin of the pronotum ; the second pair is seated between
the meso- and meta-thorax, at the sides of the thorax. The former are
long, somewhat bent incisions ; the latter very small, ovate, two-lipped
spiracles. I have observed none between the meta-thorax and the
abdomen. It has also been said that they have no abdominal spi-
racles. But Reaumur and Sprengel admitted their existence in those

m 2

164

ANATOMY.

larvae which live constantly in water, but Kirby and Spence * again
denied it, their attention being probably drawn to it by Roesel’s |
observation of their respiration through the anus. This intestinal
respiration Suckow X has confirmed by showing branchiae in the colon,
and thus proved the entire inutility of spiracles. But in the perfect
insect there are seven pairs of spiracles upon the central abdominal
segments, which are covered however by the margins of the dorsal
plates lapping over them as they lie in the soft connecting membrane.

In the Termites the spiracles are found in analogous situations, but
those of the abdomen are so small that they are seen with difficulty.

The remaining three orders very closely agree both in the structure
of the thorax as well as in the situation of the spiracles. All possess
our in the thorax, two of which are upon the limits of the proj
thorax, between it and the meso-thorax, and the other two lie between
the meso- and meta-thorax. In the Hyrnenoptera , in which the thorax
consists of a hard horny case, and the segments are closely united
together, the posterior pair of spiracles lie upon the meta-thorax itself,
whereby they distinguish themselves from all the other orders ; besides
which the anterior pair of spiracles are covered by a small scale-shaped
projection of the posterior margin of the pronotum, which scale ( tegula ,
comp. § 77-) lies precisely beneath the anterior wing, and is very
readily recognisable in the wasps. In PI. XII. No. I. f. 1., wherein the
thorax of Cimbex is represented, the letters a and ß point out the situa-
tion of the spiracles, as also in the same plate, No. II. f. 2. in the thorax
of a Scolia. The spiracles of the Lepidoptera are distinguished only by
possessing a narrow, scarcely perceptible, horny ring, which lies con-
cealed beneath the hair (PI. XIII. No. IV. f. 2. shows at a and ß,
where they are placed.) In the Diptera they appear as short, some-
what compressed tubes, particularly the first, between the pro- and
meso-thorax, as is showm in PI. XIV. No. I. f. 2. in Tabanus, and
No. II. f. 2. in Myopa. A similar uniformity exists in the situation
of the spiracles of the abdomen, for they always lie in the connecting
membrane of the segments, and are covered by the projecting margins
of the dorsal plates.

The numbers of the spiracles are thus shown in their situation. If

* Introduction to Entomol., vol. iv. letter xxxviii.

f Insectenbelustigungen, 2 band. Wasserinsecten der 2 classe, Taf. II. and III.

X Heusing. Zeitschr. für die Org. Physick. 2 band. 2 lift. S. 36, &c. PI. I. and II.

THE ORGANS OF RESPIRATION.

165

we call to mind also the general law which makes the insect body to
consist of thirteen segments, whereof one forms the head, three the
thorax, and nine belong to the abdomen, the number of the spiracles
is readily ascertained. The thirteen segments have namely twelve
connecting membranes, of which the first only (between the head and
pro-thorax) and the last are never supplied with spiracles, consequently
there cannot be more than ten on each side at most. But as the
number of the abdominal segments considerably varies, it consequently
frequently happens that there are fewer spiracles. I have observed
twenty in the water-beetles ( Dyticus ). According to Degeer and La-
treille *, the locusts and Lepidoptera display as many : the Lamelli-
cornia and Cerambycina possess eighteen. Many Orthoptera , the Ter-
mites, and Libellulce possess the same number. The Hymenoptera have
but seven distinct abdominal segments, the last of which, according to
the general rule, bears no spiracle ; in general they possess sixteen :
Panorpa has fourteen ; many Diptera still fewer, as but five or six
distinct abdominal segments are perceived in them.

§ 125.

II. The air tubes are absolutely nothing but elongated spiracles,
although they are not always found, where the spiracles are placed.
They are only observed in insects which live in the water, namely, in
the larvae of many Diptera and some water-bugs ( Nepa , Ranalra),
and are placed either at the first or the last abdominal segment. They
here appear as either long or short horny tubes, which pass directly
from the general integument of the body, being open at the end, and
within the orifice they are surrounded by simple or plumose setae, or
else entirely unprovided with them.

The larva of the common gnat ( Culex , PI. III. f. 3) is very gene-
rally known as possessing this organ, which is placed obliquely at the
last abdominal segment. Simple branches of the tracheae pass into
this tube, opening where it terminates. The end of the tube is
surrounded by setae, and these support the animal upon the sur-
face of the water when it places itself there to breathe. In the pupa
state the tube at the end of the abdomen disappears, and instead of it
two bent tubes project from the thorax between the pro- and meso-

* P. A. Latreille sur quelques Appendices du Thorax des divers Inscctcs. In Mem. du
Museum d’Hist. Naturelle, torn. viv.

166

ANATOMY.

thorax (Ph III. f. 4). The majority of the larvae of the genera most
closely allied to this gnat possess no such air tube, but true branchiae
or gills, yet the larvae of Chironomus * have likewise two conical air
tubes upon the anal segment (PI. III. f. 5) ; besides which they are
easily distinguished by a more elongate vermiform shape +, as well as
by their blood red colour, from the true larvae of the Culicidce. A
similar structure is found in the larvae of Stratiomys ; in them the
entire last segment of the abdomen is elongated into a tube, and at the
aperture of the tube it is provided with a wreath of plumose hairs
placed in the form of a star. This coronet, which is much larger than
that of the larva of Culex , likewise supports the much larger creature
upon the surface of the water when it goes thither for fresh air ; and it
likewise takes air bubbles, which are inclosed by the setae, down with it
to the bottom of the stagnant pools which it inhabits, as a provision
for its next inspiration J. The larvae of the genus Eristalis display
a considerably longer anal air tube ; in these also the last joint is
extended into a membranous tube, in which a second narrower and
corneous one is contained, which at its open end is provided with a
similar crown of hair. It is into this tube that the two branches of the
tracheae pass after having united into one. The thick, white, cylin-
drical larva which lives in the mud of pools, in sewers, and in excre-
ment, directs this tube to the surface of the water, which hangs there
by means of the above-mentioned setse, while it itself lies tranquilly at
the bottom, or else continues feeding. If the water should rise, for
example, after rain, it lengthens this tail by pushing the inner tube as
far out as is requisite. This elongation can be extended to several
inches, whereby the length of the tail exceeds several times that of the
body. For the expiration of the air thus received two other very short
air tubes are placed upon the first segment of the body, directly behind
the head ; the anterior ends of the above described main stem of the
tracheae pass into these after having previously, as well as the posterior
ends, become united by means of a transverse branch.

We also observe anal air tubes in the genera Nepa and Ranatra, but
which are distinguished from those above described in the first place by

* The larvae have gills (branchiae), as I have recently observed (Author, MS. Note).

f These larvae were formerly considered as a genus of annelides, and were called
Branchiurus. See Oken’s Zoologie, 1 band. s. 383. Taf. 9., and Viviani Phosphor. Maris,
3. 13, 14.

$ See Swainmerdamm, Biblia Naturae, PI. XXXIX. f. 1 — 3.

THE ORGANS OF RESPIRATION.

167

their number, two always being present, and secondly by their form,
they being simple horny tubes unprovided with setae at their end.
In Ranatra they are as long as the body, and in Nepa half its length.

It seems to be a very general law, that the situation of the spiracles
should be at the posterior end of the body, not only in the Dipiera , but
also in all larvae which live in water and are unprovided with branchiae.
With respect to the larvae of the Dipt er a, those yet investigated have
their spiracles in that situation: for example, the flies and CEstridce.
The larvae of the water-beetles likewise (for example, Dyticus and
Hydrophilus ) have their spiracles at the anal end, contiguous to the
anus, and have none at their sides, although Sprengel describes and
even figures them there *.

§ 126.

III. gills, or branchiae» — This third description of the organs
of respiration is particularly distinguished from both the others by its
want of apertures to admit the air into the tracheae. The gills are
processes of the epidermis in the form of hair or leaves, in which
delicate tracheae ramify in every direction. These vessels imbibe the
air mixed up mechanically with the water, and conduct it to the main
stems concealed in the body, by means of the branches of which it passes
to all the internal organs. Through this arrangement insects pro-
vided with gills do not require atmospheric air, they consequently do
not rise to the surface of the water, but live constantly in it concealed
among water plants.

The branchiae may be separated into two divisions, by their forms;
the one being delicate and slender, resembling hair, while the other
is broad, thin, and lamelliform.

The hair-shaped branchim seldom appear singly, but generally in
approximate fasciculi, which are formed by either the ramifications of
one or of several main stems (PL III. f. 6.), or by filaments radiating
from one point (the same, f. 10). The epidermis of these processes is
exceedingly delicate, as well as the small silvery tracheae enclosed by
it. This kind of branchiae is the most usual and general ; it is found
particularly in the larvae and pupae of the gnats.

The lamellate branchiae are found only in the Dictyotoptera and the
Neuroptera , and appear as broad or pointed lanceolate leaves, and are
found on each side of each abdominal segment, or only at its end.

* Commcnlar., p. 37. No. xx. PI. II. f. 20.

168

ANATOMY.

Several, or at least two leaves, are found at each place, so that each
segment of the body has never less than four branchial leaves. They are
generally uniform, but an instance is known ( Ephemera fusco-grisea.
De Geer* * * §,) in which one of the branchiae is lamellate and the other
is a fasciculus of filiform ones.

If we look to the orders in which branchiae are found, we shall
speedily see that they are not rare, and, indeed, that the majority of
larvae which live in water breathe by means of gills.

The following are the genera whose larvae thus respire : —

Among the Coleoptera we find hairy branchiae in the larvae of the
whirlwigs ( Gyrinus f), which rise from the sides of each segment, and
clothe the body as simple, tolerably stiff, hairy processes. The closely
allied Dyticus have no gills, but spiracles, which lie contiguous to the
anus; the larva of Hydrophilus piceus likewise breathes through
spiracles thus placed, but the larva of Hydrophilus Caraboides, has,
according to Roesel’s figure J, ramose branchial fasciculi on each abdo-
minal segment.

The Orthoptera never live in water either as larvae or as perfect
insects, they have consequently only spiracles as the exterior organs of
respiration.

Many of the Hemiptera, both in their larva and perfect state, live in
water, but branchiae have never yet been observed in them. Both young
and old, when they wish to breathe, come to the surface of the water,
and receive air through the spiracles. Nepa and Ranatra have air
tubes, which we have mentioned above.

Whereas in the orders of the Dictyotoptera and Neuroptera the
branchial apparatus is very general. In the first of these orders, the
larvae of the Ephemerae and Libellulce live constantly in the water, and
have branchiae. In the larvae of the Ephemerae they lie at the sides of
the body, four upon each segment, and they consist of small leaves of
various forms. In Ep. fusco-grisea one branchia is a leaf, and the other
a fasciculus ; in Ep . vulgata § both are leaves, very narrow, and clothed
at the margin with long fine hairs. The branchiae of the larvae of the
Libellulce are not placed at the sides of the abdominal segments, but
upon or within the last segment ; and in Agrion they form three large

* De Geer, M6moires sur les Insectes, vol. ii. part ii. p. 29. PL XVIII. f. 3.

f lb., vol. iv. PL XIII. f. 16— 19.

X Insectenbelustigungen, vol. ii. Wasser-Insectcn d. Erst. Klasse, p. 32. PI. IV.

§ De Geer, ib. PI. XVI. f. 3.

THE ORGANS OF RESPIRATION.

169

clavate leaves fringed at the margin. The larvae of Mschna and Libel -
lula breathe through fasciculated branchiae,, which lie in the colon.
Thither proceed the terminal ends of the four main stems of the
tracheae ; they transpierce the membrane of the colon, and hang as thick
fasciculi within the cavity of this organ * * * §. As the creature imbibes
water by means of it, and thus again rejects it, it helps to assist it in
swimming, which, without this auxiliary aid, it would find it difficult to
effect, from its deficiency of other swimming leaves. Other larvae swim
by means of the branchial leaves, which move with an incessant
alternating vibration.

Among the Neuroptera we are acquainted with the families of the
Phryganodea and the Semblodea, whose larvae inhabit water. Both
breathe during this state only through branchiae, which in the former
consist of two leaves placed on each side of each abdominal segment,
but varying in form according to the genera, but in the latter they
appear as simple or plumose, tolerably long processes, which consist of
several joints, becoming gradually acuminate, upon the under surface
of which the tracheae ramify, protected by two rows of setae f.

Branchiae seem very general in the family of the gnats, among the
Diptera , as they are found not only in the larvae but also in the pupae.
This is the case in the genus Chironomus, whose larvae described above
breathe through exterior tubes, but whose pupae are furnished with
two radiating fasciculi of branchiae at the thorax (PI. III. f. 6.). These
branchial fasciculi are seated close to the spot where later the first spiracle
of the thorax is found, namely, between the pro- and meso-thorax.
The same is the case in the genus Simulia ; the former has air tubes
at the anal end as well as at the thorax, the latter two large branchial
fasciculi between the pro- and meso-thorax (PI. III. f. 9 and 10 J). The
reversed relations obtain in the genus Anopheles , whose larva, described
as a remarkable water animal, first by Goeze §, and afterwards by
Lichtenstein ||, but which G. Fischer H ascertained to be the larva of this
gnat, bears hairy branchiae at its anal end, but whose pupa is provided

* Suckow in Heusing., vol. ii. part i. p. 55, &c. PI. I. and II.

f lb., p. 27. PL III. f. 24.

X Compare Thon’s Archiv, der Entomologie, vol. ii. no. ii. PI. II.

§ Beschäftigungen der Berliner Gesellsch. Naturfors. Freunde, vol. i. p. 359. PI. VIII.
|| Wiledemann’s Archiv, für Zoologie und Zootomie, vol. i. No. i. p. 168. PI. III.

G. Fischer, Sur quelques Dipteres de Russic. PL I. f. 1 — 16.

170

ANATOMY.

with two curved air tubes between the pro- and mesothorax (PI. III.
f. 7 and 8.)

Among the Lepidoptera but one caterpillar, that of Botys stratio-
talis has been observed to possess branchiae *. In this they consist of
delicate small hairs which clothe the whole body, but particularly
laterally, in the vicinity of the future spiracles, they stand in fasciculi.
The tracheae are observed in them as glittering silver-white threads.
The caterpillar lives constantly in the water upon the leaves of Stra-
tiotes aloides. I have myself observed a very similar caterpillar of a
moth upon Ceratophyllum demersum, but I was not successful in
breeding it. Doubtlessly others also exist among the allied genera and
species, but which have hitherto escaped detection. It must strike as
remarkable, that among the Lepidoptera , which apparently, from the
great development of their organs of flight, are destined to dwell in the
air, larvee should be found which select a place of residence of such a
very opposite nature, whereas among the Hymenoptera , which appear
more adapted to dwell in a variety of media, no single instance
should occur of one having been observed, either in its larva or perfect
state, to live in water. It is indeed true that some of their larvae live
in moist places, such as the parasitic larvae of the Ichneumons , but
branchiae have never yet been detected in them.

§ 127.

B. INTERNAL ORGANS OF RESPIRATION.

The internal organs of respiration are the most simple and most
uniform parts found in the insect body ; for they universally present
themselves as ramose tubes originating from the spiracle, the exterior
air tube, or from the root of a brancliia, and thence spread to all
the other organs. Malpighi, who by his dissection of the silk-worm
was the first to obtain a correct insight into the internal structure of
insects, was also the first discoverer of these internal organs ; pre-
viously it was thought that insects did not breathe, an opinion which
was originally propounded by Aristotle, and subsequently generally
received.

As to the structure of these tubes serving for the function of respira-
tion, and which have been called air tubes or tracheae, we shall find

De Geer, vol. i. part iii. PI. XXXVII. f. 5 and 6.

THE INTERNAL ORGANS OF RESPIRATION. 171

that they consist of three distinct layers, which, taking them from the
exterior, appear in the following form : —

The outermost membrane (PL XXII. f. 11.) is transparent, very
smooth, without being perceptibly fibrous, but hard, and generally
colourless. Coloured tracheae, which we now and then observe, for
example, brown in Locusta viridissbna, red in Phasma gigas, or
black, as in the larvae of Dyticus and Hydrophilus, derive their colour
from this exterior skin, whereas both the others, especially the second,
are constantly of a silvery white, and shining. A dark colour facilitates
very much the detection and unravelment of the extremely delicate
tracheae, particularly when they run upon the clear ground of other
organs. But in those cases where the tracheae are not coloured their
investigation is not very difficult when freshly killed individuals are
selected for the purpose, for in them the tracheae are still filled with
air : they then display themselves as silvery white, glittering threads,
which here and there appeardull and transparent, from moisture having
at those parts already penetrated them. In general, the last and most
delicate ends are still filled with air, which, however, is forced out
when the creature has been long immersed in spirits of wine, and it
then becomes difficult to obtain a satisfactory view of their distribution.
The exterior membrane of the tracheae consequently is structureless,
nor is it in very close connexion with the second, but loosely surrounds
it, leaving everywhere a free space between them, which is quickly
perceived upon a microscopic investigation, and thereby readily con-
vinces us of the presence of at least two layers.

The second layer consists of a single, tense, elastic, and very delicate
filament, which twines spirally around the innermost membrane, so
that its windings are everywhere, or at least very generally contiguous.
This thread appears to be simple and round, but which is occasionally
difficult to ascertain from its delicacy, but the microscope displays how
it distributes itself about the circumference of the vessel, and that it
scarcely leaves the smallest space between its successive windings, and
which is filled only by membrane. In some instances, for example, in
Locusta viridissima , and indeed in all insects provided with large
tracheal stems, the filament becomes broader, resembling a band, and
can be distinctly distinguished as such. Sprengel * detected in such
larger tracheae ramose filaments, or perfectly closed rings, which were

* Commeutar. de Pari., &c PI. 11. f. 14.

172

ANATOMY.

separated by broader membranous spaces, these he has figured as
round in Cetonia anrata % : in Lamia lextor he even saw small spots
between the windings, whereby the vessels of this insect appeared
punctate. When an air-vessel sends off a branch the space between
the two successive convolutions then widens, and the branch com-
mences with its own spiral filament (PL XXII. f. 11), whereas that of
the stem continues uninterruptedly; but if a trachea divides into two
equal branches, each begins with its own new spiral filament, and that
of the stem terminates at the point of division. These spiral filaments
of the tracheae may be considered as analogous to the cartilaginous
rings in the windpipe of the superior animals, although these are sepa-
rated from each other, and connected only by their softer parts. But
this fibrous layer of the muscular membrane in the vessels has the
same function, for the contraction of the spiral filament straitens the
tracheae, and thus helps to promote expiration, whilst its succeeding
expansion facilitates the inspiration by opening a larger space in the
vessel for the admission of air. The cartilaginous rings of the wind-
pipes of the superior animals fully accomplish this last purpose, and
they thereby distinguish themselves from the tracheae of insects.

The innermost third membrane, which Lyonnet, Marcel de Serres,
and Straus-Durckheim admit, but Sprengel denies, is, according to the
investigations of the former, a smooth, transparent, delicate, mucous
membrane, and, as it were, a continuation of the exterior epidermis,
with which it also stands in connexion at the orifice of the spiracles.
The spiral filament lies closely adhesive to it, so that upon a rupture
of the vessel its remains hang affixed to the detached spiral thread,
whence Sprengel prefers considering it as a connecting membrane be-
tween the spiral fibres rather than as a distinct layer. But the fact of
this innermost membrane peeling off when caterpillars moult, or pass
from the larva to the pupa state, and that in place of it a new one is
formed beneath, speaks distinctly in favour of its being considered
as a peculiar and a separate one.

This anatomical structure of the air-vessels is found precisely the
same in all the orders, and although their form is subject to many varia-
^ tions, yet their structure but very seldom participates in this difference.
This participation of the structure in the difference of form is main-
tained by Straus and Marcel de Serres to be found in the air bags of the

* Commentar. de Pari. PI. II. f. 19.

THE INTERNAL ORGANS OF RESPIRATION.

173

Lamellicornia, in which, according to these entomotomists, the spiral
filament is deficient, whereas others, particularly Suckow and Sprengel,
assert that they exist, of which we shall speak in detail below.

§ 128.

With respect to the differences of form in the tracheae, according to
Marcel de Serres they may be divided into three main groups, which
that writer thus distinguishes : —

]. Arterial air-vessels. — They originate directly from the
spiracle, and ramify with the most delicate branches from this simple
stem to all the internal organs.

2. Tubular or pulmonary air-vessels. — They do not receive
the air directly, but stand in connexion with the spiracle by means of
the former. They are larger than the arterial air-vessels, their course
is more regular and straight, their diameter broader, and their branches,
on the contrary, smaller.

3. Vesicular air-vessels. — They are of two kinds, either large
bladders, in which the air collects, and whence the branches spring, or
small bladders in the branches themselves, and frequently the terminal
distended ends of the branches ; both forms are never found together.

Upon inspecting first the arterial air-vessels, as those most generally
found, but little that is extraordinary is to be remarked in them ; each
main stem originates from the internal margin of each spiracle with a
broader base, which narrows somewhat after a short course. Here also
is the point of division of the main stem ; next a branch spreads for-
wards and backwards, which passes to the anterior and posterior spiracles
to unite with each main stem originating from them. By means of these
arches all the stems of the trachea? stand in close connexion together.
Between these two communicating tracheae the remaining ramose
branches originate, and each spreads more particularly to those organs
which lie most approximate to it. These branches frequently open
into each other, and form stems running contiguously to the intestinal
canal, the muscles, and the sexual organs, and whence the delicate
branches for these organs originate.

The number of the branches originating from a main stem, with the
exception of the two connecting tubes, is indeed very variable, but wre
may assume that more branches spread from the tracheae of the thorax
than from those of the abdomen. This arises from the greater number
of organs existing in the thorax, particularly the number of muscles.

174

ANATOMY.

whereas in the abdomen there are many spiracles, but proportionally
fewer internal parts. The vessels of the thorax consequently belong
more to the organs of motion, and those of the abdomen to the intes-
tinal canal and the sexual organs.

Two of the many branches which the main stem of the first thoracic
spiracle sends off always go to the head. One runs superficially over
and contiguous to the mandibulary muscles, and also unites to its oppo-
nent upon the opposite side (Melolontha) , and distributes itself with
its branches to all the superior internal portions of the head. From it
the ring encompassing the eye proceeds, or, where this is wanting, the
branches which spread in the pigment of the eye. The inferior branch
accompanies the nervous cord and the oesophagus into the head, and
distributes itself to the lower lying muscles, the maxillae, and the
labium. A third branch, which descends downwards anteriorly, or as
in the Mantodea, two equal branches spreading in this direction pass
into each anterior leg, and each distributes itself with innumerable ra-
mifications to its very point. The extreme posterior branch is the one
connecting it with the second thoracic spiracle, the remainder origin-
ating between this and the beforementioned one, distribute themselves
to the muscles, and several pass into the meso-thorax. The spiracle
between the meso- and meta-thorax, generally the smallest, has also
the fewest branches, namely, besides the connecting ones which unite
it to the first and third spiracle, it has a main branch for the middle
leg, and several ramifications for muscles. From the third spiracle
between the meta-thorax and the abdomen it is generally that the
greatest number of branches originate, namely, the two connecting
branches, the branches for the third pair of legs, and several large
ones to the muscles. The spiracles of the abdomen have each their
two connecting branches, and besides which several ramifications for
the internal organs. The number of these branches differs much in the
genera and families, but they are about the same from the several
spiracles. In the Mantodea they unite to a second, more internal,
common duct, and from which the branches for the internal organs
originate *.

In all caterpillars, maggots, and in the larvae of the Hymenoptera
we observe only arterial vessels, the same in all the predaceous and
swimming beetles, and in the Heteromera and Tetramera . In all other

* Marcel de Serres, M£m. du Museum, vol. iv. PI. XVI. f. 1.

THE INTERNAL ORGANS OF RESPIRATION.

175

insects vve find them in conjunction with pulmonary and vesicular
vessels, but the terminal ramifications, as well as the secondary ones,
are of the arterial description.

§ 129.

Tubular air vessels are chiefly peculiar to such larvae as are provided
either only at one end or at both ends of the body with spiracles ;
besides which the communicating tubes of the stems of the spiracles
are tubular. Under the name of tubular we understand such air-
vessels which proceed uninterruptedly from one end of the body to the
other, and which only send forth here and there small accessory
branches ; or else the simple communicating vessels between two ap-
proximate spiracles, and which are without any accessory ramifications.
Both have this in common, that they preeminently extend according
to the longitudinal axis of the body, whereas the arterial air-vessels
take their course in an opposite direction to this longitudinal course.
Whence it becomes apparent that the tubular air-vessels are never insu-
lated, but can only exist in conjunction with the arterial; the former
are, as it were, the main stems and the latter their twigs.

We will now describe in greater detail some of the chief tubular air-
vessels.

With respect to their first form we may assume that all larvae
which live in water possess more or less developed tubular main
stems. Among the Coleopter a this is the case in the larvae of
Dyticus and Hydrophilus. The yellowish green larvae, figured
by Roesel * of the large water-beetles ( Dyticus marginalis, dimi-
diatus, &c.), have two large spiracles at the apex of the last abdo-
minal segment, exteriorly contiguous to the short, plumose, anal apex.
Two large, broad, black tracheae originate from them, which ascend
undivided as far as the first thoracic segment, the future prothorax.
There each furcates, and then both branches run to the head,
one spreading over the muscle of the mandible and the other beneath
it. Two small accessory branches of these two main stems spring from
it at the commencement of each abdominal segment, but the inner one
of these two is considerably the largest in the fourth, tenth, and
eleventh segments, for these three pass to the intestinal canal, the
anterior one to the stomach, the posterior ones to the ilium and thick

* Insectenbelustigungen, tom. ii. Wasserinsekten der Ersten Klasse, p. 8. PI. 1
f. 2—7.

176

ANATOMY.

gut, whereas all the rest are branches which run off to the muscles.
But, on the contrary, the two exterior branches in the second segment
exceed the inner ones in size, turn upwards to the back of the seg-
ment, and here anastomose, whereby is formed one transverse commu-
nicating passage between the two main stems. All the transverse
accessory branches are here arterial, but the large main canal which
runs longitudinally in the insect is tubular. We find a similar dispo-
sition and structure, in all the essential portions, in the tracheal system
of the larva of Hydrophilus piceus, as is evident from Suckow’s figures*.

Tubular air-vessels are very general among the Orthoptera, where
likewise, as is always the case, they are connected with arterial
branches, or even with vesicular vessels. The tracheal system of Mantis
oratoria described and figured by Marcel de Serres may serve us for an
example f . Two narrow vessels originate from each of the seven
abdominal segments, the shorter exterior ones of which unite in a
direct tubular vessel, which runs beneath the margin of the abdomen,
and passes on to the third spiracle of the thorax. The inner somewhat
longer vessels unite in arches, forming a second longitudinal tube,
which proceeds in an undulating line close to the superior wall of the
intestinal canal, and also passes into the thorax. A third tubular
vessel comes out of the thorax, running very closely to the intestinal
canal : it also takes an undulating course, but beneath that organ, and
sends forth branches laterally, which again unite in a fourth direct
tubular vessel, and which is connected at its anterior and posterior
extremities with the first named one, which runs at the edge of the
abdomen. All these tubular vessels give off but few branches, and it
is only from the central lower longitudinal tube that some delicate
branches are given off to the intestine, and it is from the central inner
small vessel, originating at the spiracle, that the air tubes come for the
sexual organs.

The air-vessels of the larvae of the Libellulce are also tubular, and
are very uniform in their distribution with those of the larvae of the
beetles which live in water. Two large main stems, serpentine at the
dorsal portion of the intestinal canal, which, after being bound by the

* In Heusinger Zeitschr. vol. ii. No. i. PL IV. f. 26. See a detailed description in
H. M. Gaede Dissert. Sistens. Observation, quesd. de Insector. Vcrmuiuque Structura.
Chilon, 1817. 4to.

+ M4m. du Museum, tom. iv. PI. XVI. f. 1.

THE INTERNAL ORGANS OF RESPIRATION.

177

colon, from which they originate in a tuft, take their course to the
head, where they again, furcate. On each side of the ventral portion
two smaller vessels lie, which are united to the dorsal vessels by means
of transverse branches. The upper one of these runs also to the head,
the lower one, taking its course nearly in the centre of the body, termi-
nates on the contrary in delicate ramifications * at the stomach. We
find also in the perfect insect both the ventral and dorsal stems, the
latter communicating by means of delicate canals with the seven spi-
racles of the abdomen.

The tubular vessels, lastly, are found very generally in the larvae of
the Diptera. The larva of the common gnat ( Culex ) has two large
dorsal stems, which originate, already divided, from the above described
posterior air tube, and give off their fine branches to the internal
organs t. In the larva of Eristalis tenax, Meig., which has been called
the rat-tailed maggot, from its long air tube (PI. II. f. 8.), both the
two great tracheal stems unite, previously to their passing into the inner
tube of the air tube, by means of a transverse branch, and remain for
a small space separated, lying convoluted in front of the internal aper-
ture of the tube, but it is only where they pass into the inner tube that
they are truly united together. In the body itself they are never again
united, but in the first segment in the membranous head there is ano-
ther connecting tube which proceeds directly behind the cerebrum. In
front of this connection they become considerably narrower, but behind
it each stem proceeds out of the head as a fine tube passing into a small
air tube placed at each side of the head, which were necessary for the
expiration of the previously inspired air. It is probable that such
anterior air tubes are found also in the larvae of other Diptera. A
similar structure is found in the larvae of all the flies ; but they want
the tail, and both the tracheal stems separately vent themselves at the
posterior obtuse surface of the body (PI. II. f. 1.).

The larvae of the Hymenoptera have also tubular main stems, but
which, as they are formed of small tubes that proceed from the spi-
racles, are never so large and developed. Two main stems consequently
proceed on each side of the body, united in each segment by means of a
transverse connecting vessel, but there orginate from them, at those
places where the tubes of the spiracles pass into them, innumerable

* Suckow in Heusinger, f. 7. & 9.

f Swammerdam Bib. Natur?«, PI. XXXVII. f. 5. h.

178

ANATOMY.

ramose or arterial vessels, so that the tubular main stem is less insu-
lated *. Precisely the same structure is exhibited in the larvae of the
Lepidoptera, but the peculiar tubular structure is still more indistinct,
for in general the transverse connecting tubes are also wanting.

§ 130.

The vesicular air vessels are properly only distended tubes, or the
distended ends of accessory branches, it is thence that they are never
found alone, but they are always in conjunction with arterial or tubular
air vessels. They also appear under two chief forms, for they are either
very large bladders, lying chiefly in the abdomen, whence arterial air
vessels originate, or they are the vesicular distensions of the branches
of arterial air vessels themselves.

The first form of the vesicular air vessels is found in the Hymen-
optera , Diptera , Cicada , and in a somewhat altered figure in many
grasshoppers.

In the Diptera, at least in the true flies ( Muscidce) the Syrphodea
and the CEstridae , two large air bladders have been observed at the base
of the abdomen, contiguous to the intestinal canal, which are tolerably
uniform in structure with the large tubular vessels, but the twistings
of the thickish spiral filament are wider apart, the filament itself
divides here and there, and is interrupted at other parts, whence the
entire surface does not appear so regularly transversely striated as in
the tubular vessels (PI. XXII. f. 12., membrane of the air bladder of
Musca vomitoria). Their form is regulated by that of the abdomen,
so that they are often ovate or very generally vertically compressed,
and are here and there angular, in consequence of constrictions. A
large trachea originates from their under surface ; it runs forward and
backward to the head and anus, and gives off lateral tracheae to the
spiracles of the thorax and abdomen. Other finer vessels run over the
superior surface of the bladder, and ramify to the internal organs.
Whether they originate from the bladder itself or from the connects
ing vessels lying beneath it I could not perceive distinctly in flies, but
it is the case in Scolia and in Apis according to Leon Dufour. But
this whole air bladder is nothing else than the tubular vessel of the
larva, which during the pupa state has shortened and distended, and of
which we took notice in the preceding paragraph ; this air bladder must

Compare Swammerdam Biblia Naturae, PI. XXIV. f. 1. in Apis Mellifica.

THE INTERNAL ORGANS OF RESPIRATION. 179

consequently be found in all flies whose larvae breathed through the tail
itself, or through spiracles seated there. The presence of this air
bladder explains the cause of the glassy perfectly transparent abdomen
of so many Diptera, for example, of Volucella pellucens, Meig. The
Asili, which have a longer, narrower, more extended abdomen, possess,
according to Marcel de Serres *, several small and successive vesicles,
for example, Asilus barbarus has sixty on each side.

Many Hymenoptera display a similar structure. In some species of
Bombus I have found precisely the same air bladders at the commence-
ment of the abdomen, as has also Leon Dufour in Scolia f .

Carus J has described them in the large Cicada. The air bladder
originates within the circumference of the large spiracle which lies
between the thorax and abdomen, it distends a little anteriorly, but
spreads especially backwards, where it extends to the sixth or seventh
segment ; before impregnation, whilst the ovaria and testes are still
filled with their contents, they are limited to a smaller space, but after
copulation they occupy almost the whole abdomen, particularly in the
males, in which they are generally larger in compass, doubtlessly in
connection with the vocal organ, which in the females is merely indi-
cated. Hence is explained the opinion of the ancients, who held that
the males were empty.

In the grasshoppers the bladders have a somewhat different connec-
tion with the rest of the respiratory system ; and they also vary con-
siderably in form from the former, for in these they consist of bags of
a somewhat longish oval shape, very pointed at both ends. In Locusta
viridissima two such bags originate at each spiracle, they thence ascend
close to the inner side of the general integument up to the back,
where they attach themselves to a flat horny arch, which originates
from each ventral plate projecting into the cavity of the abdomen, and
which is affixed to the ventral plate only at its commencement. Each
of these arches supports two air bladders, which, however, do not pro-
ceed from one but from two separate spiracles, so that they altogether
form a zigzag line. But they are connected also above and below by a
narrow longitudinal tube, and from the lower ones there are vessels
connecting them with the opposite ones of the other side, and from the
upper ones originate the branches which are distributed to the internal

* M£m. de Mus., as above, p. 362. f Journal de Physique, Sept. 1830.

+ Analekten zur Naturwissenschaft und Heilkunde. Dresden, 1828. page 158. fig.
15—17, 9.

N 2

180

ANATOMY.

organs. Thus, therefore, the air bladders of the abdomen form a com-
pact net- work, which is, as it were, spread out between the spiracles
and the horny arches. If the abdomen be drawn together by muscular
contraction the horny arches rise, extend the tracheae longitudinally,
and consequently the air contained within them is forced out ; but
upon its expansion the air again streams in, when every bladder,
through the elasticity of its filament, is again shortened and dis-
tended. The respiratory system of Truxalis nasutus, of which
Marcel de Serres has given a figure *, is still more complicated,
for in it the bladders do not originate immediately from the
spiracles, but, by means of long tubes, from the common tubular
vessels which connect all the spiracles, and at the opposite end unite
in a second but more delicate longitudinal tube. Also the two oppo-
site bladders are held in connection together by undivided tolerably
narrow tubes. In the abdomen there are twenty bladders, ten on
each side ; in the thorax six larger ones, four in the meso- and meta-
thorax, one very large pear-shaped one above, at the dorsal portion of
the pro-thorax, close to the crop, and besides many vesicular disten-
sions of the arterial vessels ; in the head there are six large bladders,
two laterally, contiguous to the muscles of the mandibles, two above, at
the vertex over the eyes, two in the forehead before the eyes, and
between these several smaller vesicles.

The second chief form of the vesicular air vessels is found among the
Coleoptera in the family of the Lamellicornia, among the Lepidoptera
in the Crepuscularia, particularly in the males, and then in the
dragon flies.

In the Lamellicornia the chief distribution of the air vessels, as-
throughout the Coleoptera, is arterial, for fascicles of air vessels ori-
ginate from each spiracle ; but each finer branch distends, prior to its
ultimate and finest ramification, into an oval bladder, which is of a
more delicate structure than the rest of the branch, whence Marcel
de Serres and Straus deny the presence of the spiral fibre in these
vessels, which Suckow maintains to be the case. It is true that these
bladders are more transparent than the tubes, but they exhibit a
peculiar punctured structure, as was even perceived and figured by
Swammerdam f , and also by Sprengel J ; and thence I would assume

* As above, PI. XV.

t Biblia Naturae, PI. XXIX. f. 10. J Commentar., PI. I. f. 11 — 13.

THE ORGANS OF GENERATION

181

that in these bladders, as in the larger ones of the flies, the spiral fila-
ment has torn from the distension, and only the rudiments of it are
present in the darker places. These bladders accompany all the intes
tines, pass everywhere between the muscles, and are particularly accu-
mulated superficially beneath the integument. A precise description
is consequently impossible, from the manifold reticulation of the
branches, and a single glance at the masterly representation of it in
Straus will explain it better than any words unaccompanied by figures
could possibly do, we therefore refer to his anatomy of Melolonlha.

The vesicular distensions in the tracheae of the Libellulce are found
chiefly in the thorax, and in it they lie exteriorly, contiguous to and
between the muscles. They are generally pyriform, whereas those of
the Lamellicornici and Lepidoptera are perfectly oval ; the bags also
appear to me to be connected by tracheae and to form distinct lacings.

Among the Lepidoptera we find the bladders chiefly in the male
Sphinges and Vhalence , and are sometimes small and sometimes large,
as in Acheroniia Atropos, Ochs. They are of a coarser structure than
those of the beetles, so that the presence of the spiral fibre is here
subject to no doubt. According to a figure in Sprengel the membrane
of the bladder has sometimes a cellular appearance, and this might then
be considered as an approximation to the structure in the Lamelli-
cornia.

SECOND CHAPTER.

OF THE ORGANS OF GENERATION.

§ 131.

The second chief system of the vegetative organs comprises the
sexual organs destined to the propagation of the species. Under this
name we understand both the vesicular and the tubular parts which lie
in the abdomen generally affixed at one end, which, in a variety of
forms and connections are united together in main stems, and open in
one evacuating duct at the end of the abdomen beneath the anus. This
last definition is subject to no exception in true insects, for what has

* Commcntar., PI. III. fig. 24.

182

ANATOMY.

been considered as exterior sexual organs and sexual apertures at the
base of the abdomen in the male Libellula are by no means such parts,
as we shall have an opportunity of proving below ; in them also that
aperture is found at the end of the abdomen, in the vicinity of the
anus.

These vesicular and tubular organs consist, like the intestinal canal,
of several divisions, which, as the general character and function of the
sexual organs consist in the secretion of fluids, may be distinguished
as proper secreting organs (testes and ovaria), conducting organs for
the secreted fluids (vasa deferentia and ovi ductus), repositories for the
secreted fluids (vesica seminalis and uterus), and as evacuating organs
of the secreted material (ductus ejaculatorius and vagina). These main
divisions are found in function, although frequently but little distin-
guished in form and figure from each other, in all the internal sexual
organs, as will be shown in the course of our investigation. This
sketch consequently comprises the most general structure of these
organs, and it will therefore be merely the individual, generic, family,
and ordinal differences which will occupy us in the course of our inves-
tigation ; but we will previously say something about their anatomical
structure.

§ 132.

The determination of the structural relations of the membranes of the
sexual organs is subject to many difficulties, in consequence of the
delicacy and minuteness of these parts. It is only in those divisions
which possess a greater extension that it has been possible to distin-
guish the presence of two layers of membrane. The exterior of these
two membranes is coarser, firmer, and of a muscular consistency ; the
internal one, on the contrary, is more delicate, transparent, simple, and
corresponds with the internal mucous tunic of the intestinal canal or
the exterior epidermis. The presence of both the membranes in the
large vesicles is subject to no doubt ; they can there be readily and
securely exhibited ; even in the more delicate evacuating ducts of the
secerning organs they are distinguished by the difference of their con-
sistence, which in the internal one is considerably less than in the
external one. It is more difficult to prove their presence in the secerning
organs themselves, but J. Muller * has shown them, at least in the

* Nova Acta Phys. Mod. XII. 2. PL LY.

THE ORGANS OF GENERATION.

183

ovaries: but it still remains doubtful whether the glandular testes
consist of these two layers, which, however, may be assumed, from
the similar structure of analogous parts.

§ 133.

The preceding observations apply with equal force to all sexual
organs. But if we contemplate their general form we shall imme-
diately meet with varieties which do not admit of any further generali-
sation, and this circumstance compels us in this place to examine more
closely the differences of form which the sexual organs severally
present.

Propagation is, like life in general, the result of two agents acting
reciprocally upon each other. In the lowest forms of organisation,
where such a separation of the animating activities shows itself less
perceptibly, the propagating agents themselves cannot either appear
separately, we consequently there find simple germs susceptible of
development. By degrees an active and a passive agent are pro-
duced, both of which are found at first in the same individual (snails),
but they soon separate into two distinct individuals, and thereby
constitute the essential character of such individuals. In the former,
luxuriant energy, universal momentum, and a continual impulse
towards the appeasement of internal urgent desires ; in the latter,
patient sufferance, quiet reserve, a tarrying for excitement, and an
ultimate satisfaction in the discovery, of the deficient unknown some-
thing. The former character is called the male, and the latter the
female. But where shall we find the differences of these two
characters more distinctly expressed than in the multiform insect world ?
The above cited distinction is here found so strongly marked ’that its
high significance can no longer be subjected to doubt. We shall return
to this subject in our physiological chapter, and it is there only that
it will find its true place ; we can merely indicate it here to enable us
to arrive at the primary difference of the sexual organs. This we have
now found, we have thus become acquainted with two kinds, and have
distinguished them as male and female.

§ 134.

The differences of the organs of generation of both therefore lie based
deeply in the conditions of life. We necessarily ask, how does it become
evident to us ? Anatomically investigated, the character of the female
is the formation of the germs, that of the male secretion of sperm ;

184

ANATOMY.

all organs, therefore, which display germs (eggs) are female, and all
which prepare spermatic moisture must be called male. The female
sexual organs of insects consequently display bags full of eggs, ovaria ;
the male, sperm-secreting vessels or glands ; from both originate the
above characterised closer or more distant evacuating ducts, which are
pretty uniform in both sexes. We may consequently distinguish in
both female and male organs different divisions, which are, however,
connected together, and which must necessarily constitute the different
divisions of our description of the sexual organs.

§ 135.

I. Of the Female Organs of Generation.

The female sexual organs {genitalia feminina ) of insects consist of
internal and external ones ; the internal ones of ovaries, the oviduct,
the uterus, other peculiar appendages, and the vagina ; the exterior
ones of the orifice of the vagina, and its appendages, as the
ACULEUS, the VAGINA TUBIFORMIS, and the VAGINA BtVALVIS.

It is not always that all the above named parts are present together,
either one or several are wanting, the ovaries are deficient only in
barren, undeveloped females (the neuter bees, &c.), but the evacuating
ducts never ; all other appendages may, on the contrary, disappear.

A. Internal Sexual Organs,

§ 136.

THE OVARIES.

The ovaries are tubes or bags in which the eggs are secreted from
the formative substance of the creature, and where they remain until
their impregnation. We always find in insects two such organs of
similar structure in the same individual ; they are so placed that one
lies on each side of the intestinal canal, generally filling the lateral
space in the abdomen. In colour they are generally yellow, but in
form they are subject to many varieties, which, however, may be classed
under the following divisions

I. The ovaries are simple bags, in which the germs of the eggs ar
contained. This primary form, which is the most simple of all, is
subjected to no subordinate differences *.

* The ovarium saccatum described by J. Miiller in Nova Acta Phys. Med., tom. xii.
p. 612. does not belong here, but will be classed below, with the ovarium furcatum.

FEMALE ORGANS OF GENERATION.

185

Such ovaries are found in Ephemera and Stratiomys. Midler
calls this form bunches of ovaries ( ovaria racemosa *), and supposes
that the exterior- tunic of the bag, or properly the bag itself, is
wanting, the eggs being connected together by means of air-vessels ;
but Swammerdam’s figure misled him -f. In a female of Ephemera
marginata, Fab., De Geer, which I dissected, 1 clearly observed the
exterior tunic, the ova were contained within it, egg being linked to
egg by a delicate filament. In Stratiomys also Swammerdam has dis-
tinctly represented the bag

II. The short ovaries, which contain but few germs, are placed
longitudinally upon a large, bag-shaped, common ovarium.

There are many subordinate differences of this peculiar 'form, which
we will briefly indicate.

1. Ovaria pectinata (PI. XXVII. f. 2.) are short egg tubes,
which contain but few germs, and are placed in a row upon the upper
side of a common duct ( Mantodea ).

2. Ovaria echinata, common egg ducts, long, broad, wider ante-
riorly and suddenly pointed, having beneath many very small scale-
shaped egg tubes, which lie over each other (dragon flies).

3. Ovaria imbricata (PI. XXVII. f. 8.). The whole upper sur-
face, with the exception of a narrow edge upon the lower margin, is
covered with short tile-shaped egg- tubes, which lie upon each other,
and embrace the intestine like a roof. Each tube contains a large
developed egg and behind it the minute germs of two or three others
(grasshoppers, crickets, Pliryganea , Sialis, Tipula, Sirex, & c.).

4. Ovaria baccata. The common ovarium is a bladder or tube
upon the entire upper surface of which are placed the short egg-tubes,
generally containing but few eggs, {Coleopter a vesicifiea, each tube
with from one to four eggs ; Semhlis , each with six to nine eggs).

5. Ovaria dichotoma (PI. XXVII. f. 5. ovaria fur cata, Müller).
The common ovarium is forked, and upon each prong, and particularly
upon their opposite sides, there are many tubes, containing but few (3)
egg germs ( Gryllotalpa ).

6. Ovaria ramosa (PI. XXVII. f. 6.). The common egg duct
does not simply furcate, but several branches are given off one after
the other, each of which contains some egg germs ( Lepisma ).

* Nova Acta Phys. Med. p. 601. 11. + Bib. Natur«, PI. XXV. f. 1,

f Ib.Pl. -XL VIII. f. 1.

186

ANATOMY.

III. Long tubular ovaries, which contain many egg germs, are col-
lected together at one part of the common duct. These tubes are either
entirely free, and distinctly separated from each other throughout their
whole course, or else united together by a loose cellular tissue (for ex-
ample, in Harpalus ruficornis).

1. Ovarium spirale (PI. XXVII. f. 10). There is but one egg-
tube to each ovarium, but which is very long, and it is twisted spirally
from its apex to its base ; a rare form, which has been observed only in
Sarcophaga carnaria and some other kinds of flies.

2. Ovaria furcata (PI. XXVII. f, 7* Ovaria saccata, Müll.).
There are but two short ovaria, containing indistinct egg germs, and
which unite with the common duct by means of a fork ; at the point
of union there is a bag (uterus) in which the egg germs pass through
their changes until the pupa state ( Diptera pupipara *). In Polistes
also there are but two egg-tubes, each of which however contains
several eggs.

3. Ovaria digitata (Pi. XXVII. f. 8 and 9). A few, from
three to five, such egg-tubes hang at one spot of the common duct.
Many Lepidoptera (for example, Liparis Mori , with four tubes, each
of which contains about sixty eggs), particularly the smaller ones (for
example, Tinea, likewise with four tubes, each of which contains
about twenty-five eggs; and Ptcrophorus, with three tubes, each
containing about twelve eggs) ; and the Hymenoptera , (for example,
Chrysis, with three tubes, each with three eggs ; the same in Xylo-
copa ; in Anthidium, also three tubes, each with about eight eggs).
In Nepa, Pediculus, and Psocus there are five tubes, each in the
latter genera containing five eggs.

4. Ovaria verticillata (PI. XXVII. f. 11). Many very long
tubes originate at one spot, upon the very short common egg duct.
They run upwards in a long filiform point.

Such ovaria are found in the majority of female insects, namely, in
most Lepidoptera, many Hymenoptera, and almost all Coleoptera.
Midler’s ovaria conjuncta are but a trifling variety of this form, the
superior filament hanging more closely together, and forming an inter-
twisted cord. The fertility of the species regulates the number of the
egg-tubes and their turgidity. Orycles nasicornis, Melolontha , Cctonia,

* Leon Dufour in the Annales des Scienc. Nat. tom. vi. p. 299, &c. According to him
the ovaria contain merely a whitish mass, but no distinct egg germs.

FEMALE ORGANS OF GENERATION.

187

and Notonecta have six tubes, each with from five to six eggs ; Vespa
vulgaris and Silpha atrata seven tubes ; Tenebrio, Leptura, Saperda,
Blatt a, Ascalaphus, Bombus terrestris, from seven to ten tubes, each
with from four to six eggs ; Cicindela, Carabus, Dyticus, Staphylinus,
Hydrophilus, Cerambyx , Lamia tristis from ten to fifteen tubes ; Bu -
prestis mariana twenty ; Blaps mortisaga thirty, each with four eggs ;
Apis mellifica above a hundred, each with seventeen eggs.

5. Ovaria capitata (PL XXVII. f. 12). They merely differ from
the preceding in their short tubes not running upwards in a point, but
which distend into a large knob, whence the point proceeds as a thin
filament ( Lucanus ).

§ 137-

The situation of these very various ovaria is nearly the same in all
insects, for they always lie laterally in the abdomen contiguous to the
intestinal canal, and fill the whole remaining space of the abdominal
cavity not occupied by that organ. They often lie free and separated
from each other, but sometimes fold over from both sides towards each
other, and thus form a covering over the nutrimental canal, containing
it between them. The latter then forces itself into the anterior portion
of the thus formed longitudinal canal, runs within it, and posteriorly
it again presents itself, passing over the common duct, which the colon
always covers above. Such approximate ovaria are connected by the
tracheae, which approach them with their large stems, and then accom-
pany each of their individual tubes by delicate accessory branches to
their very extremity. There is still another means for retaining the
ovaria in their place, which is their communicating duct with the
dorsal vessel, discovered and described by Joh. Müller*. Each indi-
vidual egg-tube, or occasionally the common egg bag, extends in a thin,
very delicate, but tolerably firm filament, which ascends anteriorly and
above to the dorsal vessel to discharge itself therein. This connexion
invariably takes place at that portion of the organ which we have
described as the aorta, sometimes at a great distance from the ovarium,
for example, in the thorax. This kind of connexion is peculiar to the
ovaries of the third chief division, for the connecting filaments of each
egg-tube unite in a cord, or frequently, prior to their connexion with
the dorsal vessel, they meet and form a single short tube, for example.

Nova Acta Phys. Med. n. c. vol. xii. part ii. page 555, &c.

188

ANATOMY.

in Cardbus*. The connecting filaments of the egg-tubes of the second
class remain, at least frequently, separated, and discharge themselves
singly into the aorta f. It yet remains undiscovered how the connexion
is formed with the vesicular ovaries, but it is probable that a single
duct passes from the end of the bag to the artery.

We shall treat of the use of this connecting duct, which Müller has
so admirably represented, in our physiological division, where we speak
of the development of the eggs.

§. 138.

THE OVIDUCT.

The oviductus, or tuba ovarii , is that portion of the evacuating duct
of eggs which extends from the ovarium to the connexion of the two ova-
ries in the common evacuating duct. It is a delicate long or short tube,
sometimes thin and filiform, or broader and vesicular, and when so it has
a thicker muscular structure ( Semblis ). It is rarely that each oviduct
is supplied with peculiar glandular appendages which secrete a gluten
to spread over the eggs, by means of which they are glued together.
In Hydrophilus , which has four such appendages attached to each side
of the oviduct, they are filamentary, gradually decreasing, blind canals,
and have a granulated glandular appearance, and are doubtlessly
glands, and most probably secrete the material from which the female
prepares the glutinous mass enclosing the eggs ; but where such ap-
pendages are wanting this takes place in the vagina, or in the duct com-
mon to both ovaries, which is then supplied with peculiar appendages
for this purpose.

In general the oviduct is longer in small ovaries which contain but
few egg germs, shorter, on the contrary, in larger ones rich in germs ;
but their dimensions are regulated by the age of the insect ; long ducts
are found in young individuals, and they become shorter in older ones
which are ready for impregnation, or already impregnated.

§ 139.

That portion of the duct of the ovaries which extends from the
union of the tubes to the orifice of the spermatheca is called the egg-
canal. It is generally of greater compass than the oviduct, and
distends into a belly in the middle, forming a convenient cavity for
the reception of the eggs. But no other object attends this reception

* Nova Acta Phys. Med. n. c. PI. LI. f. 3. f Ib- P1- L- f- 2<

FEMALE ORGANS OF GENERATION. 18$

than their mere passage, for the impregnation of the egg, as we shall
see below (§ 208), does not take place here, but probably at the end
of the egg-tube, at least its development commences there. In those
instances only in which this portion of the female organs is provided
with appendages which secrete a gluten do the eggs remain somewhat
longer in this common duct to be covered by the secretion of those
glands, that they may be thereby fixed as with a gum to the leaves of
plants and other objects. Consequently this portion of the sexual
organ is nothing more than a canal, and we must ascribe as well
to insects as to many other inferior animals a uterus bicornis ;
indeed in the majority of cases, particularly those which possess ovaries
having many egg-tubes, a uterus multicornis, for at the end of the egg-
tube the development of the egg commences, and here consequently also
its impregnation by the semen ensues.

§ 140.

APPENDAGES TO THE EGG-CANAL.

The egg-duct is most rarely a simple organ unprovided with vesicular
or vascular auxiliary cavities, as, for example, in Donacia, Eristalis
tenax, Musca, Tipula, Ephemera (PI. XXVII. f. 13) ; in the majority
of insects, on the contrary, it exhibits various appendages which take a
variety of forms, and exercise different functions.

These appendages vary in number from one to five. If one only be
present it is always a vesicular or purse-shaped distension of the duct,
which appears destined to the reception of the male semen during copu-
lation, and is thence called the spermatheca. This organ is always
situated at the superior parietes of the duct, and opens into it with a
small orifice surrounded by a callous margin. This margin is properly
the sphincter of the neck of the bag, which prevents the escape of the
semen. When it opens the semen flows immediately into the duct
from the mere situation of the bag. According to Audouin, the male
organ during copulation passes into the orifice of this bag, and thus
pours the semen directly into this receptacle. We find this kind of
simple vesicular appendage in Acheta, Blatta, Anthidium (PI. XXVII.
f. 14.), Ascalaphus , Sialis , Semhlis , Psocus, and Nepa ; the same in
Hydrophilus, Tenebrio, Lytta, and Chrysis, but in the latter it has a
superior or lateral vascular apex (PI. XXVII. f. 15.), which is evi-
dently the organ we shall presently describe as the gluten gland. In
general, namely, this vessel discharges itself into the duct contiguously

190

ANATOMY.

to the spermatheca, yet in the instances named above not, but into the
spermatheca itself. It is somewhat similar in Psocns , for here the
gluten vessel does not merely discharge itself into the spermatheca, but
lies entirely in it. For thus I interpret the purse-shaped appendage
found by Nitzsch * in Ps. pulsatorius, in which from one to four pedi-
culated knobs are enclosed which unite into one duct, which runs into
the excretory duct of the spermatheca.

If two appendages are found at the duct it must be carefully
observed whether they are symmetrical in situation and form or not.
Two dissimilar appendages are found in most insects, (namely, the
genera Carabus , Harpalus, Melolontha, Lucanus, Meloe, Spondyla,
Sirex, Apis, Xylocopa, Tinea, Pterophorus, and Cercopis). The one
is larger and broader than the other, purse-shaped, and corresponds
both in situation and function with the just described spermatheca.
In Melolontha (PI. XXVII. f. 16. a ), Lucanus, Spondyla, and Cer-
copis it is a short-necked pear-shaped bladder ; in Pterophorus the
same, but a short blind bag springs from it laterally ; in Xylocopa (PI.
XXVII. f. 17- a). Apis, and Tinea it has a longer very narrow neck;
in Trichius a superior vascular appendage; in Sirex (PI. XXVII. f.
18. a), in which it is very large, at the part where the bladder con-
tracts into a neck, two tolerably long, pointed appendages are found ;
in Meloe it is constricted near the middle, and the lower smaller half
has a round auxiliary bladder, which discharges itself into it by a nar-
row canal.

The second appendage (PI. XXVII. f. 16 — 18. b.) is in general
much longer, but also thinner and vascular. This form itself, which
is common to all the secreting organs of insects, bespeaks its glandular
function. Observation has also taught us that a white glutinous liquid
is secreted in this organ, which, after the eggs are laid, disappears.
This gluten likewise covers the impregnated eggS, and it is very pro-
bably what fastens them together, as well as to other objects ; conse-
quently all appendages which are not spermathecse are called gluten
glands or vessels. With respect to their form, besides the simple,
tubular, and vascular form which are found in Trichius , Tinea, and
Cercopis, there is a clavate one found in Melolontha, and a vesi-
cular one furnished with a short neck in Meloe . In Xylocopa it is a
long gradually decreasing bag, which discharges itself by a very

Compare Germar’s Magaz. vol. iv. p. 281. PI. II. f. 3. e. f. fig. 4 and 5.

FEMALE ORGANS OF GENERATION.

191

narrow tubular pedicle into the uterus ; in Harpalus and Spondyla, on
the contrary, it is a round bladder, which has a very long, twisted, fine
duct, and which in Spondyla contains a hard horny interior ; in Ptero-
phorus the vessel distends before its orifice into an ovate bladder ; and
in Lucanus (PI. XXVIII. f. 1. b, b) there are two such bladders,
which unite by means of two short ducts into a common one, and
originate from very fine, short, twisted vessels, by their distension.
The form of these organs, lastly, is very peculiar in Elater murinus, in
which, according to Leon Dufour, they are vessels successively furcat-
ing, which at the base of each fork distend into a triangular bag. The
symmetrical appendages in Hippobosca resemble these, but the bag-
shaped distensions are wanting.

Where the duct has two symmetrical appendages, as in Lepisma
(PI. XXVIII. f. 3.), Musca, and Pediculus they are always gluten
depositories ; in Lepisma they are large and bag-shaped, and upon
the upper surface here and there constricted ; in Musca longer and
clavate ; but in Pediculus, on the contrary, they are two short blind
bags, provided with accessory points.

We find three appendages in Gryllotalpa, Calosoma, and Stra-
tiomys. In the first instances two of them are equal, namely,
clavate or vesicular gluten vessels, which empty themselves into the
duct by means of narrow canals ; the third, on the contrary, is the
bag-shaped spermatheca, which in Gryllotalpa has another superior,
long, vascular appendage. In Stratiomys Swammerdamm * found
three long, vascular, gluten ducts, which originated from round gland-
ular bodies.

Four appendages are seen in some Lepidoptera , for example, Pontia
Brassicce. The most anterior one is a simple, tolerably long, twisted
vessel, which in others ( Gastrophaga Pini, see further below) consists of
two furcate branches ; the second is the spermatheca ; the following are
again long twisted vessels, which unite in a short duct after they have
previously distended in two oval bladders. In Cicada, Latr. ( Tetti -
gonia, Fab.), in which there are also four appendages, two symmetrical
vessels are found in front of the spermatheca, but the vessel behind it
is simple but much longer than the two first.

Five appendages, lastly, are found in several, particularly the Nociuce.
A bladder-shaped, one-sided, sometimes long and clavate, or distended

* Bib. Naturae, PI. XLII. f. 8.

192

ANATOMY.

and egg or pear-shaped one, which discharges itself into the duct by a
narrow canal, is the spermatheca; the other four are vascular gluten
glands. In Vanessa Urticce they are short, the anterior one broader
than the posterior, both discharge themselves into the duct at one part
but at opposite sides, before the spermatheca ; in Gastrophagd Pint
(PI. XXVIII. f. 4.) they are very long, and the anterior as well as the
posterior unite into a simple but very short canal. The anterior one,
which discharges itself close in front of the spermatheca, is distended
in the middle into a bladder ; in the posterior ones, which discharge
themselves into the vagina, this vesicular distension takes place at the
end of each single tube before they unite into a common duct.

The poison vessels of the Hymenoptera aculeata are appendages of a
peculiar description. In them a round, perfectly ovate bladder (PI.
XXVIII. f. 5, 6. b , b ), with a narrow duct, discharges itself into the
sting, which we shall describe below (§ 145). This bladder lies quite
at the end of the abdomen close to the orifice of the sexual organs. It
contains a bright clear fluid which is secreted by two either long very
fine, much twisted vessels, or of shorter ones, originating from a fasci-
culus of furcate vessels ( Pompilus *), which opposite the orifice sink
into the bladder, and either separated as far as their orifice, as in
Vespa crebro (PI. XXVIII. f. 6. a, a), or as in Apis mellifica (f. 5.
a, a), are united into one vessel, a little distance before the connexion
with the bladder. May not the posterior vessels of the Lepidoptera ,
Which we have just described, be analogous to these, and both be pro*
perly considered as organs secreting urine ?

§ 141.

THE VAGINA.

The last portion of the common evacuating duct lying behind the
fegg-evacuating duct is called the vagina. It is a short direct tube,
narrower than the egg canal but wider than the oviduct. Its function
being to receive the penis of the male and to assist in depositing the
eggs, it is, like all the other organs of insects which require constant
distension, held in this state by horny leaves and ridges. There are
generally three such horny plates, one above, one lateral, and one be-
neath. In Harpalus the superior plate is a thin bone, which towards
the exterior distends in the shape of a shovel, and is there armed with

* Ramdohr, Verdauungsorgane, PL XIV. f. 5.

FEMALE ORGANS OF GENERATION.

193

strong thorns ; in the capricorn beetles ( Cerambycina ) it is elongated
into a horny, many-jointed ovipositor. In Hydrophilus it runs out
on each side into a horny point, which Suckow* considers as the
analogue of the clitoris. In Melolontha the vagina has on each side a
small pocket, into which the lateral wings of the penis pass during co-
pulation, which explains the cause of the protracted union of this insect.

In all insects provided with an aculeus or an ovipositor, the vagina
opens at its base, so that its canal passes directly into that of the ovi-
positor. The valves and spines of this apparatus are consequently
nothing more than the horny bone which lies within the vagina, and
which is then prolonged beyond it.

B. External Sexual Organs.

§ 142.

The external sexual organs of insects do not always project beyond
the apex of the abdomen, but usually lie in the cavity into which the
orifice of the anus and of the vagina open. This cavity, common to
both, is formed of two valves, the one larger, lying upon the dorsal side,
and the other smaller, upon the ventral side, and beyond which the
former projects all round. These two valves, which are not visible
exteriorly, but are enclosed by the dorsal and ventral plates of the last
abdominal segment, are evidently nothing but the last segment itself,
those called the last being the last but one. It is only thus that we can
explain the disappearance of the segments of the larva in the perfect in-
sect, in which we shall also generally discover nine segmentsif we include
the last concealed one. But where there are nine visible segments
the last is not then concealed, but free. It is within this last abdominal
segment, whether it be concealed or free, that the orifice of the vagina is
found, and indeed, beneath the anus, divided from it only by a projecting
plate. The entrance itself is opened, mostly by horny substances, which
have partly been described in the preceding paragraph in the description
of the vagina. The lateral horny ridges, namely, become more elongate,
so that they project as far as the limits of the valves, gradually
separating, and thus forming a spacious entrance. The length of the
vagina depends upon that of these horny ridges ; they are short in the
Carabodea, and often armed at their apex with a strong hook (Har-

* Reusing. Zeitschr. vol. ii. p. 254.

194

ANATOMY.

palus ruficornis), which doubtlessly retains the penis during copulation.
In the capricorn beetles unprovided with an ovipositor (the Prionodea )
they are long, superiorly broader, pointed towards the apex, and gently
bending from each other. There are other forms in other insects. In
the orders possessing an ovipositor they appear as its valves, or as its
wings in those which possess only a vagina bivalvis, this leads us to the
investigation of the free sexual organs which project beyond the apex
of the abdomen.

§ 143.

The free, exteriorly visible, sexual organs of female insects are of a
threefold description, at least three chief forms entomologists have dis-
tinguished by peculiar names, namely, the laying tube ( vagina tubi-
formis), the laying sheath ( vagina bivalvis ), and the aculeus,
called also the terebra, but which is one and the same organ with the
preceding.

The laying tube ( vagina tubiformis , PI. XXIV. f. 14.) is a mere
continuation of the abdomen, and consists, like it, of rings which gra-
dually decrease in compass, so that the largest and first, exactly as is
the case in the telescope, receives within it all the rest, when this organ
is withdrawn within the abdomen, wherein it lies concealed. These
rings are nothing else than segments of the abdomen itself, which have
adopted this altered shape and function in the course of the progressive
alteration of the relations of organisation. The proof that this opinion
is correct is shown in their number, for in the majority of cases (for
example, in the flies,) there are nine abdominal segments, when these
rings of the vagina are added to the visible ones of the abdomen. The
anal aperture also lies in this tube, which could not be the case if it
were merely an ovipositor. Thence, therefore, the last of these tubes
only can interest us here, from its containing the female organs. In
Cerambyx it is a leathery canal, of which that side nearest the venter
is supported by two horny ridges ; at the end of each bone there is a
short two-jointed process, the first joint of which is large, thick, bulb-
ous, and armed on the exterior with short spines ; the second, however,
is small and round, and has two stiff setae at its extremity. In the
flies, which all possess a tubiform vagina, its last joint has above a
horny plate, to which also two short single-jointed, hook-shaped,
crooked processes hang attached. The tubiform vagina of the ruby
tails ( Chrysis ) appears, as far as I have been able to ascertain from

FEMALE ORGANS OF GENERATION.

195

dry specimens, to have precisely the same structure, only that in these,
as well as in the flies, each ring has its horny covering, which are con-
nected together by membranous parts.

§ 144.

The vagina bivalvts is most closely related to the vagina tubi-
formis. It is found in the Orthoptera, some Neuroptera ( Raphidia ),
and the Tipularia. In its most complete development it is a sabre-
shaped tube, which curves upwards, into which the vagina opens, and
it is formed of two valves ( Locusta , PI. XXIV. f. 10 — 14.) I consider
these two valves as the two lateral horny leaves mentioned above in the
description of the orifice of the vagina, and which here are prolonged
and now take the form of valves to that organ. The internal valves
corresponding with the last abdominal segment become also visible, and
here appear as the cover both above and below (f. 10. a, b,) at the base
of the vagina bivalvis itself. All Orthoptera, consequently, have nine
distinctly visible abdominal segments. In Locusta this vagina is long,
sometimes indeed {Locus, viridissima) even longer than the body, each
valve is gently sloped, and has a channel upon its exterior surface which
projects internally as an elevated ridge. At the base it is covered
beneath by the last deeply emarginate ventral segment, above it lies
the anus, and contiguous to it two short, simple, spinous processes.
Between the two larger valves there are two smaller ones (f. 12 and 14.
b, b ,) which are connected by a delicate membrane with the internal
elevated ridge, and sometimes lose themselves in this or remain sepa-
rated from it. Frequently the apex of the exterior vagina is split at
the channel, when the exterior sheath appears, at least at its end, to
consist of four pieces *. In Gryllus, instead of this projecting vagina
we observe four short thick processes, the lower ones of which are
moveable, and form one articulation with the superior ones that are
closely attached to the abdominal cover. From the superior, stronger,
thicker ones thus intimately connected two processes are continued
within the abdomen, and to which are attached the muscles moving
the lower ones ; the orifice of the vagina lies between the lower ones,
and the anus above the superior ones. We may make the following

* Kirby and Spence, Introd. to Ent., vol. iv. p. 152., mention six pieces, but I have
never observed in our indigenous Locusts any but the structure described above, and never
six divided pieces.

o 2

196

ANATOMY.

comparison between this organ and that of Locusta, the lower moveable
processes are analogous to the two valves of the vagina bivalvis, the
superior ones however to the spinous processes contiguous to the anus,
but with this difference, that in Locusta these processes are articulated
to the horny piece which bears them, and which lies between the
orifice of the vagina and the anus ; in Gryllus, on the contrary, the
superior processes form an integral portion of that horny piece. Acheta
agrees in structure with Locusta, but its vagina is more delicately
constructed ; the anal processes are longer, and at their apex apparently
jointed.

The female Tipula have likewise a bivalve vagina which very much
agrees in structure with that of Gryllus. In Ctenophora atrata, two
pointed, long, and sabre-shaped processes originate above from the last
dorsal plate, and bend from the sides towards each other, forming a
bivalved vagina. They correspond to the superior immoveable processes
of Gryllus or the moveable processes of Locusta. Beneath this last
dorsal plate, and consequently between the valves, the anus is placed.
A triangular fleshy process encompassed by a delicate horny margin
separates it from the orifice of the vagina lying beneath it. It also
has on each side two processes of the last ventral plate, which are
above shorter, broader, inwardly arcuate, and gently bowed externally.
These two valves form the true vagina, and therefore correspond to the
inferior processes in Gryllus and the long vaginal valves in Locusta .
In a state of repose they lie concealed between the superior or anal
processes, and all four appear to form a bodkin-shaped process.

§ 145.

The terebra, or aculeus, is found in all the Hymenopiera and
in the Cicadaria.

With respect to the aculeus of the Hymenoptera, although it has
been occasionally tolerably well explained by the earliest entomologists,
it has not always been recognised by modern ones, and therefore fre-
quently imperfectly described. This fact is the more striking as it
has actually nearly the same structure in its essential parts in all the
families, and is merely subject to slight differences of form. For the
present we will pass these over, and proceed to examine its essential parts.

The chief character in which the terebra is distinguished from the
vagina bivalvis is the presence of a second pointed boring organ lying
between the valves. This fuller development of it is not found in the

FEMALE ORGANS OF GENERATION.

197

vagina bivalvis, but it is indicated in the shorter internal valves, which
in Locust a viridissima are united to the larger ones by membrane, but
in other instances they are found free and separate. The terebra
of the Tenthredos is an intermediate form ; it, consequently, does
not pierce firm substances, but merely guides the eggs into already
existing cavities ; but the aculeus forms the cavity itself for the egg,
pierces into bodies not firmer than itself, and as a defensive instrument
it wounds very severely. We may therefore distinguish the exterior
sheath ( vagina aculei ) and the inner sti^g ( nculeus , seu terebra ) as
the chief parts of this kind of ovipositor ; we will first turn our atten-
tion to the sheath.

We have but little to say of the exterior sheath, for its differences
are unimportant. It always consists of two valves (PL XXIII. f. 6.
a, a), which are united by articulation with the dorsal plate of the last
abdominal segment, by which it is partially covered above ; the ventral
plate then covers it from below. They are as long as the sting itself,
and lying together form a tube, in which the latter is completely con-
cealed. If the sting project beyond the apex of the abdomen they
accompany it. A thus projecting sting ( aculeus exserlus ) Latreille
calls a terebra. But when the sting lies concealed within the abdomen
(as for example, in the bees,) the valves are there also, and they embrace
the concealed sting ( aculeus absconditus ) precisely in the same way
as the exserted one. The exterior upper surface of the sheath is
generally rough and uneven, particularly in the projecting aculeus,
and entirely covered with short hair; the edges are simple, smooth,
and fit closely together.

The internal sting is differently formed according to the peculiarity
of its function.

In the Tenthredonodea it diverges most in form. In these it should
not properly be called a sting, but a saw, and indeed earlier entomologists
have compared it with this tool. It consists (PI. XXIV. f. 8.), like
the sheath, of two valves {a} a, and b, &), between which at their base
there lies a short triangular process (c). Each internal valve has the
same form as the sheath enclosing it, but it is smaller, so that it can be
entirely embraced by it. The inferior edge of the inner valve is finely
toothed (PI. XXIV. f. 9. «), very sharp and narrow, inwardly sepa-
rated by a projecting line from the remaining very smooth surface of
the valve. The exterior has likewise a corresponding projecting ridge
(the same, b, b)} which, like the ridge, is finely and sharply toothed ;

198

ANATOMY.

raised lines run over the whole of this surface from tooth to tooth,
and from the elevated ridge to the superior edge, which makes the
whole exterior surface even, and gives it the appearance of a fine file.
With this saw-like apparatus the Tenthredo cuts the substance of
leaves, letting an egg drop in, which is there developed that it may
subsequently feed upon it. The short triangular process forms
merely a key-stone to the margins, gaping at the base, and is of no
importance to the function of the organ ; but it is necessary to men-
tion it, as it is of great consequence in the structure of the sting in the
rest of the Hymenoptera.

If we examine the projecting sting of the Ichneumons, for example,
Pimpla (PI. XXIII. f. 12 — 14.), we first observe the two exterior
valves, (f. 14. a, a ,) and between them, a fine horny sting which is a
little dilated at its extremity (f. 12.). This sting was long considered
simple, and even Gravenhorst, in his monograph of the European Ich-
neumons, describes it so *. But it also is double ; the upper part
(f. 13. a. and 12. a.) is channelled beneath, completely smooth, and
only at its broader point beset with small teeth ; the lower (the same,
b,) much finer portion is a hair-shaped very pointed bristle, which lies
within the channel of the superior one ; this also is broader in front and
lancet-shaped, and fits into a cavity of the upper part of its own shape.
There is thus truly a passage in the aculeus, but so narrow an one that
no egg can pass down it, and in this cavity how should it move along ?
The egg merely slides down the superior channel, and is secured and
pushed on by the inferior bristle pressing against the channel from the
base towards the apex, pushing the egg above it. But, to refer this
structure back to that described in the saw-flies, we must conceive the
two internal valves as united in the superior simple half tube, and
the bristle as the elongation of the central process at the base of the
valves.

Its structure is still more artificial in Sirex and the Bees. In Sir ex
(PI. XXIII. fig. 5— — 11), in which the sting projects, we find likewise
the exterior valves ( a , a) and the central aculeus ( b ). This again
consists of the superior channel (c, c,) and the bristle lying within it,
which is here double. ( d.d .) All three are dilated at their end (f. 7), the
channel is split, and that portion as well as the bristle upon its entire

* Ichneumonologia Europaea, tom. i. p. 89. “ Hsec seta terebra est, et canali centrali
longitudinali instructa esse dicitur, per quern ova poneruntur.”

FEMALE ORGANS OF GENERATION.

199

margin beset with short serrated teeth (f. 9 and 10). That the bee’s
sting is similarly formed, although it lies in the abdomen, is shown in
Swammerdamm’s figure*. Latreille cites the true aculeus in Sirex
as doublet, but personal investigation will readily convince of his
error and the correctness of our representation. The spirally twisted
aculeus of Cynips (PI. XXIII. f. 15 — 18), according to the opinion of
early entomologists, viz. of Roesel, differs in structure from that of the
bee’s only in that its apex, which is covered by valves beset with hair,
projects above the abdomen. Its supposed spiral twisting consists in
its base being somewhat bent ; the point however somewhat sinks, so
that it represents the figure of an S. (f. 16. a section ; a , ö, the valves ;
b, b, the two exterior setae lying in it ; c, the central one).

The description of the aculeus of the Cicada still remains. Its form
in C. Fraxini is as follows : the large triangular dorsal plate of the last
abdominal segment (PI. XXIV. f. I.A.), which at its apex is bent
down, covers from above the two double-jointed sheaths (the same, b.
and c.). Both joints are connected together by a soft membrane ; the
basal joint (f. 2. b. b ) is broader, shorter, and hollowed out ; the last
joint (the same, c. c.) is longer, narrower, towards its apex somewhat
broader, triangular, within hollowed in a channel. This last joint is
free, but the first is connected by a joint to the ventral plate. Between
these lie the aculeus (the same, d.), a horny, round organ, a little
dilated at its base, and near its apex compressed, where at the edge it
is toothed ; and this again consists of three horny ridges connected by
soft membrane. A still larger one (f. 3, a, a, seen from beneath, f. 5
from above), broader in front, and there likewise toothed at the margin,
lies above and forms the channel ; two finer narrower ones, pointed at
the apex (f. 3, 6, b, from beneath, and f. 4 from above) lie in the pre-
ceding, and project beyond it at the end, forming its apex (the same,
f. 2 d.). They all form combined a tube capable of distension, in which
doubtlessly the eggs are pushed down by the valves themselves after
the aculeus has pierced the vegetable substance, for which purpose
evidently it is armed at its apex with the strong teeth.

This, therefore, is the structure of the ovipositor in the different
groups of insects : in its investigation we have concluded our exami-
nation of the female sexual organs, and pass now on to the male organs.

Biblia Naturae, PI. XVIII. f. 3.

f Gen. Crus, et Ins., vol. iii. p. 242.

200

ANATOMY.

II. Of the Male Organs of Generation.

§ 146.

We have already indicated that the male sexual organs consist
essentially of the same parts as those of the female. They also are
divided into interior and exterior ; the former of which comprise the

TESTES, VASA DEFERENTIA, VESICA SEMINALIS, and DUCTUS EJA-

culatorius seminis ; and the latter, the penis and the prehensile
organ connected with it, and placed at the sexual orifice. We will
therefore now proceed to the consideration of the internal male organs
of generation.

A Internal Organs of Generation.

§ 147.

THE TESTES.

The testes are glandular white bodies generally present in pairs, and
which secrete the spermatic fluid. They regulate themselves in form
and structure according to the differences presented by the glandular
organs in insects in general, so that the majority are long convoluted
vessels ; some take the form of fasciculi of blind filaments, and a few
lastly appear as round glandular bags. Their structure is regulated by
their exterior appearance. Vascular testes have, like all the glands
of insects, two tunics ; the internal loose mucous one displaying a
parenchymatous appearance, the exterior one smooth, but coarser in
structure, and corresponding with the exterior muscular membrane of
all internal organs. Round testes have likewise a smooth coating,
which enclose a multitude of small vesicular bags in the cavities of
which the sperm is secreted.

As the testes are analogous to the female ovaries, we should conceive
that they as well as the latter should stand in connection with the
dorsal vessel ; but this has not yet been detected, although many forms
of testes extend in delicate filaments upwards which may apparently
be the indication of such a communicating thread, as is the case in the
ovaries. The analogous importance of both organs, which is most strongly
proved by the progressive metamorphoses of insects, to which we shall
subsequently return, is evinced also by the situation of the testes in the

MALE ORGANS OF GENERATION.

201

abdomen, as they occupy precisely the same place possessed by the
ovaries of the female, namely, the lateral spaces in the abdominal
cavity contiguous to the intestinal canal, yet inclining more towards
the venter. Those only which are united into one testis lie directly in
the middle of the body immediately beneath the nutrimental canal.

With respect to their precise shape, having thus indicated their most
general differences, and distinguished them as tubular or vesicular, they
may be arranged under several chief forms with various subordinate
differences, which the following classification endeavours to display.

I. Simple testes. The long testes which, in the early stages, are
divided, approach more closely together in the progress of development,
and, lastly, in the pupa state, unite into one single globular testis,
(PL XXIX. f. 1.) the earlier separation of which is indicated by a ring
upon its surface. Each of the hemispheres divided by this ring has its
own peculiar duct, which unite afterwards together.

This structure of the testes is peculiar to all the diurnal, crepuscular,
and nocturnal Lepidoptera, as well as the Pterophori ; other moths
(the Tinea) have them always separated. This testis consists, upon
closer inspection, of a thick cellular mass, which is pierced everywhere
by delicate ramifications of the tracheae.

II. Separated testes. The testes remain during the whole
course of the insect’s life separated from each other, and lie on each
side of the intestinal canal.

A. Simple vascular testes. Each testis is a simple filiform or
wider vessel, which lies either extended at full length, or makes convo-
lutions, but it sometimes is entangled in a hank.

1. Testiculi lineares (PL XXIX. f. 2.). They lie stretched out,
and are wid^r than the ductus ejaculatorius into which they pass by
means of a sudden constriction, and run upwards in a conical point.
(Libellula .)

2. Testiculi clavati. (PI. XXIX. f. 3.). Each testis is an obtuse
club, which gradually contracts itself into the ductus ejaculatorius, and
thus imperceptibly passes into it. ( Cercopis , Tinea.)

3. Testiculi filiformes . (PL XXIX. f. 4 ). The testis is a twisted
filament, which lies wound up in the abdomen, and, before it passes into
the duct, distends into a longitudinal sperm bladder. ( b . Tipula.)

4. Testiculi spirales. (PL XXIX. f. 5.). They distinguish them-
selves from the preceding merely by each filiform testis being twisted

202

ANATOMY.

spirally, and originating in a superior free and very fine filament.
( Ranatra .)

5. Testiculi furcati. (PI. XXIX. f. 6.). The testis here is also a

twisted canal, which furcates at its extremity and extends into two
short capitate ends *. ( Apis mellifica.)

6. T 'esticuli convoluti. (PL XXIX. f. 7-)* The filiform testis is
very long, much longer than the abdomen, and convoluted into some-
times a round ( Dyticus ), sometimes ovate ( Calosoma ) ball. ( Carabodea
Hydrocantharides .)

B. Compound vascular testes. Each testis is a bundle of
shorter or longer filiform or filamentary blind vessels, or bags, which all
unite into one common duct.

1. Testiculi scopacei. (PI XXIX. f. 8.). The short blind processes
which the testes form, are of equal length, and sit close together upon
the upper side of a common duct. ( Hydrophilus .)

2. Testiculi fasciculati. (PL XXIX. f, 9.). The somewhat longer
blind processes are tolerably equal in size, and are seated contiguously at
one spot, namely, at the end of the funnel-shaped distended sperm duct.
( Buprestis Trichodes, Clerus, Epidydimis in Locusta, PL XXVIII.
f. 5, a.).

3. Testiculi stellati. (PL XXIX. f. 14.). From the end of the
simple sperm duct, short fine, star-shaped or radiating filaments
originate. ( Apate .)

4. Testiculi flosculosi. (PL XXIX. f. 15.). The filaments at the
end of the sperm duct are here short, distended bags, which are placed
around the distension of the sperm duct, like the petals of a flower of
the class Syngenesia. ( Asida , Tenebrio, (Edemera.)

5. Testiculi imbricati. (PL XXIX. f. 10.). Short purse-shaped,
smooth pockets, which pass over each other like tiles, clothe a broad
compressed bag, which runs out into a short, at first serpentine sperm
duct. ( Locusta viridissima.)

C. Compound vesicular testes. Each testis consists of oval or
round and large or small vesicles, which unite either by degrees together,
or at one end of the there distended sperm duct.

1. Testiculi racemosi. (PL XXIX. f. 11.). The bladders are

* Suckow, in Heus. Zeitschr. f. d. Org. Physik, vol. ii. p. 234. PI. XII. f. 30.
According to Swammerdamm, Biblia Naturae, the testes are kidney-shaped bodies.

MALE ORGANS OF GENERATION.

203

tolerably large, pear-shaped, and open by degrees, sometimes several
together, into the common sperm duct. The lower bladders are larger
and longer stalked. ( Staphylinus .)

2. Testiculi granulati. (PI. XXIX. f. 12 and 16.). The end of the
sperm duct is dilated into a bladder, which is entirely covered with
round, button-shaped blisters. ( Blaps , Pimelia, Musca.)

3. Testiculi vesiculosi. (PI. XXIX. f. 13.). The long testis con-
sists of several rows of little bladders, which are placed around the
extremity of the sperm duct. In Semblis there are three rows of such
bladders present.

4. Testiculi vesiculoso-cirrati. (PI. XXIX. f. 7- &.). The reflected
end of the sperm duct bears several petiolated, larger, capitate bladders,
and between these there are fasciculi of smaller, ramose vessels, the
extreme ends of which originate from four delicate glandular bodies.
(Silpha obscura, according to Leon Dufour.)

D. Capitate testes. The testis consists of several sometimes
round or long kidney-shaped glands, which lie at the end of the
common sperm duct, or each duct bears but one such glandular body.

1. Testiculi capitato-simplices. (PI. XXIX. f. 17-)* Each testis
consists of a single, differently formed glandular body. In Lytta and
Meloe, this body is globose or uneven and granulated (f. 17-) ; in
Sialis, Phryganea, and Apis (according to Swammerdamm), it is
kidney-shaped, and the duct opens at the spot where the kidney is
emarginate.

2. Testiculi capitato-gemini. (PI. XXIX. f. 18.). The sperm duct
is furcate, and each branch bears a similar round glandular testis.
Donacia and Callichrorna have equal branches : in Lamia cedilis, the
superior one is longer (f. 18).

3. Testiculi digitati. (PI. XXX. f. 1.). At the end of the sperm
duct there are five conical glandular bodies, which extend in long
serpentine fine vessels. ( Nepa .) This form is as it were intermediate
between the capitate and vascular testes.

4. Testiculi capitato-compositi. (PI. XXIX. f. 19 and 20.). The
sperm duct gradually divides into several branches, each of which
sends off one ( Cetonia Prionus) or several capitate testes. ( Lepisma
Cicada .)

5. Testiculi capitato-verticillati. (PI. XXX. f. 2.). Each testis
consists of several globose frequently-compressed glandular bodies,

204

ANATOMY.

concave in the centre, each of which has its peculiar duct. All the
ducts are of equal length, and unite at one and the same spot to a
common sperm duct. The number of glandular bodies varies : we find
six in Meloloniha vulgaris and Oryctes nasicornis, nine in Trichius
fasciatus , and twelve in Tr. nobilis, on each side. This form appears
to be the most complete of all, whence it is peculiar to the beetles only.

§ 148-

THE EPIDYDIMIS.

The epidydimis is likewise a glandular organ frequently formed
upon the type of the true testes, and opens with a peculiar either
narrower or wider duct into the common duct of the sexual organs.
We find this organ in a few beetles only: its function also is not dis-
tinctly known ; the few hitherto observed forms are the following.

We observe the epidydimis most distinctly in Hydrophilus piceus
(PI. XXX. f. 3). They are here two long oval pointed bodies, turned
back about their centre, which contain within an exterior fine tense
skin a second glandular one, forming many rather long and regularly
successive little bags. Upon a first inspection, this body appears, from
its narrow, contiguous and parallel bags, as a convoluted vessel, and as
such Suckow erroneously explains it *. From this organ there
originates a long broad bag, with at first a narrow but suddenly
distending orifice, which appears to be formed like the tracheae of a
spiral filament, but, upon closer investigation, displays a structure
similar to the epidydimis. It also consists of two membranes, of
which the inner parenchymous mucous membrane likewise forms
narrow, parallel bags, which I almost consider as the actual secreting
cavities. In them we find a yellowish finely granulated liquid, the
secretion of this epidydimis. Both these bags (PI. XXX. f. 10. aa.aa .)
open at the end of the common duct in front of the sperm bladder.
(The same, a *. a *.) They are somewhat longer, or certainly quite as
long as the testes with the sperm duct, and extended they are of about
the length of the abdomen, but they are usually rolled spirally. Similar
appendages are found in Lytta and Meloe, but the epidydimis here is
a serpentine, lace-shaped vessel, which, upon the ventral side, empties
itself into the vesicular distended point of union of both the conical

* In Heusing., vol. ii. p. 232.

MALE ORGANS OF GENERATION.

205

sperm ducts*. In Trichodes, the epidydimis is also a simple, very
much convoluted vessel, without distension or appendages f.

In Locusta and Gryllotalpa , the epidydimis forms a convolution of
vessels. In Gryllotalpa, each of the four thick testicular bodies
appears to consist of one convoluted vessel. The superior one or
epidydimis is smaller, conical, and provided at the end with a long free
filament ; the lower true testis is larger and kidney-shaped. Both
display upon their surface evident windings of vessels, which are
surrounded by a darker mass. Their ducts unite beneath the large
testis into a small sperm bladder, into which also the thick convoluted
gluten vessel empties itself + . In Locusta, each epidydimis consists of
two divisions : the upper one ( a .) is a fasciculus of long, snow-white
convoluted vessels, which all unite by degrees into a tolerably large duct ;
the lower one ( b .), on the contrary, is an oval bag, the superior surface
of which sends off short round, tolerably narrow, filamentary processes.
The sperm duct empties itself into the neck of the bag, but the duct
of both bags, as well as the short one of the upper fasciculated
epidydimis, form likewise two short tubes, which speedily unite with
the broad, almost bag-shaped ductus ejaculatorius. At this point of
union, we find on each side a small round little bladder, which is the
vesica seminalis.

These are the different forms of the hitherto observed epidydimes :
other vascular appendages of the male sexual organs we shall shortly
investigate, and discern in them gluten organs.

§ 149.

THE VASA DEFERENTIA AND VESICA SEMINALIS.

The ducts which connect the testes with tbe common ductus
ejaculatorius, are called vasa deferentia, or sperm ducts. They are fine
tubes, originally of very small circumference, which either retain a
uniform size, or distend in front of their orifice, and widen into an oval,
long bladder. This distension is called the vesica seminalis or sperm
bladder.

We can speak only of the number and length of the sperm ducts.
With respect to their number, we observe where several testicular bodies
are found. There are also at first several sperm ducts, all of which, either

* See Brandt and Ratzeburg Arzeneithiere, vol. ii. PI. XIX. f. 12 and 13. e. e.
f Suckow, as above, PI. X. f. 5—7. + Ibid. PI. XII. f. 20.

206

ANATOMY.

by degrees or at one spot, unite into one common duct. The first case
is found only in the compound capitate testes ( T '. cap. composin'), but
universally here. Thus the twelve ducts of the twelve glandular
bodies of Cetonia aurata unite by degrees to a common sperm duct ;
indeed some of them previously unite together before they empty
themselves into the common duct. In Prionus (PI. XXIX. f. 19.) the
single ducts empty themselves alternately into the end of the common
sperm duct ; the same in Cicada, Latr., in which each branch bears
several glands. The second connection of the sperm duct is peculiar
to the verticillate testes : here all the single sperm ducts unite at the
end of the common duct, consequently at one spot. It is similar in the
double testes ( T . cap. gemini), where consequently the sperm duct
furcates at its extremity ; the same in Blaps , where two equal branches
are found, each bearing a testis, and then a third, longer originating
from the fork, which, however, bears no testis. The length of the
sperm ducts is subject to no less variety. They are short in all those
instances where they do not exceed the length of the abdomen, and,
consequently, make no convolutions, as for example, in Lucanus ,
Hydrophilus, Locusta, Callichroma , Libellula, Nepa, and, in general,
where there are large testes ; moderately long, that is, from twice to
three times the length of the abdomen, they are found in those instances
in which the different appendages we are about to describe are wanting,
for example, in Semblis , Sialis, Phryganea, and Cercopis ; long or
very long in those testes which are smaller and composed of several
bodies, or in general of a convoluted canal, for example, in Dyticus, in
which they are about five times as long as the body, and, like the
testes, convolute themselves into a small knot (PI. XXIX. f. 7* b.) ;
then in Necrophorus and Blaps eight or ten times as long ; in Cicada ,
Lat. fourteen times as long ; and in Cetonia aurata , nearly thirty
times as long. A short but very broad and indeed gradually distending
sperm duct is found in Meloe and Lytta (PI. XXIX. f. 17. b.), whilst
in other cases it maintains a uniform compass.

The sperm bladder has generally a more muscular structure than
the sperm duct. The size is proportionate to that of the testes, and is
wholly wanting to the less compact sexual organs, where the narrow
sperm duct passes into the common ductus ejaculatorius without any
distension. It is wanting, for example, in the Carabodea and Hydro -
cantharides , in Lucanus , the Capricorn beetles, all Lepidoptera,
Libellula , Cercopis, and several others 3 as a slight distension at the

MALE ORGANS OF GENERATION.

207

end of the sperm duct, it appears in the Lamellicornia , in Semblis ,
Tipula ; as a large ovate distension, at the end of the sperm duct in
Hydrophilus (PI. XXX. f. 10.) and Apis; as a peculiar appendage to
the sperm duct, in Phryganea (PI. XXX. f. 6. b.b.). In Lytta , Meloe,
and many others, we find but one sperm bladder, which has originated
from the union of both the sperm ducts; into this the lace-shaped
epidydimis then empties itself.

§ 150.

PECULIAR APPENDAGES.

We perceive appendages to the male organs similar to those glandular
ones we noticed above in the female sexual organs. With respect to
their peculiar purpose, we know certainly as little as of the true
function of the vessels accessory to the female organs ; but it is just
as probable that here as there they are gluten secreting organs, and,
consequently, glandular. That such appendages are not absolutely
necessary, is proved by the circumstance, that, as in the female, so also
in the male sexual organs, they are frequently entirely wanting, and
that sometimes they correspond in both sexes, as in Musca , Dojiacia,
Semblis ; in other cases are found only in the female, as in Tipula ,
Ephemera , and Nepa ; and in others again are found in the male
alone, as in Pterophorus and Cercopis. This deficiency of them in
one sex, when present in the other, speaks against the opinion of
Suckow*, according to whom they secrete urine; for this would
necessarily be peculiar to both sexes, but which does not invalidate
their being gluten secreting vessels of the sexual organs, which in
general in male individuals are much more numerous, and are of a
different form and situation to those found in the female. These
appendages are also found where urinary organs show themselves, as in
the Carabodea and Hydrocantharides. Comp. § 114.

If we more closely investigate the number and the form of these
appendages, their first and most important character is their almost
symmetrical situation and equal number. Tipula and Blatla only, as
far as our knowledge extends, make an exception to this rule ; as in
Tipula (PI. XXX. f. 14.), according to Suckow, an uneven clavate
process is found at the point of union of both sperm ducts, which,
according to all analogy, can be explained only as a gluten organ.

Housing., vol.ii. p. 248.

208

ANATOMY.

particularly as in many other insects the same part appears in a similar
form. In Elatta, according to Gaede *, there is a large bladder at
this precise spot.

The symmetrical gluten organs are, in the first place, double, and,
indeed, short clavate processes, which, at the point of connection of the
sperm duct, empty themselves into the ductus ejaculatorius. We thus
find them in Sialis , Ephemera, Lepisma, Nepa , Apis (PI. XXX. f. 8.),
and Piophila casei , Meig., in which, however, the clavate bag has a
lateral pocket. In the Carahodea and Hydrocantharides, it appears
longer, indeed as long as the abdomen, proportionately narrower, and
already making some windings. In the former, at least in Calosoma
sycophanta, each bag is flat, somewhat depressed from its apex, spirally
convoluted, and into it, shortly before its termination, the sperm duct
empties itself (PL XXX. f. 13.) ; in Dylicus, on the contrary, it is
round, irregular, twisted, and with _its opponent, as well as with the
sperm duct, it is bound together. Still longer, and, consequently, more
twisted, but otherwise uniform, they appear in Gryllotalpa , where
they are at least twice the length of the short testes in Stratiomys ,
it is once and a half as long as the testes and the sperm duct j in Tinea ,
equally long, but narrow and filiform. In all these cases, they unite
with the sperm duct at one spot, to form a common ductus ejaculatorius.
Longer than the testes, but likewise thin, narrow, and filiform, we find
them in the Lepidoptera : here, consequently, they make several
turnings, and then empty themselves in the sperm duct itself, a short
space before its union with the ductus ejaculatorius. (PI. XXX. f. 12.)
The Lamellicornia possess the longest. They here appear as two long
narrow, much convoluted filiform vessels (PI. XXX. f. 9. b.~), which,
towards their base, distend into a long oval occasionally broad bladder
(Melolontha), which, together with the sperm duct, passes into the
common duct at one spot. The length of this vessel is sometimes con-
siderable ; for example, in Oryctes nasicornis, about twenty times as
long as the body, but in Cicada, Lat., where we observe similar vessels
only five times as long.

The ramose is the last form of the single-paired gluten organs.
We have already observed such in the female appendages in Elater
and Hippobosca: among those of the males, we find them in the
Capricorn beetles. In Callichroma moschatum, I found a thick tangle

Beiträge zur Anatomie der Insekten, p. 20.

MALE ORGANS OF GENERATION.

209

of very fine vessels, which, upon opening the insect, was covered by the
dorsal portion of the posterior end of the intestinal canal. Upon closer
inspection I found that all these vessels were merely the branches of a
main stem that was furcated, which was the case also with each branch,
and I thus found eight successive furcations. The terminal ends I could
not distinctly perceive, but they are probably loose. In Lamia cedilis ,
at least, where only one furcated vessel is found on each side, the
branches are free, but unequal, the exterior one being shorter, and the
interior longer, the stem emptying itself into the sperm duct (PI. XXX.
f. 11.) ; and it is the same in Callichrorna moschatum.

Where there are two pairs of appendages, they display the same
forms. In Ascalaphus Italiens they are, according to Hegetschweiler,
four unequal, pear-shaped bladders, which empty themselves into the
sperm duct : the smaller ones have besides a superior vascular
appendage. According to Posselt *, two pairs of vascular appendages
are found in Geotrupes stercorarius ; to Hegetschweiler, in Clems
alvearius ; to Gäde, in Tenebrio molitor ; and also in B laps mortisaga,
Meloe and Lytta, in which they are short, but of unequal length, and
one pair empties itself upon the upper surface, and the other pair upon
the under surface, into the sperm bladder f. In Hydropliilus, there
are also two pairs of unequal appendages ; the inner ones are shorter
but broader, the exterior ones longer, and they furcate into two equal
branches : both empty themselves between the sperm ducts, the testes,
and the epidydimis, into the end of the common ductus ejaculatorius.
(PI. XXX. f. 10. b. b. and bb. bb.).

In Notonecta glauca there are even four pairs of equal vascular
appendages; and in Buprestis mariana, according to Gäde X, there
are two pairs of vesicular ones and two pairs of vascular ones together.
One pair of the first is very small, the other longer, clavate, and bent :
also one pair of the vessels is bag-shaped, and the other filiform and
tolerably long. All unite at one spot in the ductus ejaculatorius, into
which also the sperm ducts, but at some little distance further back-
Avards, empty themselves.

* Beiträge zur Anatomie der Insekten, Pt. 1. f. 16.
t" Brandt and Ratzeburg Arzeneithiere, vol. ii. 4 Pt. PI. XIX. f. 13.

+ Nova Acta Phys. Med., vol. xi. p. 331.

210

ANATOMY.

§ 151.

DUCTUS EJACU LATORIUS.

The ductus ejaculatorius seminis is that tube which extends
from the point of union of both sperm ducts or sperm bladders to the
commencement of the penis. It displays in its structure coarser
muscular fibres, and is of a more compact nature than the sperm duct.
It is analogous to the egg canal of the female organs, and appears
sometimes, like this, vesicular ( Hydrophilus ), and sometimes contracted
by degrees, consequently clavate ( Lucanus , Lytta ), sometimes simple
and of equal width. In length it varies much, sometimes short,
scarcely visible, yet broad (Locust a, Gryllotalpa) , sometimes longer,
but yet, in proportion to the other internal sexual organs, still short
( Calosoma , Melolontha , Trichius) ; moderately long when it attains
about the same length as the sperm ducts (Hydrophilus, Lytta , Meloe ,
Papilio) ; long, lastly, when it is longer, indeed considerably so than
the sperm ducts ( Lucanus , Lamia'). The most remarkable form of the
ductus ejaculatorius I observed in Lamia cedilis. In this it is about
eight times as long as each sperm duct, and geniculated. But to display
this remarkable structure most justly, I must extend my description to
that of the entire sexual apparatus.

If a male Lamia cedilis be opened from its back, we first observe in
the centre the convoluted intestine, and contiguous to it, on each side,
about the centre of the lateral space, two W’hite testes. Both unite into a
narrow sperm canal, which runs towards the anus, and there unites itself
with the opposite one of the other side, after each has received a furcated
gluten gland. After a short course in a direct line, the ductus ejacula-
torius bends forward, runs in a serpentine direction up the central line
as far as the abdominal nervous cord, but beneath the intestinal canal,
as far as the thorax, and here again bends a second time, turning upon
itself like a knot, it then runs back again in a gentle curve to the anus,
there to pass into the penis. From its first bend, this duct is no longer
free, but it is enclosed in a wider membranous tube, into which also pass
eight delicate tracheae, the fine ramifications of which spread upon the
duct, and accompany it as far as the second bend, after they having one
after the other previously dispersed themselves in fine branches. But
from its second bend, the ductus ejaculatorius is accompanied by a strong
horny ridge, which lies in the superior portion of the enclosing tube,
retaining it tensely distended, and which terminates only where it passes

MALE ORGANS OF GENERATION.

211

into the penis. In the other capricorn beetles (for example, Callichroma
moschatum,) the ductus ejaculatorius is indeed much shorter, but like-
wise twice geniculated. That portion from the point of connection to
the first knee is wider, more vesicular, and transversely ridged, taking
the place of the sperm bladder, which is wanting, to the equally wide
sperm ducts ; the other, double as long but much narrower portion,
bends forwards as far as the commencement of the sperm bladder,
re-bends back to the anus, and then passes into the penis, having
reached the spot of its first geniculation. The penis, or rather its
exterior case, is united to this first knee by means of a muscle.

We are as yet unacquainted with other remarkable or peculiar forms.

B. External Organs of Generation.

§ 152.

THE PENIS.

Having already perceived a great variety of form in the female
external organs of generation, we might expect to find this still more
extensively the case in the male organs, had their parts been as widely
investigated and described. But that which does not invite close
inspection by its exterior or the problematical nature of its form, but
much rather withdraws itself from the eye of the inquirer, and is con-
cealed upon a first superficial examination, does not so easily excite
curiosity and stimulate the desire for instruction, because it is not sup-
posed to exist. This is the reason why the structure of the penis has
been made less frequently the subject of description than the female
ovipositor, although possibly there is no other so variously formed
an organ, nor one subjected to such characteristic and generic dif-
ferences.

The penis of beetles consists essentially of two parts, namely, of the
exterior horny case analogous to the bone in the penis of the dog, and the
internal delicate membranous penis itself, which admits of being consi-
dered the free ductus ejaculatorius. The exterior sheath alone is visible
upon a first examination, as it entirely covers the internal tube and allows
it only at its apex, where it is divided a little, to project. This sheath is
clothed, either entirely or partially, by a delicate membrane (the pvce-
putium), which may be considered as a continuation of the inner mem-
brane forming the cloaca. This membrane has also sometimes horny
ridges to support it. Thus much upon the penis in general; more will

p 2

212

ANATOMY.

be derived from the following particular description of it in individual
insects.

In Carabus ( C . glabratus, Fahr., PI. XXV. f. 1 — 4.), in which the
withdrawn penis extends to the commencement of the thorax, the prae-
putium extends only to the end of the fourth segment (the last connate
one counted as two) ; it is wide, bag-shaped, truncated at its extremity,
and is supported by two fine bones, which have the same shape as the
bag- At the base both bones lie closely together, but they with their
shanks so separate that the two shanks of the upper one pass to the
upper valve of the cloaca, and those of the lower one to its lower valve.
The basal portion of the penis projects beyond the upper portion of the
bag, driving this before it, so that it is covered by a continuation of it.
Besides, the sides of the bones stand in close connection with the exte-
rior integument by means of muscles, which hold the prepuce back
when the penis is pushed forward. Three horny pieces are also found
in the case of the bag, one heart-shaped one beneath, exactly between
the shanks of the bone, and the two others at the apex of the upper
portion which clothes the free part of the penis. There are likewise
bony processes which support the case of the produced part of the bag,
and stand in flexible connection with the horny sheath of the penis.
The apex of the produced portion of the bag is divided where the upper
end of the penis lies, and through this aperture the ductus ejaculatorius
seminis passes into the latter.

The penis itself is a gently bent, horny cylinder, above round, dis-
tended towards its end, and flattened with obliquely truncated extre-
mities ; upon its lower or ventral side it has a longitudinal aperture,
which is surrounded by a callous margin, which indicates the outlet of
the ductus ejaculatorius.

Dyticus (PI. XXV. f. 5 — 10.) displays already important differences.
The two valves which form the cloaca are much larger, the upper one
is soft and ovate, the lower one harder, larger, and longitudinally
divided into two lobes. Both lobes are placed upon a transverse horny
piece, one wing of which encompasses the exterior margin of each lobe,
and is bound to it as well as to the ventral plate by strong muscles.
The prepuce of the penis lies between these two valves, which, as
in Carabus, is a membranous bag, but the horny bones of which are
differently formed, and display stronger muscular connections. The
prepuce itself is held distended by two horny pieces. A broad horny
arch, shaped to the bag, surrounds its whole circumference, but lies

MALE ORGANS OF GENERATION.

213

lower down, so that the withdrawn penis projects beyond it ; the upper
margin of this horny arch is somewhat reflected, and forms two pro-
cesses, to which muscles are attached that assist to push the penis
forward (PI. XXV. f. 7* a, a). The second flat longitudinal horny
piece lies in the lower part of the bag between the shanks of the arch
(PI. XXV. f. 6. b). If the prepuce be opened we first meet with the
horny sheath of the penis, a bilobate organ gently bent from right to
left, between the valves of which lies a similarly bent and pointed
horny spine. Both valves are closely connected by membranes and
muscles, and are themselves enclosed in a membranous sheath (PL
XXV. f. 9. a.), which is withdrawn by means of a fine horny bone
flattened at its end ; it so lies between the prepuce and the penis that
it retains the skin when the muscles push the penis forward. The
valves of the penis are thickly beset, upon the bowed inner margin, with
long setae, which are placed in a close row, as is also the inner spine.
This spine has, similarly to the above-described female ovipositor, an
excavated channel, in which lies a fine lancet-shaped bristle ; both are
connected together by means of flexible skin and muscles, and between
the bristle and the channel is the outlet of the ductus ejaculatorius.
This spine therefore is the true penis, and the two valves are its case.

The penis of Hydrophilus (PL XXV. f. 11 — 14.) approaches very
closely in many particulars to that of Dyticus. The prepuce here also
is a truncated bag, from the upper surface of which the penis projects.
In the lower part of the bag lies a broad, shovel-shaped, horny plate,
from the margins of which on each side a bone originates, which form
the lateral limits of the bag ; upon the upper side, at the end, lies a
triangular perforated valve, which forms also the superior valve of the
anal aperture, and sends off two free lateral processes to the bone of the
lower portion (c, c ). The cloaca penetrates beneath this valve, and is
separated from the penis merely by a fold of the prepuce. The penis
itself consists of the bivalved sheath and the unequal spines lying
between them. Upon the inferior side the valve borders upon a heart-
shaped horny plate (g), which appears to form the support of the entire
organ ; its lateral margins turn upwards, and a coarse skin is attached
to it, which closes the canal of the penis from above. The valves (e, e,)
of the penis itself are pointed downwards, they are bent, concave, horny
bones, which are internally filled by membrane and muscles, which
unite to them the central spine of the penis. The most central spine
(f. f,) is not bivalved, as in Dyticus, but a perfectly closed tube, at the

214

ANATOMY.

under surface of which runs a narrow spatel-shaped horny bone, and
there is a hair-shaped one at its superior surface ; the aperture (.*) is
enclosed by two small horny arches.

In Melolontha the penis is only half covered by the prepuce ; its
case is posteriorly, particularly upon the upper surface, entirely horny,
and distended like a bladder ; two processes originate from it, which
are nearly conical, somewhat sloping, and furnished anteriorly with a
knob ; these are contiguous beneath, and above they are united by a
strong membrane : between them lies the membranous canal of the
penis, which consists of several folds of the ductus ejaculatorius *.

In Callichroma moschatum the prepuce is a thin cylindrical bag,
which in front is obliquely truncated, and it terminates above with a
triangular horny plate. At each of its lateral angles a bone originates,
which inclining forwards proceeds beneath to unite itself there with the
corresponding one of the other side, forming a perfectly horse-shoe-
shaped arch. The case of the penis, which is similarly shaped, lies
entirely enclosed within this prepuce ; it is likewise more membranous,
but terminates in front with two horny valves, the broader and lower one
of which entirely embraces the narrower superior one upon the lateral
margin, and sends forward two flat processes into the skin of the case.
The membranous canal of the penis lies within this case, as a continua-
tion of the ductus ejaculatorius (PI. XXVI. f. 1 and 2.).

Among the Orthoptera we find in Blatta the penis perfectly unsym-
metrical. The sexual organs are only visible upon the removal of the
dorsal plate, for they lie concealed between the two last ventral plates,
and are protected on each side by the short, jointed processes ; we then
observe a triangular irregular valve (PI. XXVI. f. 17, 18. a), which
covers the passage to the sexual aperture from above, and contiguously,
two other, likewise unequal, bags (the same, b and c), which protect the
sides, and lastly, beneath, a hook bent upwards obliquely over these
parts (the same, d, d). Upon closer examination the superior valve
displays itself as a triangular membranous lobe supported by several
horny pieces, at the anterior apex of which there is placed a stiff horny
hook, which is curved backwards (PI. XXVI. f. 5). The inferior
valve, standing opposite to this superior one, is a flat horny plate (f.
(). a), with which laterally the right dorsal valve which bends upwards
(f. G. />) is united by means of a flexible membrane. The yet remain-

* See Straus, as above, PI. HI. f. 5., PI. V. f. 1—3., and PI. VI. f. 1.

MALE ORGANS OF GENERATION.

215

ing portion of the visible sexual organs is the penis (f. 7)> consisting of
a superior sheath formed by two horny pieces, which are united by a
membrane (f. 7* «,) and the central unequal upwardly bent spine,
which is furnished at its extremity with a barb (f. 7* b.').

The comparison of this organ with that described in the Coleoptera
has therefore now no further difficulty ; the superior and inferior valves
are the case of the penis, here indeed entirely transformed, which is
united by the withdrawn prepuce to the surrounding parts ; the penis
itself lies formed in it, at least in situation, just as we have described
it in Dyticus and Hydrophilus.

In the Hymenoptera I shall first describe the penis of the saw-flies.
When in a Cimbex the last ventral and dorsal plates are removed, upon
the dorsal side we immediately meet with the flexible anal valve, be-
neath which the anus lies, and then with a fold of the prepuce, which
separates the anus from the sexual organs. These are entirely enve-
loped in the membranous prepuce, and consist of two large hooked
horny bodies, which are united at their base by a flexible membrane ;
between these likewise lie the bivalved flexible penis, in which, pre-
cisely as in the female saw-flies, the central bone is wanting. The
particular form of each single joint is shown in the figures 8 — 10. of
Plate XXVI. The exterior valve consists of two joints (f. 8 and 10.
a , 5), the upper one of which is small, triangular, somewhat arched,
and membranous ; the lower one is larger, and consists of strong horn.
Between these lie the broad lobate valves surrounded by a horny ring
(f. 8 and 10. c, c), from which the canal of the penis (f. 10. dT) is con-
tinued.

In Vespa , where we find almost the same parts, we immediately
detect an important difference, which is, that the central unequal spine
of the penis, or here rather the true penis itself, is present. Figures
11 — 13. of PI. XXVI. show the male organs of Vespa Germanica.
Two large round valves, to which above there is attached a small
spinous process, form, as in Cimbex, the exterior case of the penis
(f. 11. a, a). Between these exterior ones the inner ones lie (the
same, b, b) ; these are smaller and more delicate organs, which embrace
the penis, they are of the consistence of parchment, and distended at their
end into a shovel shape. The penis itself is a delicate bent shovel,
which, previous to its dilatation, is provided with two barbs (f. 13. a,
a ), and has upon its superior side a deep almost tubular channel,
through which the semen is ejected.

216

ANATOMY.

The male organs of the Eepidoptera (for example, of Deilephila
Euphorbia, PI. XXVI. f. 14 — 17-) display two exterior horny valves
densely covered with scales ; these valves are attached to a projecting
horny ridge upon the circumference of the sexual organs (f. 14. a, a).
Beneath these exterior valves there are two interior finer, pergamenta-
ceous, and delicately haired ones, which, as well as the exterior ones,
correspond together at their internal margin, and on their external
margin they stand free. Each runs upwards in a sharp fine hook, and
has beneath also, contiguously to it, a membranous process, which par-
tially covers the penis (fig. 15. displays this inner valve from the
inside). The penis lies between these inner valves ; it is apergamen-
taceous somewhat bent tube, which is open and emarginate in front
(f. 15 and 17*)* Upon the upper side, opposite the valves, there is a
strong, bent, conical hook, which has anteriorly two points, an exterior
one which bends inwards, and an interior one which bends outwards,
and between the points a conical membranous process projects, which
is also perforated (f. 14. c), and forms the anal tube. Both organs,
the former internal valves supplied with a hook, and these hooks stand-
ing opposed to it, serve, without doubt, to retain the female organs
during copulation.

The male sexual organs of the Diptera have, in the majority of
cases, been noticed and figured by Meigen in his monograph of this
order * ; we can therefore give a more comprehensive description of
them than of the preceding ones.

We everywhere find exterior, and even often interior valves, and
between these the penis. The chief difference of this order is, that the
male sexual organs in most instances project beyond the apex of the
abdomen, and lie there exposed, which w7as not observed in the former
ones. We thence find the prepuce, or rather that membranous bag
which contains the withdrawn organs to be wanting in the Diptera.
The differences of the exterior valves is very great. In the family of the
Tipularia I formerly described a new insect ( Nematocera nubeculosa),
which w^as distinguished by large projecting sexual organs t. Two
thick, large, black, shining processes, each of which bears a small
bright brown reflected appendage, form the exterior valves, and be-

* J. W. Meigen’s Systematische Beschreibung der bekannten Europäischen, zweiflüg-
ligen Insekten, 6. B. mit Kupfern, 1818 — 32.

*|* Comp. Thon’s Archiv, der Entomologie, vol. ii. p. 36. PI. I. f. 13.

MALE ORGANS OF GENERATION.

217

tween them lies the short tubular penis. A very similar structure is
observed in the predacious flies, particularly Laphria and Asilus , yet
the large cylinder is bound by membranes to the ventral side, in which
shape it forms an actual bivalved sheath, and the exterior superior
smaller appendage is wanting. The sexual organs are most striking in
the Empidodea and Dolichopodea. In the former we observe at the
last abdominal segment of the male two large orbicular sloping valves,
which are fringed at their margin ; between their lower edges there is
a long, fine, upward bending bristle, which frequently lies completely
concealed between the valves. This bristle, in which we detect above
a fine channel, I consider as the penis, and the valves as its case. In
the Dolichopodea the last segment of the abdomen, turned downwards
towards the venter, forms the case, which is exteriorly convex but inte-
riorly concave. The upper free space of this cavity is occupied by a
horny bristle, which is so united by membrane to the case that it can
open and shut its aperture. In the thus formed cavity of the capsule
the penis lies. In front, attached to the capsule, there are two bent,
thickly fringed lamellae, completely resembling those of Nemalocera.
I am almost induced to consider them as the projecting inner valves,
but they evidently serve as retaining organs. The anal aperture
appears to lie at the base of these valves.

In the true flies ( Musca , for example,) the sexual organs are placed
at the ventral portion of the last abdominal segment, the ring of which
is hook-shaped, and by this curve covers the organs in repose; con-
tiguous to the apex of the hook there are two moveable, differently
formed valves, the analogues of the exterior valves in Dolichopus, and
in front lies the anal aperture ; further towards the venter, about the
middle of the hook, we find the sexual organs, likewise two either
longer or shorter bent lobes, between which a simple, thicker, some-
times clavate process (the penis) is displayed. Occasionally we find,
contiguously to theTarger ones, two small triangular valves, which may
be considered as the inner valves of the penis.

Among the Hemiptera, we discover in Cercopis sanguinolenta , both
in the male and in the female, two valves at the apex of the abdomen,
of which those of the male are considerably the smallest ; when opened,
we find at the base, between the exterior valves (PI. XXVI. f. 18.),
two smaller internal ones (f. 19. a, a), which are attached by articula-
tion to two horny bones. Between these the penis rises, and is, like
the ovipositor, a long, thin, setiform organ, which is not however, as in

218

ANATOMY.

the female, bent from below upwards, but from above downwards, so
that its apex is turned towards the venter. This point is broader than
the upper part, and apparently armed with barbs ; consequently, during
copulation this spine of the penis must penetrate the ovipositor of the
female if impregnation is to follow. This insertion, however, is only
made possible by the hook-shaped bend of the penis, and much faci-
litated when the male sits upon the female. The Cicada actually thus
copulate, but as their connection lasts long, and the constant weight of
the male would be oppressive to the female, the male descends and sits
by her side, when she reposes. In some genera of the Cicada, the
pronotum of which is decorated with processes and excrescences, which
project beyond the abdomen ( Combophora , Centrotus ), the first act of
copulation can only take place in this position of both sexes by the side
of each other, they have probably therefore a laterally bent penis for
this purpose, thus adapted like the downward bent one of the pre-
ceding.

We must lastly notice the male sexual organs of the Libellulce, as
the erroneous opinion has long been held that they were not placed at
the end of the abdomen, but at its base. This very naturally ori-
ginated from the observation that the male flew about with the female,
retaining her anal extremity by means of clasps affixed to the base of
the abdomen, and at the same time held her in the neck by the valves
of its tail, apparently occupied in copulation. But if we closely exa-
mine the economy of these insects we shall speedily observe that males
fly at sitting females and rapidly copulate with them, like the flies.
The preceding is merely an expression of mutual inclination which
announces itself by the male suddenly seizing the female by the neck
in the air, and thus flying off with her, whilst she, if willing to respond
to this attention, bends up her anal end to the male, and allows herself
to be there seized by the hooks lying at the base of the abdomen ; but
if not pleased with his caresses she does not bend her body up to him,
but hangs it freely and unparticipant downwards, and remains like a
prisoner attached to his chain.

The following is an accurate description of the male sexual organs,
as well as of the prehensile organ at the base of the abdomen.

We observe in the ventral plate of the ninth abdominal segment an
aperture closed by two valves (PI. XI. No. 3. f. 9. d ). If these valves
are removed we detect a small, delicate, horny ring, which surrounds
the aperture of a short membranous cylinder ; this cylinder is the penis,

MALE ORGANS OF GENERATION.

219

and the anterior aperture the extremity of the ductus ejaculatorius.
Hence the structure of the external sexual organ is as simple as that of
the internal ones (comp. § 147« II. a. 1).

The prehensile organ which lies in the ventral plates of the second
and third abdominal segments has, on the contrary, the following very
complicated structure. In the first place it consists of three divisions
(the same, 4 and 5. a, b, c), the two first of which are placed upon the
second abdominal segment, which apparently, at least laterally, consists
of two rings ; the third forms the ventral plate of the third abdominal
segment. The foremost division (the same, f. 8.) consists of six
horny pieces, two anterior triangular smaller ones (a, a), to which two
broad, thin, sithe-shaped hooks, which are bent backwards, are attached
(c, c ), and the two posterior ones (6, b ), which are harder and more
horny, and distend about the middle of the upper edge into two dentate
knobs. At d the anterior and posterior parts are jointed together
(f. 5. represents them extended, f. 8. as bent), and in the centre, be-
tween the two pieces of the two sides, there remains a deep unoccupied
cavity (f. 4). The second division (f. 4 and 5. b. and f. 7-) consists of
two pieces. The larger basal piece, or the ventral plate of the second
division of the second abdominal segment, is quadrate, provided at each
angle with a small process, which unites it with the preceding and
succeeding pieces. Its central surface is deeply excavated, but it rises
on each side to a strong obtuse point directed forwards (f. 7- a )> the
posterior edge of which is thickly beset with bristles. Between the
two points, consequently in the concave central groove, the second piece
lies, which is a geniculated, strong, horny hook (f. 7- &) i it is united
to the first by a joint, and ean, by means of muscles, be directed up-
wards or withdrawn within the groove. The third division (f. 4 and
5. c. f. 6.) is larger than the preceding, and appears as a bellied, ante-
riorly concave, horny knob (f. 6. a ), which is entirely filled with
muscles. These muscles serve to move the anterior hook-shaped ap-
pendage, which again consists of two parts, the large, bellied, double-
pointed hook (f. 6. b), and the thin, cylindrical, double-jointed pedicle
(f. 6. c, c) ; this hook, in repose, lies in the anterior excavation of the
horny bladder (f. 6. d), but when raised it stands free upon the two-
jointed pedicle. A long, thick, pointed, horny bone proceeds backwards
from the horny bladder, and it is this which forms the ventral plate of
the third abdominal segment (f. 4 and 5. c. e, e.).

But this entire prehensile organ is only seen when the reflected

220

ANATOMY.

margins of the dorsal plate are bent backwards ; it is therefore entirely
covered in dry specimens by these margins. Males may be detected in
dry specimens by their above thick and clavate abdomen and the larger
anal fangs.

III. Development of the Sexual Organs during the
Metamorphosis.

§. 153.

It is evident, from Herold’s * admirable investigation, that even in
the larva the germ of the future sexual organ exists, and indeed with
the distinctions of male and female. The larvae are born with these
extremely small and almost invisible germs, which develope themselves
in the course of its life, but most rapidly in its pupa state, until they
attain their perfect development upon the full growth of the insect.

If a caterpillar be opened from the back we observe, after the removal
of the fatty substance, upon the intestinal canal, at the posterior ex-
tremity of the large stomach, two small roundish or ovate bodies, from
which posteriorly two filaments originate, which unite into one canal
close to the anus, beneath the rectum. But these filaments are so fine,
or become so in their progress, that they almost entirely disappear, and
could not be followed to their termination by even the exact Lyonnet. If
several larvae, of different sizes and of different ages, be opened, we
soon detect differences in these bodies, for some (in Pontia brassicce )
are more cylindrical, and are divided by constrictions into four suc-
cessive vesicles ; the others are flatter, subsequently ovate, and by con-
strictions from the apex to the base divided into four equal lobes. In
the first instance they were small testes, and in the last the preformed
egg-bags or ovaries. This form remains unchanged until the pupa
state, merely increasing considerably in size.

In the pupa state the convoluted sperm ducts, and in the female the
gluten glands and ovaries, gradually develope themselves. In Pontia
Brassicce, upon which insect Herold made his observations, the testes
gradually approach each other until they lie contiguously. From this
common situation a closer connection is formed, the sides press each
other flat, and by degrees intimately join together. Thus, from the
earlier separate four-chambered testes a simple globose testis is formed,

* Entwickelungsgeschichte der Schmetterlinge. Kapcl and Marburg, 1815, 4to. with
plates.

ORGANS OF GENERATION.

221

which, however, probably still consists of two divisions. From the two
hemispheres two delicate canals originate, which, after many con-
volutions, unite into a thicker but frequently twisted duct ; closely in
front of this point of union there hangs attached to the sperm duct a
simple, long, twisted vessel, the gluten gland. The development of the
female organs displays itself most conspicuously in the enlargement of
the ovaries. They increase at the expense of the egg canal, which by
degrees disappears, whereas the egg bags become continually longer, and
twist themselves up spirally from the apex. The point of union of the
very short oviducts distends, and sends off on one side a pointed bag,
the spermatheca; opposite this a smaller vesicle is formed with a longer,
vascular, much twisted appendage: farther below, near the vagina,
there hang also vascular, long, and much convoluted gluten glands.
Both distend prior to their emptying themselves, and perforate the
vagina at one spot close to each other.

This is an abbreviation of the description of all the changes made
during the pupa state. In the caterpillar there were simple bodies
with simple delicate canals, these pass over unchanged in form into the
pupa, and undergo by degrees changes the results of which are the lastly
completed structure which we have here briefly indicated.

It is to be regretted that similar observations have not been made in
several insects, and although they would probably present the same
results, many attractive details worthy of observation might be pro-
duced. This refers particularly to insects with an imperfect metamor-
phosis. We may ask does the transformation of the sexual organs take
the same course, and the bodies present at the birth of the larva merely
enlarge, and only when the pupa displays the rudiments of wings
undergo a general change of form ? If we refer to the development
of the intestinal canal, which has, from the commencement, its perfect
form, we might feel inclined to adopt the same view of the sexual
organs : we must confess that this view appears the most natural,
because in insects with an imperfect metamorphosis the pupa state
appears to be of infinitely less importance, and that consequently the
changes in structure cannot be so great as there where the pupa sleep
steps in so abruptly between the preceding and succeeding active
periods. And may not possibly the lesser degree of importance which
the pupa state possesses in insects with an imperfect metamorphosis be
the consequence of their smaller change in the form and structure of
their organs ? Could not, therefore, as the change of the internal organs

222

ANATOMY.

is significantly less, and is indeed limited almost to tlie mere enlarge-
ment of the parts with their retained relative proportions, the change
also of the exterior form almost entirely disappear, and the whole
metamorphosis be restricted to a mere increase of size? Truly both
phenomena are dependent upon the same law, neither eventually con-
ditionates the other, but must proceed from the similar results of one
cause, which evidently lies deeply concealed in the mode of develop-
ment of the Articulata in general, so that where the one displays
itself the other must also be present and both synchronical, neither
the latter before the former nor the former before the latter.

IV. Conformity of the Female and Male Sexual Organs.

§ 154.

At their origin both kinds of sexual organs, as we have seen above,
appear under the same form. This same conformity, displayed at the
origin of the internal parts, is also subsequently verified in their
fully developed state. This law we laid down at first (§ 131),
for both systems have the same object, viz. the elaboration of the
productive fluid. In the female it is the ovaries where this fluid
is prepared, and in the male we call the same organ the testes.
Very similar ducts originate from these organs, and afterwards unite
and conduct by a single narrower canal their contents outwards. This
conformity of importance in the internal parts is still more strongly
proved by their forms frequently agreeing. Long cylindrical testes
correspond with long ovaries filled with the germs of eggs ( Libellulce ) ;
ramose bunched testes with similarly formed fasciculated ovaries
( Locusta , Gryllotalpa ) ; compound, radiating, and united testes with
similar radiating or twirling ovaries ( Lamellicornia ) ; indeed, some-
times the number of the single bodies in the testes agrees with the
number of the egg tubes ( Melolontha , Trichius). It is very natural
that the appendages should be differently formed, for their function
is different ; for example, the spermatheca of the female organs must
necessarily be wanting in the male, for they receive no sperm, but
only impart it : consequently the reciprocal conformity of the internal
organs is so evident, that it is difficult to doubt it ; but this is not
the case with the exterior organs. In these no endeavour has yet
been made to trace the parts of the one in the other sex. But if
the descriptions be compared which we have given of the male and

MALE ORGANS OF GENERATION.

223

female external organs, it will escape no one that this analogy is not
to be overlooked even here. The female vagina in every case consists
as well as the male penis of horny bones and ridges,, which are united
together by a flexible membrane. If these horny bones project beyond
the abdomen they form the aculeus, or ovipositor, which has in its
entire structure the most striking resemblance to the penis. Exterior
valves enclose in both organs an internal compound instrument, which
is, as in the grasshoppers, where we observe the ovipositor, either con-
nate with the exterior valve, or it remains separated, as in the bees,
wasps, and other Hymenoptera. If the structure of such a sting be
compared, for example, with the penis of Dyticus, we observe, even to
their smallest parts, the greatest conformity ; indeed, even the male
sexual organs of the wasp agree both in number and situation of the
individual parts wholly with the sting of the female. Henceforward,
therefore, it may not appear hazardous to assert that the ovipositor, by
its conformity in structure with the penis, is analogous to the clitoris
of the superior animals. This view, which as far as I know is here
propounded for the first time, may be liable to many objections, parti-
cularly by those who do not pass beyond forms, nor elevate themselves
to general simplifying and retrogressive ideas ; but they who study
natural bodies in conjunction with others furnished merely as orismo-
logical auxiliaries, and who are not merely acquainted with ten thou-
sand species, but endeavour also to discover the general results of their
various vital phenomena, will here discover a not wholly unimportant
contribution to the solution of this great problem.

We have above shown that the jointed ovipositor is no peculiar organ
belonging only to the sexual ones, but rather the mere apex of the
abdomen ; its divaricating in form therefore cannot be cited as a proof
against the opinion that the ovipositor is a transformed clitoris.

224

SECOND SUBSECTION.

THE ANIMAL ORGANS.

§ 155.

The animal organs forming the systems of sensation and of motion no
longer display a vegetable, but strictly a peculiar, purely animal character.
We have before seen (§ 91.) that the intestinal canal, the vessels, and
the sexual organs are mere repetitions of vegetable structure, in as far
as they consist, like plants, of cells, tubes, and thin membranes. But
we will now show that these aboriginal forms of structure are not
found in the animal organs.

§ 156.

The characteristic of the animal organs is rigidity and solidity. The
entire organ is throughout of one structure, and consists of one sub-
stance, which, indeed, still frequently is encircled and enveloped by
vegetable forms, as for example, the nerves by thin membranes, but
these constitute no essential component of the peculiar mass, but serve
only as its exterior case or covering.

If we examine the muscular system with this view we detect
solid fibres, which lie closely contiguous to each other, forming by
degrees larger bundles, that unite into an entire muscle. Even the
nicest microscopal investigation detects no cavity in the individual
fibres, but a solid uniform mass throughout. Each solitary fibre there-
fore is entire in itself, which, indeed, upon close examination, appears
divided by transverse partitions, and thus seems composed of cells,
but in fact it is not so. But we therein see the difference between the
vegetable and animal organs, the former growing into an individual
organ from the aggregation of consecutive vesicles or cells, and the
latter from the union of solid globules. The animal organs, therefore,
originate in the following manner ; it is not cells added to cells, but
globules, animal atoms, as some naturalists express themselves, to
globules ; a row of such globules form a solid fibre, several fibres the
bundle, and several of these a muscle or nervous cord.

THE ORGANS OF MOTION.

225

§ 157.

The nerves consist of filaments formed of consecutive globules, which
are enclosed by delicate membranes, the nervous sheath ( neurilemo ).
These globules are originally very loosely connected, and the nervous
filament then appears as a delicate tube, which encloses a finely granu-
lated pappy mass. The first commencement of the nerves is found thus
formed, as well in the embryo of the superior animals, as also in all
the inferior ones ; and whilst the latter constantly retain this original
grade of organisation, the nervous cord in the former works itself on
in the progress of development to a firm filament. Several of such
little filaments form the thicker nervous thread, and several of these
the nervous cord. Where suck threads or cords anastomose, meet,
or cross each other, the nervous mass distends and forms knots or
ganglions. That which we call the brain (cerebrum), which lies in
the head, is the largest and most perfect of these ganglia, and indeed
composed of various other smaller ones, and in its most perfect state of
organisation it is even furnished with internal cavities. It is there
first found where a head is first distinctly separated from the body. In
all animals without a head there is no brain, but their nerves originate
from a nervous ring encompassing the pharynx, which here represents
the central organ of the nervous system, whilst the brain, where it is
developed, gradually draws this ring to it.

THIRD CHAPTER.

OF THE ORGANS OF MOTION.

§ 158.

The organs of motion fall into two different sub-systems, namely,
the active or muscles, and the passive. The passive organs of
motion are, according to the different groups, subject to great changes,
and only in the higher grades of animal development do they become a

226

ANATOMY.

distinct system, namely, as bones, whereas beneath the grade of the
Vertebrata , they by degrees disappear, and only here and there, for
example, in the Sepia, the Echinus , and some of the Mollusca , viz. the
Terebratula, we observe more or less important precursory formations.
In general, in the Invertebrata , the exterior integument supplies the
place of the passive organs of motion, and this is especially the case in
the Articulata. In the Crustacea and Insecta , by their solidity in
the latter, and their quantity of calcareous matter in the former, they
imitate the structure of the true bones, and send off processes into the
cavities they form, which serve for the insertion of muscles, and in
every respect appear as a skeleton removed to the exterior. As such
we shall also consider and describe them. But it must nevertheless
not be overlooked, that the integument, as a continuation of the
intestinal canal, and, as it were, a re-fold of it, belongs properly to
the vegetative organs, and will in its structure present us with many
accordances with it.

I. Of the Hokny Skeleton.

§ 159.

The exterior of insects displays itself to us as a horny case, which is
sometimes firm and brittle, and sometimes soft and flexible, and in this
last consistence it takes the appearance of a leathery skin. This case
acquires its greatest consistency and strength in the beetles, especially
in their elytra, which wholly consist of it : we find it very soft and
thoroughly membranous in many of the Diptera , in most of the parasitic
insects, and in almost all larvae, particularly in the orders with an
imperfect metamorphosis. Also at first, when the developed head
quits the pupa case, the horny integument is in all equally soft, flexible,
thicker and more fleshy, and even colourless ; but after a few hours it
attains firmness, and gradually hardens in the course of a few days to
a rigid coat of mail, in which the insect is clothed. This change of the
integument takes place chiefly under the influence of the solar light;
the colours particularly are brought out by its impulse. For as plants
which grow in the dark take a pale or light yellow colour, insects also
retain this their original colour as long as they are withheld from the
effects of the light of the sun. Thence also is it that the majority of
larvae which live in the earth, or in dark shady places to which the
light of day cannot approach, are generally pale or colourless, and it is

THE HORNY SKELETON.

227

thence also that even perfect insects remain paler if they cannot,
immediately after quitting the pupa case, get into the light. From the
same cause t*he many pale yellow and particularly red-legged varieties
proceeds which we find in vast numbers of truly black or dark brown
insects. We must not, however, wholly attribute the darker colouring
solely to the effect of light ; the increase of the pigment during the
development contributes much to it ; indeed in some, namely, such
insects whose legs remain of a bright red whilst the remainder of their
body is entirely coloured, it may be caused by the original deficiency
of the pigment. The effect, nevertheless, of the solar light is incon-
testable, particularly in the colouring of larvae, for they are always
variegated, when from the very commencement of their life they have
been exposed to the influence of light, as is the case, for example, in
the caterpillars of the Lepidoptera. Also, from variegated or coloured
larvae, beautiful insects appear to proceed, whereas, from dull-coloured
ones, or pale or brown, and more or less uniform coloured ones, brown
or black insects. But the influence of climate is great upon colour,
and, as is the case in birds, we find the most beautiful and gayest
colours in tropical climates, whereas, the farther they recede from the
equator, the darker or blacker they become.

§ 160.

In structure, the horny case displays considerable conformity with
the skin in general, as it, like the latter, consists of three layers.

The exterior and finest layer, the epidermis, is smooth, shining, and
without any traces of texture. It admits of being pretty easily
separated from the coloured mucous rete lying beneath it, particularly
in recently developed insects which have been preserved in spirits of
wine, and is, in the majority of cases, colourless, sometimes, too, even
brown, and but rarely black, if the mucous layer be black. Uncoloured,
as it is in general, it is transparent and perforated all over with small
holes, through which hairs rise when the surface is hirsute.

Beneath this delicate epidermis we find the soft rete mucosum.
According to Straus it consists of two layers, of which the superior
smooth one is closely attached to the epidermis, and this alone appears
coloured. It is here we find the cause of the glittering, brilliant
colours with which many insects are so beautifully decorated. In the
butterflies and many others, namely, those with membranous wings,

228

ANATOMY.

it is brown or black, as also in all black insects. The variegated
colours of these do not therefore proceed from the rete mucosum, but
from the hairs clothing the surface. In spirits of wine it readily
dissolves, and thereby distinguishes itself from the second layer, which
is not affected by this fluid, and is uniformly black or brown *. This
second layer is always covered by the first, and participates no
otherwise in the colouring than by its darkness or depth adding to
the intensity of the colour above it. In bright yellow, red, or white-
coloured spots, it passes over naturally into this lighter colour.

The third and thickest layer of the general integument, the true
leathery tunic ( corium ), betrays itself by its want of colour and
peculiar structure. It consists, namely, of several layers of crossing
fibres, which form a light web, which, upon a careful investigation,
again admit of separating into several stratifications. Straus some-
times distinguished three, at others five, such strata. In the elytra of
beetles (for example, Dyticus, Hydrophilus) , there are delicate canals
between these layers, in which the formative juice seems to flow,
when the still small and short elytra of a just-developed beetle
distend themselves ; it is also in this leathery skin that the bulbs lie
which surround the roots of the hair. It is from this skin that the
roots of the hair derive their nutriment. A perforated point, many of
'which are displayed upon the surface of a multitude of insects, is a
partial deficiency of this leathery skin. The epidermis and mucous
rete consequently sink down, and thus a hollow is formed upon the
surface. At the same time, the sinking of the harder epidermis forms
a point to which the layers of the corium are attached ; thence is it
that the points stand generally in rows between two fibres of the
corium, for example, the three rows of punctures in the large water
beetles. ( Dyticus marginalise &c.)

§ 161.

We must consider the spines, hairs, and scales which cover the
surface of many insects, as portions of the integument, and, as it were,
partially separated parts. All three are like the horny substances of
the higher animals, for example, the claws and nails, not processes of

* According to Straus, p. 16. But if the brightly-coloured layer dissolves in spirits of
wine, how is it that so many insects, namely, the blue metallic or aeneous ones, retain
their colour in this fluid, and only some red or yellow ones lose it ?

THE HORNY SKELETON.

229

all three layers of the integument, but merely of the epidermis : they
are thickenings, and also often folds of this cuticle, between which a
coloured mucous has inserted itself. The corium is wholly wanting in
these excrescences. They are divided according to their form, and the
mode of their connection with the integument, into three different
groups.

1 . Spines differ from the following kinds by their wanting a true
root. They are therefore nothing else than pointed, spinous, conical or
hair-shaped processes, which rise from the surface, aild correspond
with it in colour and clothing. As a clear proof that they are mere
processes of the epidermis, or, when they appear more bossed (as in the
great horns of the Lamellicornia) , that they are true elevations of the
entire integument, is evinced by the circumstance that they produce a
hole in the horny substance exactly of their own dimensions when
broken off. These spines are not always simple, they are frequently
ramose, furcated, &c., as is observed in many of the caterpillars of
the butterflies.

2. Hairs are distinguished from spines in the first place by their
greater fineness and lesser compass, in combination with their pro-
portionately greater length, and again by the root by which they are
attached to the true skin. The hairs themselves are fine horny
cylinders, which frequently split and divide themselves like feathers,
and send off branches, thus acquiring a resemblance to the feathers of
birds. In general, they are largest in compass at their centre, and
become narrower towards both ends : the lower one is somewhat puffed
out, and has a small knob which sticks in the corium like a bulb in the
earth, and this is surrounded by a thin shell, exactly as is the case in
the large beard bristles of the mammalia.

3. The scales are properly flattened hairs : this is shown not only
by their gradual transition from linear to lanceolate and spatulate
forms, but also their exactly similar connection with the integument.
Each scale, namely, has a small pedicle, at the end of which the
knobby root is placed, and this with its sheath is inserted in the skin.
The scale itself is either round, pointed, forked, toothed like a saw
in front, and provided with longitudinal furrows upon its superficies.
Even this delicate and sometimes extremely fine membranous ex-
crescence consists of two layers of the epidermis, between which the
pigment has inserted itself. In the iridescent butterflies (Apatura
Iris , A. Ilia , Papilio Adonis, Mendaus , fyc.), the scales of the wings

230

ANATOMY.

play into a multitude of shades of colour, which proceeds, according to
Roesel*, from their peculiar structure. For whilst the surface of the
scales in the majority is flat, there are in these sharp parallel ridges
just as if small prisms were affixed to their surface. These prisms are
all upon one side of a metallic blue, and on the other side brown, and
thus according to the position of the butterfly or of the observer, either
the brown or blue side is seen f.

§ 162.

With respect to the chemical composition of the common integument,
it agrees in general with that of horn, but nevertheless distinguishes
itself by some peculiarities of proportion, which may probably arise
from its being formed, by not merely the epidermis alone, but by the
entire cutis.

All true horny substances consist essentially of azote (10. 2 —
12. 3), carbon (43. 0 — 53. 7)j> hydrogen (7* 3 — 2. 8), and oxygen
(29. 3 — 31. 2). In nitric acid it is dissolved, as also in a heated
solution of potass or natron ; muriatic acid, on the contrary, is coloured
only by degrees. Boiling water somewhat distends horn, but a
continued boiling in closed vessels (Papin’s digester) will nearly
entirely dissolve it. Dry distillation developes ammonia in com-
bination with carbonic acid, as well as other hydrocarbonates, and a
peculiar stinking oil, besides which other burnt matter remains
which is no further changeable.

The horny case of insects has as externally, a uniform consistency,
so also internally, the same constituents ; but it nevertheless dis-
tinguishes itself by the admixture of a peculiar substance, viz.
chitine or entomeilin, as well as by small portions of phosphate of
lime and magnesia. The peculiar character of chitine is its insolu-
bility in caustic potass. Exhibited separately, which is very easy by
means of treating horny parts in a solution of potass, it appears as an
almost colourless transparent substance, which becomes brown in nitric
acid, and in the dry distillation produces no carbonate of ammonia,
and therefore appears to contain no azote, and it burns in fire

* Insektenbelustigungen, yol. iii. p. 254. PI. XLIY. f. 5 — 8.

T This supposition of Roesel’s is erroneous ; the change of colour arises from the
reflection of the light, the same as in the buds of the Iris. The scales are merely
longitudinally striated. — Author's MS. Note.

THE HORNY SKELETON.

231

without previously melting, but it is soluble in boiling or heated
sulphuric acid.

Besides the above, small portions of albumen, a peculiar brown
colouring matter which dissolves in caustic potass, but not in boiling
alcohol, as well as traces of phosphate of iron, have been found in the
horny integument of insects, upon different analyses. The albumen
belongs doubtlessly to the third tunic, as does the brown colouring
matter to the mucous rete : to this also we attribute the chitine,
whereby the true horny skin, namely, the epidermis, will be found to
agree entirely with the horns of the higher animals *.

§ 163.

After this general inspection of the horny skeleton, we arrive at the
different parts of which it is composed. As we have already, in the
first section, in stating the orismological definitions of the insect body,
sufficiently exhibited its structure and explained its composition of
different pieces, we may here proceed more briefly, and merely add the
description of those parts which escape the observer upon an exterior
orismological examination. It will suffice then to repeat that the entire
body of the insect consists of head, thorax, abdomen, and the limbs,
namely, six feet and two or four wings.

The head exhibits itself as a single horny bladder with an anterior
and posterior aperture. The anterior one is closed by the cibarial
organs, and by the posterior one it stands in connection with that of
the thorax.

The thorax consists of three divisions. The first or prothorax
has two or four horny plates ; the dorsal plate ( pronotum ) ; the
breast plate {prosternum), and the shoulder plates ( omia ).

The second or mesothorax exhibits four, six, or seven plates. The
simple dorsal plate (mesonotum) ; the sometimes simple, sometimes
divided breast plate {mesosternum), and the two, also sometimes
simple, or likewise divided shoulder plates {scapulce). In many
orders {Diptera, Hymenoptera ), the three or six last are connate, and
form one ring.

The third or metathorax has, like the middle one, either two,

* Compare Aug. Odier Mem. sur la Composition Chemique des parties Corn^es des
Insectes, in M£m. de la Soc. d’ Hist. Natur, de Paris. Par. 1823. T. i. p. 29, Straus
Durckheim, p. 32, and Mr. Children in Zoological Journal, vol. i. 111 — 115.

232

ANATOMY.

four, six, or seven different plates. Above, in the centre, is the third
dorsal plate ( metanotum ) ; opposite to it on the breast, the simple
or divided third breast plate ( metasternum ) ; between the two, the
side plates ( pleurae ), and auxiliary side plates {par a pleurae),
sometimes separated, or either united together, or with the pectoral
plates.

This is the result of the investigations there instituted upon the
thorax : it now remains for us to inspect the cavities formed by these
plates, from the interior ; perhaps, also, from this point of view we
may discover some peculiarities.

§ 164.

INTERNAL SKELETON OF THE HEAD.

In the Hemiptera and Diptera, the head is a mere horny bladder
without any internal processes or bones for the insertion of muscles.
The same is the case in the head of the Lepidoptera, but the occipital
aperture is divided by a transverse bar into two holes, the under one
of which is the smallest, and admits only the nervous cord through it ;
through the upper one pass the pharynx, vessels, tracheae, and muscles.
These parts are not found in the Hymenoptera, but, on the contrary, a
broad ridge springing upwards from the lower margin of the occipital
aperture, which is prolonged towards the frons in two points, and
divides the upper portion of the head from the under. The Libellulce
among the Neuroptera exhibit the former division of the occipital
aperture into an upper and under one ; they have also several ledges
in the head, which spring from the anterior margins of the eyes, and
divide the large eyes from the brain, and this again from the frons.
In the Orthoptera , we again find the separation of the aperture into an
upper and under one. On each side, contiguous to that cavity, there
springs a process ; both unite in ap arch, forming a narrow cover,
which is attached in front to the frons by means of two other pro-
cesses. I call this cover the tentorium, because, as in the higher
animals, for example. Felis, beneath it lies the cerebellum of insects,
or the second ganglion of the nervous system, from which the
mandibular and labial nerves originate. Over it runs the pharynx,
and above it lies the first ganglion or the cerebrum. In the cavity of
the head of beetles we do not find the tentorium in the shape just
described, but as two high ledges originating from the throat and the

THE HORNY SKELETON.

233

lower margin of the occipital aperture, between which lies the cere-
bellum, and it is covered only by the pharynx. Sometimes ( Dyticus )
the pharynx rests upon a bar, connecting both ledges, and then the
cerebellum lies beneath it, and further forward, but the nervous cord
runs between the ledges. Contiguous to the occipital aperture two
small hooks spring from the ledge, which encompass the nervous cord,
and other longer fine branches of them project forwards towards the
front, which they do not reach, but bend upwards, and serve for the
insertion of small muscles, which retain the pharynx, running between
these branches. This frame-work is larger or smaller according to the
development of the cibarial apparatus, consequently most distinct in
the predaceous beetles with large oral organs.

§ 16*5.

INTERNAL SKELETON OF THE THORAX.

In the structure of the thorax, the Hemiptera, Ortkoptera, Neu -
roptera , and Coleopter a accord better together, from their prothorax
being more distinctly separated than in the other orders, in which the
entire thorax forms but one whole. This last structure is certainly the
most simple, and we will therefore commence with its inspection.

Upon paying some attention in the examination of the thorax of a
fly, bee, or butterfly, the important preponderance of the mesothorax
cannot escape immediate observation. The central dorsal plate oc-
cupies the entire dorsal surface, whereas the anterior one forms but a
ring (collar), and the posterior one also is not much more developed,
and, indeed, in flies and butterflies is entirely covered by the scutel-
lum, (compare PI. XIV. No. 1. f. 2. and No. 2. f. 2.).

The internal skeleton of this simple thorax is very unimportant in
the Diptera. Where we observe furrows on the exterior there are
internal ridges which correspond, and which surround the muscles
at their insertion, and separate them from each other. Audouin
calls those projecting ridges, which are also generally found where two
separate parts join together, Apodemes, Apodemata, and those to
which muscles are attached Apodemata insertionis. The largest of all
these ridges is Kirby and Spence’s Metaphragma, a thin, perga-
mentaceous partition, which, descending from the superior margin of
the metathorax, arches itself convexly outwards towards the abdomen,
and thus separates the entire cavity of the thorax from that of the

234

ANATOMY.

abdomen. Beneath this partition, namely, at the pectoral side, a lunate
space remains free, through which the internal organs pass from the
thorax into the abdomen Besides this most important position of the
internal skeleton of flies, we find, in the neighbourhood of where the
wings are attached, other horny arches, which serve for the insertion of
the alary muscles. In front also of the larger partition the scutellum
sends into the cavity of the thorax a small ridge, which is however as
unimportant as the other is important. The dorsal muscles ascend
obliquely through the thorax from the great partition to the meso-
notum, and thus hold the whole structure together.

In the Lepidoptera, which in the structure of their thorax have
most resemblance to the Diptera , the conformation is already some-
what more complicated. In this both agree that everywhere where
there are exterior furrows we find corresponding interior ridges which
separate the points of insertion of the muscles, and thus increase their
firm adhesion. Such a ridge rises from the centre of the mesonotum,
which passes to the scutellum, and there unites with the ridge that
separates the scutellum from the mesonotum. From the posterior
margin of the scutellum a broad partition (the mesophragma of Kirby
and Spence) descends, it bends first backwards and then forwards, and
thus forms a hook, to which the large dorsal muscles are attached. This
partition is analogous to the ridge of the scutellum in the Dipiera.
The third very narrow thoracic segment leans against it, forming also
a posterior partition, which, however, is much more delicate and fine
than the first ; consequently the relations of both the partitions, in
comparison with those described in the Diptera , are changed, here the
first is the largest, and there the second. The pectoral side of the
thorax exhibits a central projecting ridge as the line of separation
between the coxae and other smaller ones corresponding with the exterior
furrows.

The Hymenoptera make the direct passage from the forms already
described to those in which the prothorax is separated. The exterior
furrows of their thorax are true sutures, in which their parts are joined.
This has been already sufficiently explained above (§ 74 — 78.), and it
is there shown that the collare is the true prothorax of the Hymen -
optera ; we will therefore here proceed with the internal processes. In
the prothorax there are two strong pointed processes (PI. XII. No. I.
f. 4. a , a ), each of which has a double root ; one exterior one comes
from the margin of the prosternum, and an interior one from the

THE HORNY SKELETON.

235

central ridge of the same part ; between these roots the muscles of the
coxae pass, and between the processes themselves run the pharynx and
the nervous cord, and it is to these processes that the connecting
muscles of the pronotum and prosternum are attached. In the meso-
thorax we first find the prophragma (the same, 3. a), a small, not very
high, horny partition, which descends from the anterior margin of the
mesonotum, and we next find a delicate ridge which encompasses the
whole distinctly separated mesonotum. The mesosternum and scapulae
are closely joined in a half ring, and from the central carina of this ring
springs a broad strong ledge, which at its upper margin is furnished on
each side with a strong process (the same, 6. a, a ) ; they form with the
ledge a rectangular cross, and serve as points of insertion for the
muscles of the coxae of the middle legs, lying on each side contiguously
to the central ridge. In Cirnbex the cross is very distinct, in Scolia it
is merely a ridge, somewhat distended above. The metathorax of the
Hymenoptera is more complicated than in the Diptera and Lepidoptera,
because in them the abdomen is attached by only one small spot, namely,
by the circumference of the aperture beneath the metaphragma, conse-
quently there the metathorax encloses more powerful muscles than in
the preceding orders. The metaphragma is therefore exposed, and ap-
pears, for example, in Scolia , as an equilateral triangle above the arti-
culation with the abdomen, upon the very smooth apex of which the
abdomen turns (PI. XII. No. 2. f. 1). The apex itself is perforated,
and admits a strong band through it, which retains the abdomen (PI.
XII. No. 2. f. 3*). In front of this triangle is placed the very narrow
metanotum (the same, f. 1 and 2. f, f), and at its posterior margin a
triangular process runs inwards (the same, f. 4* and 5*), to which the
muscles retaining the abdomen are affixed. Between the metanotum
and metaphragma the two large side pieces and their auxiliaries lie,
separated from each other by furrows, from which internally strong
ridges spring, and to which the muscles of the posterior legs are attached.
In the saw-flies, which do not possess a petiolated abdomen, the pleurae
join together behind the metanotum (the same. No. 1. f. 1 and 2.
h, h), and the metaphragma lies internally as a narrow margin of the
metanotum, but the band is a semicircular tense membrane, which is
distended by the pleurae, and is very distinct in Cimbex.

Among the orders with a free prothorax the Hemiptera occupy the
lowest place. The entire prothorax is a single, above very broad,
beneath narrower ring, from the centre of the pectoral plate of which

236

ANATOMY.

two horny arches spring, which pass over the cavities of the coxae, and
attach themselves to the sides of the pronotum. These arches serve for
the insertion of the muscles of the coxae. Two other spinous processes
originate from the upper half of the ring yet more laterally, and bend
down to the beforementioned arch, proceeding gradually further from
the exterior case. In the very large mesothorax, anteriorly there is no
prophragma, whereas posteriorly, beneath the scutellum, a very large
mesophragma, which is longitudinally divided, the lower points of
' which unite with the arch, which, as in the prothorax, span themselves
over the cavity of the intermediate coxae. Other lateral ridges cor-
respond with exterior furrows. The metathorax is again very narrow ;
it has no metaphragma, and no arch spanning the cavities of the coxae,
the muscles of which are attached to the mesophragma. This descrip-
tion is sketched from Cicada fraxini, Latr. In the bugs, which pos-
sess a much smaller, at least flatter, thorax, I found (namely, in Penta-
ioma hcemorrhoidalis,) traces of the horny arch, and a distinct meta-
phragma, which likewise, like the mesophragma of the Cicada , is
divided, but at its centre diverges much more considerably, and is in
intimate connection with the pleurae.

The skeleton is much more perfect in the Orthoptera. Among them
the grasshoppers occupy the lowest place. In the prothorax, the
saddle-shaped pronotum of which encloses the entire part, we observe
two bent, flat, but high processes, which originate from the exterior
margin of the prosternum and rise to the pronotum. Two other pro-
cesses spring from the middle between the cavities of the coxae, and
form in removing from each other two arches, which span those cavities.
On the interior of each bow there is also frequently a smaller process*
which bends to its bpponent, and thus covers the nervous cord (PI. XI.
No. 2. f. 2. a, a). Both processes serve for the attachment of muscles,
and the larger bow for those of the coxae ; from the smaller ones two>
narrow muscles spring, which ascend to the back and affix themselves
to the margin of the dorsal piece. The same processes are found also
in the second and third thoracic segments, which likewise form small
arches, beneath which the nervous cord runs. Instead of the first
named exterior ones from each pleura a strong hook-shaped carina runs,
which separates the muscles of the legs and wings (the same, 6. b, b)~
The superior partitions, the meso- and metaphragma are small, and do
not lie vertically but obliquely, whence the cavity of the thorax acquires
much compas.s and wide avenues. The most perfect skeleton amongst

THE HORNY SKELETON.

237

the Orthoptera is found in the mole cricket ( Gryllotalpci vulgaris'). In
the prothorax (PL XI. No. 1. f. 1 — 3), which is formed of a very-
large, hard, bellied pronotum (a) and a very narrow, small, keel-shaped
prosternum (b), we observe a large horny partition (c), which de-
scends from the central line of the pronotum and spreads forward in
two furcating processes (e, e) ; to these processes two others attach
themselves, which originate from the upper margin of the aperture of
the neck, distend themselves in an arch downwards, and posteriorly,
and thus encounter the fork of the central ridge. And thence where
these processes join the furcate process the prosternum, which ante-
riorly is formed like a T, unites itself to them with its two branches,
and thus closes the anterior aperture of the prothorax. Posteriorly
two other processes originate from the central line (f, f), which de-
scend downwards, bend there towards each other, and join the posterior
extremity of the prosternum (*) ; at the same time each gives off a
hook which is directed upwards and backwards, and between these a
single horny bone lies (h), which stands in connection with them by
means of muscles (* *), and upon which the large pharynx rests.
Beneath this bone runs the nervous cord, encompassed by the posterior
shanks of the central ridge. The skeleton of the meso- and meta-
thorax is much smaller. Two processes descend from the scapulae
(PI. XI. No. 1. f. 4 and 8. d, d.) and unite together beneath, at the
central line of the mesosternum (the same, e). From the point of
union there arises a short dagger-shaped process (the same, 5), which
is barbed on each side at its base, and proceeds nearly to the end of the
metasternum . This point is, as it were, the true breast-bone, to which
the muscles are attached, and upon it the intestinal canal rests. From
the anterior margin of the metanotum the small mesophragma ori-
ginates, and which is perforated by a hole (the same, 7- &)> through
which the aorta passes, and besides there comes from the suture of the
metasternum and the pleura a clavate ridge, prolonged internally at its
anterior end into a pointed spine.

Some of the Neuroptera are very similar in structure to the grass-
hoppers, at least I found in the Ter mites just such horny arches upon
each of the three thoracic segments as covers for the nervous cord, and
horny ridges which separate the muscles from each other on the inner
surface of the pleurae.

The most perfect internal skeleton of all however is found in the

238

ANATOMY.

Coleoptera , although some portions of the thorax, namely, the pro-
thorax, do not form so complex a frame as in Gryllotalpa.

The prothorax consists in the majority of beetles of two separated
pieces, which, only in some capricorns ( Callichroma , Saperda ,) and all
the Rhynchophora, are connate *. In Carabus, Dyticus , Bupreslis
there lies between both two other free pieces, which I have called omia,
and which must be considered as the free lateral walls of the dorsal
plate. The moveable spines in Acrocinus longimanus (Kirby and
Spence’s Umbones ) are probably these same pieces, at least we can
give no other explanation of these otherwise perplexing organs. The
internal skeleton of the prothorax consists in a process originating
from the prosternum between the cavities of the coxae, which divides
itself into two when those cavities are distant from each other ( Oryctes ).
Above, this process has a tooth on each side, which bends towards the
side of the prothorax, and sometimes unites with it (in Hydrophilus ,
PL X. No. 3. f. 6 and 7* «)• It has frequently more or less the

appearance of a fork, or the letter Y, and Kirby and Spence thence
call it antefurca, a name which, notwithstanding its bad construction,
does not suit, because this process does not always furcate, and is
indeed wanting in many beetles, namely, in those with a simple
prothorax. In such cases a partition between the cavities of the coxae
occupies its place. I call it, when present and of importance, the
processus internus prosterni. The nervous cord passes between its
branches.

In the mesothorax the partition or prophragma descends from the
anterior margin of the mesonotum, and is directed somewhat forward.
It is in general but very short, and rather a small ridge, to which the
connecting muscles of the meso- and metathorax are attached. We
again find the internal process upon the mesosternum, but here it ori-
ginates with more widely divided shanks, each of which shanks forms
an arch, which, as in Cicada , spans the aperture of the cavities of the
coxae, and ascends as high as the suture of the scapulae, to unite itself
with the surrounding margin of that part. In the Lamellicornia this
arch does not reach the suture, but projects freely into the cavity, serv-
ing as a point of attachment for the muscles. In this shape the entire

* Meckel erroneously says this of all. See his Vergleich. Anatomie, vol. ii. Part i.
p. 76.

THE HORNY SKELETON.

239

process is called by Kirby and Spence the medifurca ; I call it, to cor-
respond with the first, the processus internus mesosterni, or arcus ster-
nales inter ni.

The metathorax has the most developed skeleton, and is in ge-
neral in the beetles the largest of the thoracic segments, whereas it
was the central one in the flies, butterflies, Hymenoptera, and Cicada.
We observe, at the metanotum, the meso- and metaphragma, two parti-
tions descending perpendicularly from the anterior and posterior limits
of this plate ; they are not very high, but to them the large dorsal
muscles are attached. In apterous genera ( Carabus ) the entire meta-
notum, and with it both partitions are very small. We find, besides
these two partitions, no other elevated process at the metanotum,
whereas there is a very large one at the metasternum. This originates
as a thin, frequently merely pergamentaceous, triangular partition from
its central line, and projects freely into the cavity of the thorax, but
with its apex more directed towards the abdomen. The thither directed
edge of the triangle is thicker, like a ridge ; it is placed upon its pos-
terior margin, and originates from the spot where both the cavities of
the posterior coxae are united. When this ridge reaches the upper
point of the triangle it sends off on each side a strong process, which
together form a direct cross with the ridge itself. A third process,
which is, as it were, the continuation of this ridge, originates between
both, and runs in a direct line parallel with the carina of the sternum
as far as the mesothoracic segment, gradually decreasing to a point.
This central process is excavated above, and thus forms a small channel,
in which the intestinal canal rests. In Dyticus it even furcates, and
with both prongs of the fork it encloses the intestine, and low^er down
the nervous cord. In Oryctes , however, all three processes, the two
transverse ones and the central one, equal both in form and size,
thus construct a three-rayed star 5 in Hydrophilus the central process
is wanting, as well as in Carabus and Callichroma , where the whole
frame is much smaller, and is placed between the cavities of the coxae,
whereas in others, at least in Dyticus and Oryctes, it projects as far as
the base of the abdomen. To this skeleton numerous muscles are
attached ; posteriorly the muscles of the coxae ; at its lateral points
delicate muscles, which rise to the limits of the back ; to its anterior
points likewise two delicate muscles, which pass through the cavities
of the meso- and prothorax, and affix themselves to the horny plates
of the membrane of the neck (see § 167. 4). Besides this large pro-

240

ANATOMY.

cess, which Kirby and Spence call the postfurca, Audouin, on the con-
trary, styles it, in connection with the preceding ones of the pro- and
mesothorax, the entothorax *, we find but a few other ridges produced
by the sutural connection of the pleurae with the sternum ; these are
Audouin’ s apodemata, which vary in their course according to the
varying forms of the parts, and are of much less importance.

§ 166.

INTERNAL SKELETON OP THE ABDOMEN.

The abdomen has no internal skeleton, but consists of horny rings
connected together by a flexible membrane, and each of which is divided
into a dorsal and a ventral plate. In the grasshoppers, at least Gryllus
and Locusta , horny half circles arise from the lateral edges of each
dorsal plate, which are about one-third of its width, and extend as
high as the dorsal depression. It is to these arches that the long air
bags are attached, which form a zigzag, and which we have fully
described above. Marcel de Serres f , who first discovered and de-
scribed them, called them ribs, a comparison which in so far is not
inappropriate, from their encompassing and protecting the air bags of
these creatures. But they are properly elastic processes, which are in
a directly opposite action to that of the oval air bags, which they dis-
tend by springing back, when the contraction of the spiral fibre has
shortened them, and has thereby removed the process to which the bag
is attached from the abdominal plate. They consequently belong to
the respiratory system, and were considered under it by their first
discoverer.

§ 167-

SKELETON OF THE LIMBS — MODE OF ARTICULATION.

The skeleton of the limbs is merely external, and as such it has been
sufficiently described above (§ 79) in a preceding division ; we have
also there indicated the way in which the different parts of a limb are
connected together, it therefore remains merely necessary here to give
a special description of all the different kinds of articulation both of
the limbs as well as the other portions of the skeleton.

I. Connection without motion ( synarthrosis ). — This kind of

* See Meckel’s Deutsche Archiv., &c. tom. vii. p. 440.
f Mem. cle Mus^e, tom. iv. (1819).

THE HORNY SKELETON.

241

connexion of the parts of the skeleton we find chiefly in the thorax, in
the sutures by which the several plates are united together. We may
distinguish two descriptions of it: —

1. The suture is the connexion of two plates of the skeleton by
insertion, a projecting ridge of the one corresponding with a channel in
the other, and the connexion is thus made without the intervention of
membranes. This mode of connexion is found between the several
plates of the thorax. Where both join they bend inwards, and thus
form an even suture. All sutures in insects are therefore simple,
smooth, without teeth, or interchanging processes.

2. Symphysis is a connexion upon the whole resembling a suture,
but which is produced chiefly by the intervention of a soft membrane.
This admits of a slight separation of the connected parts, which is
increased in proportion to the elasticity of that membrane. It is by
means of this that the posterior wing of the scapula is connected
with the parapleura. This sort of connexion, thus admitting some
degree of separation, was the more necessary here, as the second spiracle
of the thorax lies between the two plates, and therefore a firm union
would have prevented a free respiration.

A mere variation of this form, which, however, admits of a greater
motion of the connected parts, is called by Straus a scaly joint
( articulation ecailleuse). It is distinguished chiefly by the lip of the
one plate passing over the connecting membrane, and thus covering
the lip of the other plate like a scale. This mode of articulation is
found in the plates of the abdomen, in which each successive plate
is covered by that preceding it. The mobility of parts thus con-
nected is but passive, whereby an extension of the body on all
sides, but chiefly longitudinally, is made possible, for example, when
its contents swell, as is frequently the case in the female after im-
pregnation.

II. Connexion with motion ( Viarthrosis ). — All connexions
classed under this head are generally called joints. They are found
chiefly in the limbs, in the connexion of their several parts. In
insects we distinguish the following different forms of articulation : —

1. The flap joint (syndesis) * When two parts meet at a suture,
and are connected together by membranes at the inner side, but so
that they may move in the suture to and from each other. This mode
of articulation is found, for example, in the under lip, where the
mentum joins the gula.

242

ANATOMY.

2. Gynglimus. — When two parts are so connected that the one
is inserted within the other at its origin, and stands in intimate
connexion with it only at two opposite points. The part turns
upon these two points as upon its axis. This therefore admits of
but one kind of motion, viz. that of its approaching to or receding
from the other part. It is thus that the coxae and trochanter,
femora and tibia are connected, and the mandible with the head. A
more detailed description will more clearly explain the peculiarity
of this articulation. Upon examining the upper extremity of the
tibia, which has been removed out of its socket, we shall observe
upon the exterior as well as interior a precise semicircular furrow,
behind it a concentrical but smaller ridge, and beyond this a cir-
cular fossulet. The inner surface of the femora displays on each
side a ridge accurately corresponding with the furrow, beyond this
a furrow corresponding with the preceding ridge, and in the centre
a minute elevation, from which a small but very firm band passes
into the central fossulet of the tibia. This band appears to pierce
transversely through the hole in the tibia, and passing through the
opposite side to be affixed to the corresponding central elevation of
the femora. Thus, therefore, a very firm connexion and a secure
joint is produced. The articulation of the mandible is very similar,
but which is distinguished from it by the upper side of the mandible
having a semicircular ridge, and upon its under side merely a spherical
ball joint.

3. Rotation ( rotatio ). — Is that kind of articulation when a cylin-
drical, ovate, or conical part is sunk into a cavity adapted to its
convexity. Both the inserted body and the cavity are drilled at one
spot, and are united around the aperture by means of a membrane :
besides which there are balls at both poles of the axis of rotation
adapted to corresponding sockets of the other part ; wbereby a rota-
tion of the encompassed part upon its axis is made possible within
the corresponding cavity. This mode of articulation is found in the
coxae of the Coleoptera , Hymenoptera , Hemiptera , or more or less
evident in the hip-joints of all insects.

4. A pree articulation ( arthrodia ). — Is when a conical part
is inserted in a corresponding cavity, both being pierced at one spot,
and united by membranes around the circumference of the cavity. This
mode of union, which is the most common of all, admits of the freest
motion upon all sides ; and, indeed, what is still more, the exsertion

THE HORNY SKELETON.

243

of the ball out of the socket, as far as the membrane admits of
extension. We find thus united the joints of the antennae, palpi, and
tarsi, the head with the thorax, and the prothorax with the mesothorax,
in those insects which have a moveable prothorax. At the neck, or the
connecting membrane of the head with the thorax, we find, besides, in
the Coleopter a, two bean-shaped horny plates ( pieces jugulaires of
Straus), upon which the occiput moves. These plates, which might
be called throat plates ( jugularia ), lie transversely in the posterior
portion of the membrane which spans the large aperture of the
prothorax like a drum-head, and serve for the insertion of several
small thin muscles, and, among others, to the two which originate
from the central point of the internal metathoracic process which
passes through the cavity of the thorax. Their true function is
doubtlessly to retain the membrane of the neck distended, and to offer
to the occiput a smooth surface, upon which it may turn with facility.
In black or dark beetles it is of the colour of the exterior integument
(Hydropliiius piceus, Oryctes nasicornis ), and is therefore very per-
ceptible when the head has been removed from its articulating
cavity. In Dyticus I likewise found similar plates between the meso-
and meta-notum. A small horny piece, similar in function, lies also in
the membrane between the coxae and the sternum in the four anterior
legs. It is properly a process of the joint become free, and which, in
the intermediate legs, in which the motion is less, stands in closer
connection with the coxae. Audouin calls it trochantinus. I have
been able to find this piece only in Dyticus ; it exists also in
Melolontha> according to Straus, who calls it rotule.

§ 168.

STRUCTURE OF THE WINGS.

We have already, in a preceding division, sufficiently described the
formal differences of the wings and elytra, as well as of the legs,
to complete which we have but to give here a detailed explanation of
their peculiar structure. In the description above, we have already
mentioned that they are bags formed of a simple membrane, in which
horny ribs are distributed. This simple membrane is nothing else
than the epidermis, which, proceeding from both sides of the thorax,
forms the wings. This is most distinctly seen in those wings which
have a broad base, as in the Coleoptera, Ortkoptera , &e., in which we

r 2

244

ANATOMY.

even observe at the base a much greater thickness of the wing, which
is caused by the two layers of the epidermis not having closely joined
together. Upon the margin of the wing the two layers pass into each
other, and thus the bag is formed. This bag admits of being distinctly
represented as such, if just-developed insects be placed in spirits of
wine ; the fluid then passes between the still fresh and soft membranes
of the wing, and filling their internal space, distends them like a bag.
Heusinger* observed this in fresh specimens of butterflies, and I have
myself detected it in a young individual of Anthophagus plagiatus,
Grav.

Howsoever smooth, fine, and transparent the membrane of the
wing appears to the naked eye, an investigation with the microscope
reverses this, and exhibits it as covered with innumerable small hairs,
which rise from bulbous roots upon the wing, and densely cover its
whole surface. In some insects, for example, the common gnat, they
are longer, broader, and lanceolate, and pass over into the scales of
butterflies, which are absolutely nothing else than transformations of
the hair peculiar to almost all insects.

The ribs of the wings are hollow, horny tubes^ by which the two
plates of the wings are supported. Their situation and reciprocal
relation, as well as the cells formed by their connection, we have
become acquainted with above: we will merely add here, that each
rib is filled internally with a soft parenchyma, in which I have
detected a vessel very large in compass, and by the side of it a fine
nerve. The vessel appeared to come from the cavity of the thorax,
and the nerve entered from the same part, coming probably direct
from the approximate ganglion ; therefore, close to the posterior wings
in beetles, upon which I made the observation, and from the third
ganglion of the thorax. In the vessel itself I could detect no structure,
and, least of all, the spiral fibre observable in the tracheae, even upon
an enlargement of three hundred times f. I thence conclude that it is
a blood-vessel, which is supported by Cams' observation of the motion
of a fluid in the ribs of Lampyris . How else could the wings be
distended, were not the liquid flowing into these vessels the cause of
it ? But it is not necessary that we should thence conclude upon a

* System der Hystologie, 2 Heft.

f I have since detected the spiral fibre in these vessels, and observed that they are
genuine tracheae. — Author's MS. Note.

THE WINGS.

245

connection of these vessels with the heart, it being well known that
blood is found in the entire cavity of the body of insects, and, by each
contraction, can be injected into the open ribs of the wings. Chabrier*
describes, besides, a bag in the posterior wings of beetles, which lies at
their point of flexure, and which is filled with a fluid during flight.
The equilibrium is thereby thus supported. He considers in the other
orders the stigma analogous in function to this bag. The clammy
fluid contained in this stigma is probably merely parenchyma, but even
in insects which had been immersed in spirits of wine, I have found a
moisture in the bag, but which, without doubt, was introduced from
without.

The connection of the wings with the thorax varies according to the
different orders. Broad wings, attached by their entire bases, are found
in the Coleoptera, Orthoptera , Dictyoptera, Neuropier a, Hemiptera,
and Lepidoptera , consequently in the majority ; wings with pedicles,
and attached to the thorax by a narrow base, are found in the
Hymenoptera , some of the Neuroptera, and the Diptera.

The superior wings, or elytra, of the beetles have at their base two
short processes, the one of which originates at the inner margin, and
the other at the outer margin. Both articulate with two processes at
the mesonotum, which originate from it at the anterior part of the
lateral margin, and are united to those of the elytra by means of a
flexible membrane. In this membrane several free horny pieces are
placed, to which the muscles are attached which move the wings.
Straus found in Melolonlha four such plates, and called them shoulder
pieces (1 .pre-epauliere, and 3 . epaulieres) . From the posterior margin
of the internal process of the joint of the superior wing, a delicate
semicircular membrane springs ( frenuvn of Kirby and Spence), which
passes over to the similar process upon the mesonotum, and which
retains the expanded wing. In Dyticus it is narrower, fringed upon its
margin, very broad in Hydrophilus , and in apterous beetles ( Carabus )
it is wanting. This membrane, which is present in the majority of
insects, and which, for example, in Libellula, is the coloured triangle
at the posterior margin of the wing, and appears very similarly in the
wings of the grasshopper, is so far of importance, that from it the
scale behind the wings of the Diptera derive their significance. They
are, namely, the frena of the superior wings, which cannot longer

Sar le Yol ties Inscctes. Mem. du Musdc, tom. vi. — \iii.

246

ANATOMY.

remain in immediate connection with the base of the wings, from
this being contracted and narrowed, whereby the scale is separated
from the wing. We nevertheless still find in many Diptera a con-
nection. It is remarkable, and confirmatory of this opinion, that those
Diptera which want this scale, are such whose wings stand off in a
state of repose, as, for example, in Tipula. But this frenum passes
always from the superior wing to the lateral margin of the scutellum,
and the scale of the Diptera is always found in this situation. The
Lepidoptera are not deficient in this membrane; in the Hemiptera
(for example. Cicada, Plate XIII. No. 5. 1.), it is partially horny ;
in the Hymenoptera it has but small compass, but in these it is not
either ever wanting.

The connexion of the posterior wings is still more intimate than
that of the anterior pair, whenever they are larger than the latter.
The Coleopter a exhibit towards the base of the wing several plates,
which lie free in the membrane, and which, like those of the elytra, pro-
mote and support their motion. Straus distinguishes five in Melolontha,
and calls them axillary pieces (1. prcaxillaire, and 4. axillaires').
Neither is the connecting membrane which runs from the last portion
of the joint to the margin of the metathorax wanting here. This is
likewise the case in the large posterior wings of the Orthoptera as
well as of the Dictyotoptera and Neuroptera, in which the plates and
membrane are also found, and in the latter frequently very much de-
veloped. Nor is it wanting in the other orders.

The Diptera are remarkable from having no posterior wings, but
instead of them they are provided with two pediculated knobs, which
are called halteres. Latreille and other French naturalists will not
allow these organs to be considered as the rudiments of the posterior
wings, whereas the majority of the earlier entomologists, and many
modern ones, particularly the Germans, consider them as such. If we
look to the situation of these organs, it speaks incontestibly in favour
of this opinion, for they are exactly situated where the posterior wings
of other insects are found. Besides, they stand in the same connection
with the metathorax; and, indeed, in the larger flies, for example,
Tabanus bovinus, we detect the analogue of the connecting membrane.
The knob is also sometimes (Tipula gigantea, lutescens) broad, flat,
and provided with ribs like the wings, these are all facts which cannot
be disputed, and which corroborate the correctness of this opinion.
Latreille’s decision, therefore, that the last segment of the thorax in

THE MUSCULAR SYSTEM.

247

the Diptera belongs to the abdomen, because a spiracle is found upon
it, requires no refutation after the description given above of the
general situation of the spiracles.

We must still make an observation upon the connection of the wings
together. I know but of two of all the orders of insects which exhibit an
apparatus for the connection of both the wings together, these are the
Hymenoptera and the Lepidoptera.

In the Hymenoptera it consists of a row of minute hooklets, which
are bent backwards, and are placed upon the anterior margin of the
posterior wing, and which fit to a small groove along the posterior
margin of the superior wing.

In the Lepidoptera this apparatus is somewhat more complicated.
Giorna, who appropriates to himself the priority of this discovery,
although it was made thirty-seven years before him by De Geer *,
has, however, given the most detailed account of it f. There is found,
namely, at the base of the posterior wings of many of the crepuscular
and night moths, a spine projecting from the anterior marginal rib,
which is sometimes divided into several radiating branches. This spine
is enclosed by a hook placed upon the central main rib of the superior
wing, which surrounds the whole circumference of the spine, which passes
through it as through the eye of the needle, but which can freely move
itself to and fro within it. If the superior wing expands by means of
the spine, it draws the inferior wing with it, and both remain in
immediate connexion; a provision of nature which is rendered the more
necessary, as we shall see below, from the mesothorax being furnished
with large muscles of connexion and motion, which are entirely wanting
in the metathorax, so that the muscles which distend the superior
wings must act likewise upon the inferior ones. We find a similar
adaptation in the muscles of the Hymenoptera.

II. The Muscular System.

§ 169.

The muscles of insects, like those of the higher animals, consist of
two parts, viz. the tendon and the muscle. Under the name tendon
we understand the in general more compact, firmer, and uncontractile

* M£m. pour servir ä l’Hist. des Insectes, t. i. p. 173.
-|* Trans, of Linnaean Society, vol. i. No. 7. Load. 1791.

248

ANATOMY.

ends of the muscles, by which they are attached to the parts to be
moved : the muscle itself is the contractile fleshy portion lying between
these tendons. If the tendon be wanting, the entire generally very
broad end of the muscle is affixed to the horny skeleton, and such
muscles appear applied more to the strengthening of all the parts than
to the motion of individual ones.

The tendons vary much in shape according to the structure of the
muscle, but they always consist of a horny mass, distinguished from
that of the skeleton by its wanting the epidermis, and the coloured
layer of the mucous tunic, and therefore Straus considers them as an
elongation of the internal layer of the horny skeleton, to which the
epidermis cannot assist, as it lies externally, and this view appears
to be correct. The horny tendons, consequently, cannot participate
in the external colour of the exterior integument, but they are, like its
internal layer, of one uniform black or brown hue, so that they are easily
distinguished from the flesh of the muscle. In form they are longer or
shorter bones, which, at the side turned to the muscle, gradually
distend into a flat surface, to which the muscle is attached. The form
of these surfaces varies according to what is required by the muscle, for
it is broad and plate-shaped for short thick ones, and for long thin ones
we find it also long and resembling a scale.

The muscle itself is a union of delicate white, or yellow and red
parallel fibres, which frequently, particularly if the insect has been
preserved in spirits of wine, are readily separated from each other.
If these fibres be examined under the microscope, we distinguish
partitions at short distances, which appear to separate it in equal parts;
but upon a careful examination, we find that the fibre consists of small
laminae lying one upon the other, and which at one spot are de-
pressed into an angle, and are thereby attached to each other, which
consolidates their union. This discovery, for which we are indebted
to the careful Straus*, is the more important, as thereby we detect a
uniformity of structure of the animal organs in their most minute parts,
as the fibres of the nerves likewise consist of consecutive globules. In
the muscular fibres these globules have become plates from their firmer
connexion together, and their consequent mutual pressure. Straus
found this union in all the muscles, but in the larger ones the indi-
vidual fibres first formed bundles, whereas, in the smaller ones, they lie

Consitl. General, p. 143,

THE MUSCULAR SYSTEM,

249

regularly together. In the Mammalia (the ox) he did not find this
structure, whereas he saw it in the eagle, a fact, which, if shown to be
the case in all birds, would still increase the evident parallelism of both
classes*.

With respect to the general form of the muscles, we may in the
first place separate those without tendons from those with. Those
unprovided with tendons have the peculiarity of retaining throughout
their whole course parallel sides, and always take the form of flat bands
or thick prisms. Such flat band-shaped muscles we find between the
several segments of the abdomen, and which serve to unite them
together : the prismatic muscles without tendons we find between the
phragmata, and indeed the dorsal ones in general are of this form.

The muscles with tendons, Straus arranges under the following five
divisions : —

1. Conical muscles. The belly of the muscle has the form of a
cone, originating from a broad flat base, and proceeding to a smaller
point of insertion. From the apex of the cone the long tendon
springs, and distends itself in the belly of the muscle, in the direction
of its axis, here spreading into a flat surface, to which the individual
fasciculi are attached. Sometimes this surface is divided into several
lobes.

2. Pyramidal muscles. The belly of the muscle is shorter, as is
likewise the entire tendon surrounded by it. This is broad and divided
into several leaves (for example, the mandibulary muscles).

3. Pseudo -penniform muscles. Flat triangular muscles, the
fibres of which originate all in a row, and attach themselves sometimes
at one, and sometimes upon both sides of the long tendon (the muscles
of the femorse in Locusia ).

4. Penniform muscles differ, from the margin of their tendon
being fibrous. These fibres originate sometimes at one side and some-
times at both sides of the long tendon.

5. Compound muscles are those which consist of simple bellies,
all the tendons of which unite into one band, or in which one tendon
after the other takes up several bundles of muscles.

To these five forms we may add, as a sixth, cylindrical muscles,
the tendon of which is a flat round plate, to which the fibres are

* Compare Nitzsch in Meckel’s Archiv. 1826.

250

ANATOMY.

attached. From the centre of this plate a longer or shorter straight
process springs, which unites itself with the part requiring motion.
The great muscles of the wings are formed in this manner. Audouin
considers these horny tendons as processes of the thorax, and he calls
them Epidemes.

Double-bellied muscles, or such, namely, where two bellies lie behind
each other, and are united together by a central tendon, as they are
found in the superior animals, are not discoverable in insects.

Besides this division of the muscles, according to their variations of
form, we may likewise separate them into three groups, according to
their functions.

The first, which we will call connecting muscles, pass within the
cavity of a part from one portion of the skeleton to the other, and thus
consolidate the connexion of the several plates together. These are in
general the largest of all the muscles, and they have no tendons : when
they contract, the cavity in which they are found contracts likewise,
but when they become flaccid, it again distends. To these belong the
large muscles of the back, which are spread between the phragmata,
and likewise the large muscles of the sides, which pass from the back
to the breast, and then those which lie between the plates of the
abdomen.

The others, which may be called distinctively the muscles of motion,
pass from a portion of the horny skeleton to the limbs, or from one
joint of the latter to the other. They originate with a broad base from
a part of the skeleton, and pass on by a thinner apex, terminating in a
tendon, to a part of the limb. Their character also divides them into
two groups. The first, which are called flexors (adductor es seu
flexores ), lie on the inside of the limb, and draw it to its base, to
which it is affixed ; the others, or extensors ( abductor es seu
extensores), work in an opposite direction, distending the limb again
as soon as they get in action. They lie on the exterior of the limb,
and attach themselves to the exterior angle or edge of the parts to be
moved.

These are the various general qualities of the muscles ; we come now
to the investigation of the individual ones, which we will examine in
the order of their situation, examining first the muscles of the head
and its joints, then those of the thorax and the limbs attached to it, and
lastly those of the abdomen.

THE MUSCULAR SYSTEM.

251

A. Muscles of the Head.

§ 170.

The muscles of the head may be divided into those appropriated to
the motion of the whole head and the muscles of the oral organs and
antennae. The head has the freest motion of all the moveable parts of
the body ; it has thence the most numerous muscles of motion, namely,
such which raise it (extensors), such which sink it (flexors), and such
which turn it to the right and left (the rotatory muscles).

The extensors, or raisers of the head {elevator es capitis ), are two-
fold ; two bellies originate close together from the central line of the
pronotum, they somewhat separate in their course, and attach themselves
laterally to the margin of the occipital aperture (thence called external
extensors, elevator externi). They are shorter and broader than the
two other bellies, which come from the prophragma, proceed con-
tiguously over the pharynx and through the prothorax, and passing
between the preceding affix themselves to the central part of the
superior margin of the occipital aperture. All four raise the head up,
one acting alone draws it somewhat on one side.

The flexors, or depressors ( depressores capitis ), are two small
muscles which lie at the under side of the neck, and originate from
the neck-plate, or, where this is wanting, from the inner margin of the
prosternum, and affix themselves to the lower margin of the occipital
aperture.

Contiguously to them two other small muscles originate, which turn
outwardly and attach themselves to the lower part of the lateral margin
of the occipital aperture ; they correspond with the anterior bellies of
the extensors, and might consequently be called external flexors
( depressores externi).

The rotatory muscles of the head ( rotatores capitis ), are two broad
flat muscles, which, coming from the lateral margin of the prosternum,
affix themselves to the corresponding margin of the occipital aperture,
and bend the head outwardly if one only be in action, but in conjunc-
tion they assist to draw the head into the cavity of the thorax.

In all insects with a free head, {Dip ter a, Lepidoptera , Neuroptera ,
Dictyotoptera, and Hymenoptera,) all these muscles are very small,
flat, and like a band ; the following, on the contrary, which belong to
the plates of the throat, are, as well as these plates, entirely wanting.

252

ANATOMY.

The muscles which run to the plates of the throat may properly
be classed with the flexors of the head, for, as the true flexors
are attached to these plates, a contraction of these plates likewise
draws the head downwards and backwards. There are three on
each side : —

One, the flexor of the throat-plate, originates from the inner
process of the prosternum, and affixes itself in the centre of the plate
of the throat.

The second, or straight extensor, affixes itself internally, contiguously
to the other, and passes diagonally from the prophragma through the
cavity of the prothorax.

The third, or oblique extensor, comes from the exterior margin of
the pronotum, and affixes itself to the plate of the throat, between the
former and the flexors of the head. The two last retain the plates
of the throat in their place, which naturally, from the situation of the
flexors of the head, is exposed to greater force ; the first assists
the head inwards, and also to draw the plate of the throat down,
acting in opposition to the two extensors.

§ 171.

MUSCLES OF THE MANDIBLES.

Of the muscles of the joints of the head we will first examine those
of the mandibles; we find two, namely, a flexor and an extensor.

The flexor of the mandible originates from the entire posterior and
upper side of the skull ; it becomes pyramidal and affixes itself, after
passing the lateral portion of the brain, by means of a strong and fre-
quently divided tendon to the inner margin of the mandible. In many
insects, for example, the grasshopper, the entire muscle consists of two
contiguous bellies.

The extensor of the mandible originates beneath the former from
the posterior and lower portion of the skull ; it is smaller and weaker,
it has a long thin tendon, and affixes itself to the exterior margin of
the mandible between the two above- described joint balls.

The maxillae, which are of a much more complicated structure, have
several motive muscles, which may be divided into four groups,
according to the part of the maxillae to which they pass.

There are three muscles which move the entire maxillae.

The first, the flexor of the maxillae, is the largest ; it originates
from the inner side of the throat, closely in front of the occipital aperture.

THE MUSCULAR SYSTEM.

253

and is sometimes conical, and affixes itself to the innermost process of
the transverse basal portion { p . basilar is s. cardo ).

The extensor of the maxillae originates from the inner side of each
temple, beneath the eyes; it is the smallest of the three, and affixes
itself to the most external process of the base.

The third muscle, which may be called the first contractor of the
maxillae, originates from the lower margin of the occipital aperture,
passes transversely over the flexor, and inserts itself between the flexor
and extensor at the base. Both contractors acting in conjunction
draw the maxillse together.

Two other muscles, which likewise move the entire maxillse, are
inserted in the piece described as the stem.

The one, which may be called the second contractor, originates like-
wise from the margin of the occipital aperture, but in the centre, in
front of the first, and inserts itself in the lowest most internal angle of
the base; the other, or second flexor, originates from the inner wall of
the occiput, lies above all the others, and inserts itself with a long thin
tendon, likewise at the lower inner angle of the stem, closely conti-
guous to the second contractor. It is the longest and largest of all the
muscles of the maxillse.

The galese, which are, as they have been called, the internal
maxillary palpi, receive each two muscles, which lie in the maxillae
themselves.

The flexor of the galea is the largest ; it originates from the inner
side of the stem, and affixes itself to the inner margin of the galea.

The extensor of the galea, which is longer but smaller, originates
from the inner side of the exterior wall of the stem, and inserts itself
at the exterior margin of the galea. The exterior one gives off also
numerous fasciculi to that portion of the maxillse which bears the palpi,
and it is thereby united intimately with the stem.

The last muscles of the maxillae, which, like the preceding, lie
wholly in it, move the maxillary palpi. Their flexor originates from
the inner margin of the palpal plate belonging to the maxillse, and
inserts itself at the inner margin of the first joint of the palpus ; their
extensor comes from the inner side of the exterior wall of the stem,
and inserts itself at the exterior margin of the first joint of the palpus.

The joints of the palpi themselves have each two muscles, a flexor
and an extensor. The former springs from the inner margin of the

254

ANATOMY.

preceding joint, the latter from the exterior, and both insert them-
selves at the corresponding parts of the basal aperture of the joint which
they move.

§ 172.

MUSCLES OF THE LIPS.

The upper lip, or labrum, has in Melolontha but one kind of muscle,
namely, the flexor or bender, which originates on each side from the
brow, close to the eyes, and runs down to the extreme angle of the
labrum. In Locusta, I have distinctly observed two different muscles ;
both were flat, resembling bands, and originated from the forehead,
the anterior one, or abductor of the labrum, originated between the
eyes, and inserted itself upon the inner surface of the exterior wall of
the labrum ; the second, or adductor of the labrum, originated above
the former, at the boundary between the forehead and vertex, and ran
separated from it as far as the apex of the labrum, leaning against the
membrane of the soft palate, and supporting it.

The labium, like the maxillae, being of a more complicated struc-
ture, receives several muscles.

The adductor of the labium originates from the most anterior edge
of the skeleton of the head ; it has a broad basis, and runs pyramidally
to the mentum, joining it in front of the articulation of the palpi. In
the Coleoptera there are two adductors, one on each side of the men-
tum ; in Locusta I found but one central one.

In front of it, or between them when there are two adductors to the
labium, the muscles of the tongue originate, which are two, likewise
short, pyramidal muscles inserted at the lower side of the tongue, and
connect this with the labium : I call them the reins of the tongue. In
Locusta I found but one muscle of the tongue, resembling that of the
labium in its broad flat form, which originated in front of the latter,
from the tentorium, and passed to the posterior wall of the tongue.
To the anterior wall, or the soft membrane clothing the tongue, on the
contrary, another muscle passed, which I call the flexor of the tongue,
and which, running likewise closely to the membrane of the tongue
and of the palate, originated with a broad base from the anterior
boundary of the tentorium.

The first joint of the labial palpus has its flexor and extensor ; the

THE MUSCULAR SYSTEM.

255

former originates from the centre of the mentum, and passes to its
inner margin, and inserts itself at the exterior margin of the joint.
The succeeding joints have a similar structure to those of the max-
illary palpi.

§ 173.

The antennae have three muscles which move them — an extensor,
which originates from the forehead in front of the eyes, and affixes
itself to the exterior margin of the basal joint ; a flexor, which ori-
ginates from the anterior apex of the inside of the skull, and affixes
itself to the inner margin of the basal joint ; and an elevator, which
originates exteriorly contiguous to the extensor from the margin of the
eye, and inserts itself at the lower margin of the basal joint.

The individual joints have each two muscles, namely, those known
from their situation as extensor and flexor.

Besides the above-named muscles there are other smaller ones,
which retain the pharynx and palate in their proper place. In Locusta
the muscles of the lips and tongue participate in this ; in the Coleo-
ptera they originate from the inside of the skull, and insert themselves
at the pharynx, or from the forehead itself when the processes of the
head do not advance so far. In Dyticus, from the skull of which two
long, bent, horny processes originate, which extend as far as the fore-
head, and enclose the pharynx between them, they originate from the
inner margin of these processes. In Melolontha, in which this internal
frame of the head is smaller, two come from the forehead itself, and
two others, smaller, on each side, from the clypeus : it is the same in
Locusta and Gryllus.

§ 174.

In insects with haustellate oral organs the muscles of the mouth are
much smaller. The Hymenoptera display the greatest conformity,
particularly as they have large mandibles, and we can even recognise
in their maxillae analogous muscles. The entire suctorial apparatus,
namely, the proboscis, with the maxillae, palpi, and labium, has a
moveable basis, formed of several united bony pieces, which, by means
of a soft but tense membrane, stand in connection with the margin of
the large oral aperture of the head. According to Treviranus * there
lie in this membrane one simple and four double horny bones. The

Vermischte Schriften, vol. ii. p. 117, PI. XIII. f. 1.

256‘

ANATOMY«,

two first (PI. VI. f. 5. 1.) lie in the anterior margin of this mem-
brane, in a transverse direction to the proboscis, but linearly with
respect to each other, directly behind the mentum. From the exterior
ends of each of these two pieces there originates a similar (2) bone,
which extends posteriorly upwards, the point of which touches a third
(3) bone, which furcates and descends from here to the posterior end
of the membrane. Both the prongs of the fork join at their ends a
fourth (4) uneven main bone, which lies transversely at the end of the
membrane, and opposite to the two first, which lie immediately behind
the mentum ; the fifth paired main bone (5) originates likewise at each
end of this fourth unpaired bone, and runs at the margin of the mem-
brane close to the horny aperture of the head. All nine thus construct one
valve, the anterior lobes of which are formed by the two first transverse
and anterior lateral bones, and the posterior lobes by the second lateral
bones, the fourth transverse and the two marginal bones originating
From its end. The articulation takes place at the point of con-
nexion of the two second and third bones. If the mentum (the same, a .)
be withdrawn, the membrane and bones lie like a valve together, but if,
on the contrary, the suctorial apparatus be distended, the membrane is
stretched out by means of the bones, and these push the chin forward be-
fore it. The motive apparatus of the butterflies is much more simple ;
in them a double band-shaped muscle runs along each half of the pro-
boscis, which clothes the entire cavity, leaving merely a narrow central
canal. Both these muscles roll up and distend the proboscis, and also
unite it with the head, inserting themselves partially upon the horny
wall, and partly upon the, indeed very small, internal frame-work of
the head. The smallness of their head arises from the disappearance
of the muscles of the mandibles. The same may be maintained of the
Hemiptera they also have but delicate muscles, which elevate and
withdraw the sheath, as well as still smaller ones, which rein the setae.
The Diptera, although they have in general a large head, derive it
from the preponderance of their eyes, for the muscles which pass to
their mouth are likewise abortive ; the fleshy proboscis alone, which we
consider as the labium, receives two large and tolerably broad band-
shaped muscles, which originate from two ridges placed internally
over the aperture of the mouth, and arched from the cheeks to the
clypeus, and which extend also to the apex of the proboscis. They
withdraw the proboscis within its cavity, and are therefore called the
extensors of the haustellum.

THE MUSCULAR SYSTEM.

257

§ 175.

B. Muscles of the Thorax.

The muscles of the thorax must be considered under several points
of view, which proceeds from the differences of structure displayedin this
portion of the body. The muscular system differs in insects with a
free prothorax from that of those with an immoveable connate one ;
to which we may add the muscles of the limbs, which likewise all lie
in the thorax, and a portion of which pass to the wings and the rest to
the legs. We have thus four main divisions into which the muscular
system of the thorax may be separated : we will therefore commence
with the system observed in insects with a free prothorax.

§ 176.

MUSCLES OF INSECTS WITH A FREE PROTHORAX.

The prothorax exhibits on each side four muscles, whereby it is held
connected with the meso- and metathorax.

The largest or superior retractor ( retractor prothoracis superior )
originates from the centre of the mesonotum with a broad basis, and
runs pyramidally to the prophragma or the anterior partition of the
mesonotum.

Opposite to it there lies a smaller lower retractor (retractor pro-
thoracis inferior ), which unites the internal furcate process of the
pro- and mesosternum.

The elevator ( elevator prothoracis ) is a small pyramidal muscle,
which originates on each side from the exterior margin of the
prophragma, and affixes itself to the corresponding fork of the
prosternum.

The fourth and largest of all, the rotator ( rotator prothoracis ),
comes from the posterior margin of the pronotum, passes beneath the
prophagma, and affixes itself to the exterior edge of the mesophragma
or the anterior portion of the metathorax.

The mesothorax, which, in the beetles, is the smallest portion
of the thorax, has but few muscles which unite it with the meta-
thorax.

One, the holder of the mesonotum, is a flat, thin but broad
muscle, which passes from the posterior wall of the prophagma to

258

ANATOMY.

the mesophragma. Another, which may be called the withdrawer,
goes from the lower margin of the prophragma to the wings ;
passing in its course closely to the exterior margin of the meso-
phragma, it assists to expand the wings, and at the same time
draws the mesothorax closer to the metathorax. Another holder of
the mesosternum, corresponding with that of the mesonotum, originates
from the posterior wall of the furcate process, and passes to its an-
terior portion upon the metasternum. (Le pretracteur de V apophyse
episternale poster ieure of Straus.)

The muscles of the metathorax are considerably larger. They may
be considered as the stem of the entire trunk of the beetle, to which
the other parts are all attached. It is thence that the true muscles of
the metathorax serve only for its own consolidation and strength, and
not for its connexion with other parts.

The largest and strongest of all is the dorsal muscle ( musculus
metanoti , V abaisseur de Valle of Straus), a thick powerful fleshy
bundle, which passes from the entire mesophragma to the metaphragma.
It falls properly into two halves, one of which belongs to each side of
the thorax, but both join together at the central line.

The lateral dorsal muscles ( musculi laterales metanoti , les pretrac-
teur s de Vaile of Straus) do not much yield in size. These originate
from the lateral portion of the metanotum, descend obliquely to the
metaphragma, and thus consolidate the dorsal plates.

The third connecting muscles of the metathorax run from the sides
of the metanotum to the side of the metasternum, but so that they
originate at the anterior margin of the metanotum, in front of the last-
named muscle, and pass obliquely to the posterior lateral part of the
sternum, and, consequently, to the cavity of the posterior legs. They
are divided into several bellies lying contiguously, all of which closely
unite the dorsal plate and sternum together, and, by their contraction,
they appear very much to promote respiration. I call them the lateral
muscles of the metathorax. They are what Straus calls les elevateurs
de Vaile.

We have already mentioned one muscle connecting the meta- with
the mesothorax. Besides which, we find thin prismatical muscles,
which, originating at the furcate branches of the internal process of the
sternum, pass transversely to the sides of the dorsal plates, and thereby
uuite it still more strongly with the sternum. They encompass below
the intestinal canal and above the straight dorsal muscles, and insert

THE MUSCULAR SYSTEM.

259

themselves contiguously to them at the mesothorax. They are most
distinct in the grasshoppers and Termites. In the Coleoptera several
are found upon each side, some of which come from the front and others
from behind from the back. I call them furcate dorsal muscles ( mas -
culi j ur ci-dor sales.) They are the flechisseur lateral de Capophyse
epistemale posterieure, Tabaisseur du ter gum , et V abaisseur du dia -
phragme, of Straus.

§ 177.

THE MUSCULAR SYSTEM OF INSECTS WITH A CONNATE THORAX.

While in insects with a free prothorax the greatest portion of the
entire thorax is occupied by the metathorax, in those orders in which
the thoracic case is closely united together, the mesothorax preponderates
in a like manner. The Cicada make the transit to this conformation,
for in these insects, although they possess a free and moveable pro-
thorax, still the greatest space is occupied by the mesothorax. The
large muscles of attachment and muscles of connection consequently lie
in the mesothorax in insects of this structure and in the Hymenoptera,
and indeed between the prophragma and the mesophragma, or, when the
former is very small, between the mesonotum and the mesosternal plate.
In the first case, it is the dorsal muscles which are chiefly developed,
and, in the latter case, the lateral muscles of the back. We thus find it
in Cicada, whose enormous lateral muscles of the back nearly entirely
supplant the true muscles of the sides. In the Lepidoptera , on the
contrary, the true dorsal muscles are the largest, although the pro-
phragma is but small : they consequently originate from the anterior
portion of the mesonotum, and so increase that they occupy two-thirds
of the thoracic cavity. In the Diptera, lastly, the lateral muscles are
very large. They originate, as is always the case, from the lateral
ridges of the mesonotum, and pass on to the mesosternum in front of
the cavities of the coxae. In Eristalis tenax I have distinguished two
separated lateral muscles on each side, the most posterior of which
inserts itself between the cavities of the intermediate and posterior
coxae. But this is possible in the Diptera only, for in them the meso-
phragma is wanting, or, rather, is so small, that it may be considered as
deficient. The dorsal muscles, therefore, are also distended between
the mesonotum and the metaphragma, but do not run parallely with
the former, but incline more obliquely downwards.

s 2

260

ANATOMY.

The connecting muscles of the sternal processes exhibit no other
differences than that the smaller these processes become, the more they
also decrease in size. In general, these processes are very small in the
above orders, and it is thence, probably, that I could never discover in
them the furcate dorsal muscles, if these positively exist, which I feel
much inclined to doubt from the course of my observations.

§ 178.

MUSCLES OF THE WINGS.

The true muscles of the wings originate, like the lateral muscles,
from the lateral parts of the sternum, and pass on with pointed tendons
to the ribs of the wings. We find their extensor the most developed,
and their flexor the least so.

The large extensor of the wing ( extensor alee viagnus ) originates
inwardly from the lateral portion of the sternum, closely contiguous to
its internal process, and proceeds transversely to the large marginal rib
of the wing, inserting itself at a plate-shaped tendon, which hangs in
immediate connection with the base of this marginal rib. (PI. XI.
No. 3. f. 8. a.) If the anterior wings be the largest, as in the Hymen-
optera and Lepidoplera, the dorsal muscle of the anterior wing is
likewise the largest ; but if the posterior wings are wanting, as in the
Diptera, their extensor is also wanting ; and if both are of equal size,
as in the Libellulce and the majority of the Neuroptera, their extensors
also are of equal size ; but if the posterior wings are the largest, as in
the Coleoptera and Orthoptera, this is likewise the case with their
extensors. The extensor of the elytra is, for instance, very small,
whereas the extensor of the wing is of great size.

The small extensor ( extensor alee parvus ) originates behind the
larger one from the lateral part of the sternum, or, frequently, from
its inflexion, formed by the cavity of the coxae, it runs contiguously
and parallel with the larger one as far as the articulation of the wing,
and likewise inserts itself, by means of a plate-shaped but smaller
tendon, to the second or posterior chief rib of the wing.

The flexors of the wing ( fiexorcs alee) are much smaller: they
originate from the parapleura, or, where this is not separated, from the
superior part of the lateral process of the sternum, and insert themselves
at the posterior margin, or upon the horny plates lying at the base of
the wing. In the Coleoptera, the flexor of the posterior wing consists

THE MUSCULAR SYSTEM.

261

of three bellies, which pass like three rays from the pleura, and insert
themselves at the most posterior horny piece lying at the base of the
wing (the axilloire troisieme of Straus).

Besides which, small muscles support the bending back of the wing,
and which originate from the plate-shaped tendon of the large extensor,
inserting themselves at other horny plates at the base of the wing :
when in action they cause the relaxation of the extensors, and are
thence called relaxatores extensorum.

§ 179.

MUSCLES OF THE LEGS.

The motive apparatus of the legs is much more complicated, both
from their being so much more moveable, and from their consisting of
several consecutive joints.

The coxae or hips receive the majority of muscles, but which are
adapted to the variations of their connection with the sternum.

If they, as in the Coleoptera, consist of a cylinder revolving upon its
axis, the flexor of the fore legs are placed at the posterior margin of
their inner aperture, and the extensors at the anterior margin ; but in
the posterior pair, the latter are placed at the posterior margin, and
the former at their anterior. Both come from the lateral parts of the
notum, or from the internal processes of the sternum. In Melolontha ,
Straus found in the fore legs, which, in all beetles, have the freest
motion, four extensors, which differed in size, and all came from the
posterior part of the pronotum, and but one flexor ; in the intermediate
pair, three flexors and two extensors, the longest of which came from
the margin of the prophragma, and the shortest from the internal pro-
cess of the sternum : the posterior coxae had, again, four extensors and
three flexors, some of which originated from the internal process of the
sternum, and the others from the dorsal and lateral plates. In the
water beetles, the very large posterior coxae are intimately connected
with the metasternum, and not articulated, from its receiving the
enormous muscles which move the remaining portion of the leg. The
muscles of the coxae are compressed by them, and the muscles which
move the leg pass from the internal process direct to the trochanter.

Such coxae as are free do not differ in structure from those which
are received within a cavity of the sternum, with the exception, that
their aperture exactly corresponds with the aperture of the sternum.

262

ANATOMY.

Their motion is rendered thereby indeed somewhat greater, but it
consists chiefly in revolving about the axis of the superior aperture of
the coxa ; and in such coxee we find likewise flexors which are inserted
at the posterior, and extensors at the anterior margin of the aperture,
or reversed, the latter behind and the former before ; and between
both, the articulating balls are found. But the muscles of motion
appear merely to proceed from the inner processes of the sternum.

The muscles which move the trochanters lie in the coxae, the
extensors on the exterior, and the flexors at the interior. In Melolonlha ,
Straus found in the first pair of legs three extensors and one flexor ;
in the two posterior pairs, however, but one flexor and one extensor.
The Dytici possess the largest muscles to the trochanters. In these
insects I found the extensor originate not from the coxa, but from the
lateral branch of the large furcate process, whereas, the weaker flexors
sprung from the inner surface of the coxae.

In the trochanter there is but one muscle the tendon of which is
inserted upon the head of the femur protruding into the cavity of the
trochanter, and it thereby lifts the thigh when it contracts, but lets it
fall again when lax.

In the thigh itself there are two muscles, one extensor, which lies
at the upper margin of the thigh, and which is attached to the superior
head of the tibia, by means of a long tendon, that lies within the
muscle, and one flexor, which lies opposed to it at the lower margin,
and which is correspondingly attached to a lower ball of the tibia. In
Locusta these muscles are very large, and have large bellies at their
base, varying according to the form of the thigh ; the thin membrane
lies quite free for about one-third of the length of the femur, but it
receives above, close to its connexion with the tibia, where the thigh is
somewhat broader, a narrow flat auxiliary muscle, which springs
obliquely from the case of the thigh, and attaches itself to the tendon.

In the tibia there are also two muscles, which move the whole foot.
The extensor of the foot is the smallest ; it originates from the lower
half of the posterior and lower margin with a broad basal surface, it
becomes pyramidal, and attaches itself to the superior margin of the
first joint of the tarsus. The flexor of the foot originates above it at
the same spot ; it soon becomes more slender, and with its free tendon
it passes into the cavity of the first joint of the tarsus, it sends its
tendon on through this as through all the consecutive joints, and inserts
itself at an arch in the last joint, where the two claws are internally

MUSCULAR SYSTEM.

263

connected ; it consequently bends the whole foot, whereas the extensor,
by drawing the first joint, again extends it.

In the last tarsal joint we again find peculiar muscles, viz., one
which originates from the base of the claw, and affixes itself to the
tendon of the tarsal flexor. It helps to bend the claws, and is thence
called ßexor unguium . The other originates with a broad base from
the inner wall of the superior surface of the claw-joint, and runs,
becoming pyramidal, to an arch connecting the two claws. It raises
the claw, and is therefore styled extensor unguium .

§ 180.

C. Muscles of the Abdomen.

The collective muscles of the abdomen serve partly to connect it
with the thorax and partly to unite the internal organs with it, and
they are thence divided into three groups.

The muscles which unite the abdomen with the thorax are, when
the abdomen is sessile, like all the abdominal muscles, flat, and like
bands, and originate from the posterior and lateral margins of the
thorax, affixing themselves to the first segment of the abdomen.

Those situated at the dorsal surface, which we call the superior
connecting muscles of the abdomen (muse, conjungentes superiores, s.
dorsales ), are divided into several contiguous bellies, which run flatly
from the metanotum and metaphragma to the first dorsal plate. The
lower connecting muscles, which lie upon the ventral surface (muse,
conjung. inferiores , s. ventrales), come from below, from the posterior
margin of the metasternum, and pass between the femoral cavities to
the first ventral plate.

Between both lie the lateral connecting muscles (m. conjung. late-
rales), which come from the lateral margin of the metasternum and
the lateral plates, and, passing into the cavity of the abdomen, uniting
themselves to the lateral wings of the first or second ventral plate.

In insects with a petiolated abdomen all these muscles, it is evident,
cannot be present, but instead of the dorsal muscles we find a single
large band ( funiculus of Kirby and Spence), which originates from
the inside of the metaphragma as a pyramidal muscle, passing with
its point through the hole at the end of the metaphragma, and affixing
itself to a short tooth which lies at the anterior margin of the first
dorsal plate (PI. XII. No. 2. f. 9. a.). The dorsal and ventral plates
of the first abdominal segment are prolonged into a broad upwardly

264

ANATOMY.

bent and gradually widening process, which is provided on each side
with a longitudinal groove (the same, b.}, to which a corresponding
process of the inner margin of the metaphragma fits. Besides the
abdomen and thorax are still more intimately bound by means of a
flexible membrane surrounding the large aperture (the same, fig. 7 and
8. a, a.). I have also plainly distinguished two flat lateral muscles,
which pass from one part to the other.

The connecting muscles of the abdominal plates may be divided into
the dorsal and ventral muscles.

The dorsal muscles are two large, broad, but flat band-shaped
muscles, which run from the first to the last abdominal segment, and
are throughout intimately united with the connecting membrane of
every pair of plates.

The ventral muscles are smaller, and do not pass in one line, but
only between every two contiguous ventral plates, taking an inward
oblique direction, so that their exterior boundary forms a zig-zag line.

I also found in Locusta transverse ventral muscles, which originating
from the descending ends of the dorsal plates, run transversely
across the ventral plates. They contract the cavity of the abdomen,
and thereby especially promote expiration. The abdominal muscles in
general seem less to connect the segments than to promote the freer
expiration of the air.

The remaining muscles of the abdomen, which raise and sink the
last plate, and at the same time unite the cloaca with the surrounding-
parts, are subjected, like that organ itself, to so many differences, that
a general description will be possible only when a tolerable number of
insects of all orders and families shall have been examined. From all
observations hitherto made it appears that both the dorsal and ventral
plates receive an extensor and a flexor, which originates from the penul-
timate plate, and affixes itself to the terminal one, the former more
exteriorly and anteriorly, and the latter more interiorly between the
preceding, and extending further to the apex.

The muscles of the cloaca and of the colon originate from the cir-
cumference of those organs, and pass as broad and fiat bands to the
dorsal and ventral plates, surrounding them. Both only serve to
retain the cloaca', and colon in their places when the faeces are
voided from the latter, or when the vagina or penis are protruded from
the former.

The muscles peculiar to the penis and the vagina, _ lastly, differ as

MUSCULAR SYSTEM.

265

much in form as those organs themselves. We have already taken a
general notice of them in our description of those organs. Different
layers are detected in them, the exterior of which retains and turns
hack the prepuce ; the inner ones, which lie between the valves them-
selves or pass on to them, open and shut them. Straus, in his anatomy
of the cockchafer, has given a very elaborate description of all these
muscles as they are found in that insect, and which is the less desirable
to be repeated here, as from the (indeed but limited) investigations
made by myself in other insects, they are subjected to very considerable
differences. The more comprehensive representations of all the modi-
fications of the external as well as internal sexual organs, which I
purpose one day undertaking, will then serve to fill this gap, and until
then these indications may suffice.

§ 181.

THE MUSCULAR SYSTEM OF LARVJE.

The muscular system of the larvae of those orders of insects having
an imperfect metamorphosis agrees with that of the perfected creature,
with the exception of the mere indication of the presence of the
muscles of the wings ; we have therefore nothing further to say of
them than that these muscles of the wings, during the several moult-
ings, and particularly during the pupa state, acquire the size they are
intended to retain during the imago state of the insect.

But the muscular system of the other orders, particularly of the
Lepidoptera and Hymenopiera, is very different ; the larvae of the
Coleoptera display much more conformity with that of the developed
beetle, for they are of all the most perfect larvae, and in the structure
of their feet agree very much with their perfected state.

The most conformable muscular distribution in all larvae is found in
the abdomen, in which two straight, broad, band-shaped muscles
descend both the ventral and dorsal sides and connect every two seg-
ments together, the muscle itself being intimately united with the
connecting membrane of the several segments.

Beneath these two large muscles, which may be called the longi-
tudinal muscles of the back and belly, lie smaller ones, which pass
obliquely from the connecting membrane at the anterior margin of a
joint to the corresponding part of the posterior margin of the same
joint, which may be therefore called the oblique dorsal and ventral
muscles. They strengthen the connexion of the joints together, and

266

ANATOMY.

contract the body during expiration. They appear to be wanting in
smaller coleopterous larvae, which are enveloped in a horny case ; in
the robust fleshy caterpillars there lies beneath them a third layer of
muscles, which take the same direction as the preceding, but differ
from them by their shortness and their separation into several parallel
fasciculi. They may be called the smaller oblique dorsal and ventral
muscles, and those above described as the larger superficial ones, and
the smaller ones as the deeper.

We observe, besides these ventral muscles which run parallely in
the longitudinal axis of the body, others which connect the dorsal plate
of each segment with the ventral plate. They originate contiguously
to the deep oblique ventral muscles with a broad basis, contract pyra-
midally by degrees, come then outwards, close to the direct ventral
muscles, and ascend on the outside of the straight dorsal muscles to
the dorsal plates, inserting themselves contiguously to the deep oblique
dorsal muscles upon the dorsal plate. I call them musculi ventri-
dor sales. In larger caterpillars, for example, the Cossus ligniperda *,
we can distinguish several layers and bundles of these muscles, and it
consequently is not difficult to make the number of the muscles of a
caterpillar amount to 4061 if, as Lyonet maintains of the goat-moth
caterpillar, each particular fasciculus be a distinct muscle f.

Exteriorly, contiguous to these muscles, there lie beneath each
other, and close to the lateral wall of each segment, several fasciculi
of oblique and crossing muscles, which strengthen still more the con-
nexion, and which, from their situation, may be called the lateral
muscles. With their diverging ends they embrace the spiracles of the
caterpillar, and they appear to assist chiefly in closing them after
expiration.

The muscles of the three first segments, which subsequently form
the thorax, are more numerous, for besides the usual connecting
muscles we here also find those of the legs, as well as the commence-
ment of the future muscles of the wings.

The longitudinal dorsal and ventral muscles are here in general
narrower, that they may make room for the other muscles, yet they so

* Consult Lyonet, Traits Anatomique, &c. ä la Haye, 1760, 4to. PI. vi. vii. & viii.
t* According to Lyonet, the number of muscles found in the head amount to 228,
those of the body to 1647, and those of the internal organs to 2186, making an aggregate
of 4061. Traite Anal. p. 584.

MUSCULAR SYSTEM.

267

develope themselves, at least the dorsal ones, and particularly during
the pupa state, that they subsequently present themselves as the large
dorsal muscles, distended between the phragmata. The straight ventral
muscles, on the contrary, so contract together, that they transform them-
selves into the small connecting muscles of the internal sternal pro-
cess. The lateral muscles again enlarge, and then exhibit themselves
as the large lateral muscles of the thorax.

The crossing pectoral muscles are peculiar to the thoracic segment.
They are the small band-shaped muscular strips on the pectoral side,
originating from the posterior margin of the first thoracic segment, and
running obliquely to the lateral parts of the following thoracic segment.
With their lower shanks they embrace the nervous cord, and cross each
other precisely over it, that coming from the left passing over to the
right and those from the right to the left ; each passes directly through
the straight ventral muscle, and affixes itself to the exterior wall of the
segment. In the perfect insect they exhibit themselves as the above
described furcate dorsal muscles. In the larvae of Coleoptera I found
besides transverse pectoral muscles, which originating at one side of
each of the three thoracic segments passed over to the opposite side, and
in the first and third segments covered the nervous cord, but in the
second were covered by it. I have not detected its development and
conformable appearance in the perfected insect.

The muscles of the legs correspond evidently with those of the per-
fect insect. The profoundest, or muscles of the coxae, come from the
lateral parts of each segment, and insert themselves at the inner
margin of the ring of the coxa. In larvae with long and large legs
there is found at the inner lateral part of each thoracic segment a pro-
jecting horny ridge, which passes over the cavity of the coxae, whence
spring all, or at least the more deeply seated, muscles of the coxae,
whereas the superior ones pass over this ridge, coming from higher
situated parts of the thoracic case. The muscles which move the
thighs lie in the ring of the coxae, and form three or four narrow fasci-
culi ; thus also in each successive joint is found the muscles of the
third in advance. The last joint, or claw, the preformation of the
subsequent tarsus, receives two muscles, which originate with several
heads from the several rings of the foot, both from their superior and
inferior sides, and all are attached to two tendons which are again
attached to the inferior margin of the claw. Their common contrac-

268

ANATOMY.

tion bends the claw with great force, and retains it in this situation.
We find no extensors of the claw joints.

The ventral feet of caterpillars receive, according to Meckel, three
muscles, an anterior and a posterior one, which spring from the cor-
responding membrane of the ring, and attach themselves to the inner
wall of the tube of the foot. The central one is larger than both the
others, and originates from a higher spot of the lateral part of the seg-
ment of the body. It here originates with a broad basal surface, and
runs down, contracting gradually as far as the centre of the foot sole.
It admits of being divided into two halves, and has consequently been
described by Lyonet and Cuvier as double.

The rudiments of the muscles of the wings are upon the whole very
indistinct, and very difficult to discover with certainty among the many
muscular strips of the thoracic segment. In the caterpillar of the
Cossus I consider those muscular strips which pass obliquely from the
posterior lateral margin, and anteriorly ascending upwards, as such
incipient muscles of the wings*, particularly as in the following
ventral segments no corresponding muscles are found. I found similar
strips in other larvae which I investigated, for example, in that of
Calosoma sycophanta.

The muscles, lastly, which bend the head to the thoracic segment,
and which move it, may, as in the perfect insect, be divided into an
extensor, a flexor, and a rotator of the head.

The extensors of the head form several layers over each other, the
most profound of which is nothing else than a continuation of the
dorsal muscle, and which attach themselves to the superior margin of
the large occipital aperture. Above these lies a narrower one, which
distends posteriorly, being attached at the occipital aperture between
the preceding, and originating at the anterior margin of the
second thoracic segment t- Other small strips, which lie above it,
originate from the centre of the pronotum, and pass over it to the
corresponding margin of the occipital aperture.

The flexors form three similar layers. The innermost layer is a
continuation of the longitudinal ventral muscle; the second, which
runs obliquely, comes from the anterior margin of the second thoracic
segment, and affixes itself between and beneath the former, at the

Lyonet, PI. VIII. f. 4.

t Ibid. PI. VI. d, d.

THE ORGANS OF SENSATION.

269

inferior margin of the occipital aperture. The third is formed by
small muscular strips., which originate from the pectoral plate of the
first segment of the body, and affix themselves beneath the former at
the large occipital aperture.

The rotators are divided on each side into two fasciculi, the superior
one of which springs more from the dorsal side, and the inferior one
from the pectoral side of the first segment of the body, and insert
themselves in the skull, closely contiguous to the margin of the occi-
pital aperture. The inferior ones are in general the shortest bundles,
and the superior ones the weakest. They both appear to me to be
merely modifications of the oblique lateral muscles, as those profounder
extensors and flexors may possibly be merely transformations of the
oblique dorsal and pectoral muscles.

The muscles lying in the head itself, which move the oral organs
and the antennae, agree so much in form, situation, and insertion with
those above described belonging to the perfect insect, that their small
divarications, which proceed from the less developed state of the ske-
leton of the head, require no further notice, particularly as they stand
in precise connexion with the various forms of the head, and their
special description consequently exceeds the boundaries of our object.
We must here, however, notice of the apparently headless larvae of the
Diptera, that the most anterior membranous segment of the body
takes the place of the head, and that its anterior orifice is the mouth,
which is armed with several, generally four, frequently bent setae, which
receive their peculiar extending and withdrawing muscles. They lie
withdrawn in the bag-shaped oral cavity, and appear, from their
darker colour, through the pointed anterior end of the larva as a black
body.

FOURTH CHAPTER.

OF THE ORGANS OF SENSATION.

§ 182.

The organs of sensation are the last portions of the bodies of insects
that we have to examine, and at the same time also the most simple;
for the commerce of insects with the external world, although consi-

270

ANATOMY.

derably more multifarious than in any other invertebrate animal ; yet
it does not unfold itself to that universal intercourse found in the
superior animals. But they are nevertheless sensible to every possible
external impression, and indeed for many more sensibly so than the
class of fish immediately above them, which, however, and this supports
the above assertion, are provided with distinct organs of hearing and
of smell, which are wanting in insects, although they require them
much more in the so considerably more tenuous element they inhabit,
than the fish, which pass their lives as it were concealed.

It is thence evident what we understand by organs of sensation,
namely, all forms which may be considered either as direct conductors
of immediate feelings, or as the recipients of higher and more distant
perceptions. To the first we may class the nerves, to the last the organs
of the senses, and in insects especially, the eye.

The nerves, which are the foundation of all the organs of sensation,
consist of fine fibres, which appear to be composed of the consecutive
disposition of solid globules. These atoms, from which all nerves
appear to be originally formed, preponderate so much in insects, that
we never detect in the ganglia and in the nervous cords but rarely
a fibrous formation, which would admit of the conclusion of its being
formed of a concourse of individual threads. The nervous mass is
contained within a very delicate structureless and perfectly transparent
membrane, the nervous sheath (rieurilema) , which appears to be the
mould of the entire nervous system, at least in insects. In it the
nervous mass is enclosed, which is a soft pulpy substance which flows
out when the sheath is opened. Upon a first superficial examination,
the chief nervous cords of insects, at least both the large ventral cords,
appear to be formed of several contiguous fibres, parallel stripes being
observable in them ; but these disappear upon a closer inspection, and
each nervous cord is found to be nothing else than a tube formed
of the nervous sheath filled with the nervous mass. The apparent
striature proceeds from the globules not being irregularly placed, but
disposed in longitudinal rows. Thus individual nervous cords appear,
and they even become so when, as in the superior animals, the
mass thickens, and thereby presses the globules together, and the
neurilema falls down between the striae.

The nervous mass itself consists of two different substances, namely,
the firmer, white central mass, and the softer, darker-coloured cortical
substance, and which is sometimes of a beautiful carmine, according to

THE ORGANS OP SENSATION.

271

my observations in the caterpillar of Noctna Verbasci *. But they
can be clearly distinguished only in recently opened insects: in those
which have been long immersed in spirits of wine, the former darkens
by degrees, and the latter becomes discoloured, so that neither exhibit
any longer a difference. The cortical substance appears to be deficient
in the filaments, and merely the white milk-coloured core appears to be
present : these, therefore, are in general brighter, and do not at all
participate in the colouring of the ganglia.

With respect to the general form of the nervous system of insects, it
presents itself as a double cord running along the ventral side, which
from segment to segment is re-united by ganglia. Two of these ganglia
lie in the head, one above the pharynx, the other beneath it, and together
form the brain, whence pass the nerves of the senses to the eyes,
antennae and oral organs. In the same way there spring from each of
the successive ganglia a number of lateral branches, which are subjected
to manifold differences, the three first of which pass to the legs, wings,
and muscles of the thorax ; those of the following ganglia to the
muscles of the abdomen, to the posterior end of the intestinal canal,
and to the organs of generation. The anterior portion of the canal,
namely, the crop and the stomach, has its peculiar nervous system,
which is formed by several auxiliary ganglia lying in the head.

Our investigation of the nervous system will thence fall into the
following subdivisions.

1. The brain with the nerves of the senses originating from it.

2. The ganglionic ventral cord with its branches.

3. The nervous system of the oesophagus and stomach.

To this we may add the organs of the senses themselves, of which
the eye alone will require a particular description ; as for the majority
of the remaining senses, no determinate organs have yet been fully
ascertained.

* This reminds us of the red nervous points in many of the lower animals, namely, the
Infusoria, especially the Rotatoria. Ehrenberg, in his admirable work upon these begin-
nings of organisation, considers these red points as eyes, but they are evidently nothing but
a mass of the nervous substance.

272

ANATOMY.

I. The Bra IN.

§ 183,

The brain ( encephalum ) of insects consists of two ganglia, one of
which passes over the pharynx and the other beneath it * ; both are
connected by means of nervous cords, which run from the upper to the
under, and which embrace the oesophagus. I consider that which lies
above as the cerebrum of the higher animals ; the lower one, on the
contrary, as the cerebellum : and, indeed, because, as in the higher
animals, the nerves of the superior organs of the senses, namely, of the
eye, spring from the upper ganglion ; and from the lower one, on the
contrary, the nerves of the mandibles, lips, and tongue proceed. It
must not appear strange that the nutrimental canal passes through' the
brain, particularly as the entire spinal cord lies beneath the intestinal
canal, and that the entire dorsal side of the higher animals is transferred
to the ventral side of insects. We are convinced of this by the situation
of the limbs and their connexion with the thorax, which also takes place
at the ventral side, whereas, in the superior animals, they pass from
the back, and, besides, the structure of the plates of the breast, which so
completely imitate the spine of the superior animals that no doubt can
be fairly entertained of their analogy, and of which we shall speak
more fully below. But whosoever should think the assertion absurd
that the oesophagus passes through the brain, we will merely remind him
of the certainly still more striking circumstance in the mollusca, in
which the colon passes through the heart, an assertion which has found
no contradiction, although both organs in the higher animals are far
more distant from each other than the brain and oesophagus.

§ 184.

The Cerebrum.

The cerebrum (PI. XXXI. and XXXII. a, a, a,) is a nervous cord
of a yellowish white colour, lying transversely across the oesophagus.

* J. Müller asserts of Phasma gigas , that the brain lies beneath the oesophagus (Nova
Actae, T. xii. Pt. 2. page 568), which I much doubt, notwithstanding my conviction of the
general perfect accuracy of his investigations. He distinctly describes the cerebellum, and
he has overlooked the cerebrum, which lies over the oesophagus.

THE CEREBRUM.

273

generally forming two ganglia. This cord sends off a branch on the
opposite sides to each eye, which is the optic nerve. Its entire cir-
cumference is covered by a thin transparent membrane, which loosely
surrounds it, and which in many cases, as for example, in Dylicus,
is beset with small darker knots, placed in regular squares (PL
XXXI. f. 1). The large muscles of the upper jaw spread above
it, extending upwards to the skull, so that it is entirely covered by
soft parts. The general form of the brain varies in as far as the two
hemispheres are more or less separated. In the Coleoptera they
approach closely together, and indeed so closely that they form but one
stripe, which is merely swollen on each side near the middle ; in other
instances, as for example in Gryllus migratorius, the two hemispheres
are nearly entirely separated, and are attached together by a central
thin nervous cord only, analogous to the corpus callosum of the superior
animals. The nerves which pass from the cerebrum are: —

1. The nerve of the antennae ( nervus antennalis). It originates
from the anterior margin of each hemisphere, but more exteriorly
when the antennae are lateral, and centrically when those organs are
inserted in the face. It runs as a simple undivided filament, which in
the first case passes over the tendon of the mandibles, and in the last
proceeds contiguously to the great flexor of the mandibles, to the root
of the antennae, immediately beneath the membrane which connects it
with the clypeus, but yet without sending off* branches. In many
cases it is equally thick throughout, in others, for example in the bees
and the cockchafer, it is more or less swollen at its base. When
arrived at the antennae the main stem still runs in this direction, and
very distinctly to the apex of the organ, and between the muscles, but
it gives off* on all sides delicate auxiliary branches to the muscles them-
selves. It is accompanied by a single branch of the trachea, which
originates on each side from the superior stem of the head, running
between the flexors of the mandibles, and branching off* according to the
ramifications of the nerve itself.

2. The optic nerve which originates from the lateral margin of each
hemisphere, with either a thicker or a thinner base, and extends to the
orbit, becoming gradually clavate. It varies much in form, but it always
retains the general characteristic of gradually distending. In Dyticus
it originates with a thin base, then suddenly distends, and afterwards
runs as a straight cylinder to the orbit ; in Melolontha it is not per-
ceptibly distinguished from the hemisphere of the brain, nor is its dis-

274

ANATOMY.

tension towards the orbit very distinct ; in Locusta the cerebrum is
smaller than the optic nerve, which springs from it with a very narrow
base, but which then very suddenly widens into a cone ; this is pre-
cisely the case also in the Libellulce and flies which possess large eyes
and a small skull, and in which the optic nerve of one eye is generally
much larger than the entire cerebral ganglion. When arrived in the
orbit it radiates into many branches, as we shall describe more fully
below, in the detailed description of the eye. The auxiliary optic
nerves ( nervi optici secundarii ), which are peculiar to such insects only
that possess stemmata, originate from the central portion of the
cerebrum, and extend as simple and very thin filaments to the spot
where the stemmata are situated, and gradually diverge from each
other. Thus each eye receives a distinct nerve, but which with its
colleagues originate from one portion of the brain. It is well known
that all the larvae of insects with an imperfect metamorphosis possess
merely stemmata, which are placed where subsequently in the perfect
insect the large reticulated eyes are found. The nerves of these stem-
rnata spring from the lappet-shaped distension of the cerebrum, some-
times separated (Calosoma, PI. XXXII. f. 1), sometimes united at
the base (caterpillars of the Lepidoptera), and run, each singly, to an
eye. In Vespa the nerves of the stemmata have a common stem (PI.
XXXII. f. 7.) ; in the bees they sit upon short clavate projections of
the cerebrum, and a distinct nerve does not seem to originate from
these knobs *. In the neuter bees we find close to these large knobs
two other small ones on each side, but which do not rise to the stem-
mata.

Besides these two main branches no other true nerves of the senses
originate from the cerebrum ; we observe merely smaller ramifications,
which give off branches partly to the muscles and partly form filaments
connected with the nerves of the cerebrum, and lastly, they may be
partly considered as the commencement of the nervus sympathicus.
But as below we shall devote our attention to this last system we will
reserve our investigation of its origin from the nerves of the cerebrum
until then.

The cords which connect the cerebrum with the cerebellum originate
from the lower or deeper portion of the ganglion, as the nerves of the
antennae do from the anterior or superior portion, and after the optic

* Treviranus, Biologie, vol. v. PI. II. f. 1 — 3. r, r.

THE CEREBELLUM.

275

nerve the former are the thickest of all the nerves it gives off. Their
direction as well as origin depends upon the situation of the head, for
upon its horizontal position they spring further below from the cere-
brum, but upon its vertical position we find them originate from its lower
surface. Their length also stands in direct proportion to the form of the
oesophagus ; they are long in broad and expansive ones, and shorter in
narrower ones. This is peculiar to haustellate insects, and in them
therefore both the ganglia lie closely together. We observe this
approximation of the two very distinctly in the bees, in which the
connecting cord is nearly deficient, so that the cerebrum and cerebellum
are quite contiguous, and there only remains in the middle between
both a small aperture for the oesophagus. These connecting cords of
the two brains very rarely give off auxiliary branches. I have observed
the only instance of this kind in Gryllus migratorius , in which a
smaller auxiliary branch originates at a little beyond half its length
upon the inner side, which is united with its opponent beneath the
oesophagus, running closely to that organ itself. Immediately in front
of their point of connexion each again gives off a smaller branch, which
runs back to the main connecting nerve of the two ganglia (PI. XXXI.
f. 7. d, d. and d*, d*.).

§ 185.

THE CEREBELLUM.

The cerebellum (PI. XXXI. and XXXII. b, b,) is generally a
cordiform or longitudinal ganglion ; it lies at the base of the cavity of
the skull, between the two projecting ridges of the previously described
internal skeleton of the head, and is entirely covered by the tentorium.
At the anterior portion of its lateral margin two strong nervous cords
originate from it, which rise to the cerebrum, running contiguously to
the tentorium, and enclose the oesophagus between them, forming the
nervous loop described above as encircling it. At its posterior end,
however, it again runs in two equal and very approximate filaments,
which pass through the occipital aperture, beneath the transverse bone
which divides it when present, out of the head into the thorax ; they
lie consequently very low in the neck, closely above the membrane of
the neck and the flexor muscles of the head. They are the origin of
the ganglionic nervous cord which runs along the pectoral and ventral
sides of the body.

Between these two connecting nerves of the cerebellum with the

t 2

276

ANATOMY.

portions of the nervous system lying before and behind it there ori-
ginate from it on each side from two to four nervous stems, which pass
to the mouth and the muscles of the head, and terminate in the various
organs constituting the mouth ; they are : —

1. The nerves of the mandibles (PI. XXXI. and XXXII. e, e),
which pass out of the anterior portion of the cerebellum, sometimes
between the branches of the loop of the oesophagus ( Melolontlia , PI.
XXXI. f. 5.), sometimes from the exterior margin, contiguously to
them ( Calosoma , PI. XXXII. f. 1.), and sometimes closer to the pos-
terior margin, beyond them ( Gryllus , PI. XXXI. f. 7-)* They give off
several delicate auxiliary branches to the flexor and extensor muscles of
the mandibles ; and lastly, accompanied by branches of the tracheae,
they pass into the cavity of the mandibles themselves, between the
tendons of both muscles. In the caterpillar of Cossus , according to
Lyonet, the nerve of the mandible comes in a remarkable manner as a
branch from the labium, and this receives four main stems (PI. XXXI.
f. 2. e, e.).

2. The nerves of the maxillae (PI. XXXI. and XXXII./,/. and
/*,/*.) originate sometimes in front ( Calosoma , PI. XXXII. f. 1.),
sometimes behind ( Melolontha and Gryllus, PI. XXXI. f. 4. and 7-)»
the nerves of the mandibles from the cerebellum, and run closely to these
to the maxillse, taking their course between the muscles, and passing
into the maxillae themselves. Here each divides, one branch going to
the palpus and extending to its apex, the other remaining in the maxillae,
spreading itself between its muscles. Sometimes (as in Calosoma, PI.
XXXII. f. 1. / /. and /*, /*.) these branches are divided at their
origin, and then the anterior one belongs to the maxillae and the pos-
terior one to the palpi ; both give off, even in the cavity of the head,
several branches, which pass to the neighbouring muscles.

3. The nerve of the labium (PI. XXXI. and XXXII. g, g.) comes,
when separated from those of the maxillae, from the centre of the
anterior margin of the cerebellum, and runs from here, very closely to
its opponent, direct to the labium, and here divides itself into several,
generally two, main branches, the inner one of which goes into the
tongue and' the outer one to the labial palpus. Where this nerve is
wanting ( Melolontha , PI. XXXI. f. 5.) branches of the nerves of the
maxillae supply its place, and this is precisely the case where the
tongue is small, hard, and cartilaginous. But it struck me as more
singular in the Locusla (the same, f. 7-)’ which, notwithstanding that

THE VENTRAL CORD.

*77

it is furnished with a large fleshy tongue, I could And neither lingual
nor labial nerves. In the caterpillar of Cossus ligniperda Lyonet
observed a connexion of the two labial nerves before they passed into
the labium ; from this point of connexion other branches originated,
which spread to the labium. Besides these the labium receives another
nerve (the same, f. 2. g, g.), which originates quite posteriorly, close to
the nerves of the maxillae, and gives off in front of the labium an auxi-
liary branch for the muscles lying in the head.

§ 186.

II. THE VENTRAL CORD.

The ventral cord ( medulla spinalis , s. veniralis ) presents itself as a
consecutive series of ganglia, every approximate two of which are
united by one or two equal nervous cords. In the last case, conse-
quently, this ventral cord consists of two equal nervous threads, which
from spot to spot are connected together, and form a common ganglion.
We have already spoken above of the structure of these ganglia and
threads, we will here merely add that I have never detected a crossing
of the two threads in the ganglion; they seem rather, upon their
entrance into it, to terminate, and the ganglion itself appears to con-
sist of a soft, uniform, granulated, nervous mass, which is enveloped
within a softer, frequently darker (for example, of a carmine colour in
the caterpillar of Noctua verba sei,) cortical substance.

The numbers of the ganglia differ in the several orders and families,
but we may consider that there is properly one to every segment ;
hence their number would amount at most to thirteen, and we find, in
fact, this number in many larvae, namely, in all the larvae of the Lepi-
doptera. Two of these ganglia lie in the head, and form the brain, the
three following in the thorax, and the last eight in the abdomen. Each
of them sends off two or three radiating nervous filaments, which ori-
ginate at both its anterior and posterior extremities, diverge from each
other throughout their whole course, and distribute themselves to the
muscles, limbs, and several of the internal organs.

Besides the main cords which the ganglia form in conjunction, we
find between those which are chiefly seated in the segments of the thorax
other connecting filaments, as, for example, I have observed in the larva
of Calosoma sycophanla, and shall therefore particularly describe.
The first pair of these auxiliary connecting filaments originates from
the posterior portion of the cerebellum (PI. XXXIX. f. 1. b, h, h.),

278

ANATOMY.

closely contiguous to both the main stems ; each diverges from the
main stem in its course to about half its length, and then approaches
it again as far as the spot where the main stem passes into the first
thoracic ganglion, and then rejoins it. A delicate auxiliary branch of
this exterior connecting nerve originates from it closely beyond its
middle, passing to the first radiating nerve of the first thoracic gang-
lion, which it joins. The second connecting nerve (the same, i, i.)
originates in the same manner from the first ganglion of the thorax as
the first does from the cerebellum, and unites itself at a right angle
with the first radiating nerve of the second thoracic ganglion. At
their point of union a small ganglion is formed, from which two new
radiating branches proceed, distributing themselves between the thoracic
muscles. The third auxiliary connecting nerve (the same, k, k.) springs
from the posterior end of the second thoracic ganglion, and passes into
the third ganglion, forming an arch near the main stem, from which
from two to three small nerves originate, and distribute themselves
to the muscles. An auxiliary nerve connecting the third thoracic
ganglion with the first abdominal one is not to be detected.

§ 187-

If we turn back from this general inspection of the auxiliary connect-
ing nerves of these ganglia, which, as far as I know, have not hitherto been
observed in any other insect, and certainly do not exist in many, par-
ticularly the larvae of Lepidoptera, as may be adduced from Lyonet’s
accurate anatomy of the caterpillar of the great willow moth, to the
differences of the chief form of the nervous system, we may adopt the
following as a very general law : —

The ventral cord has as many ganglia as there are freely moveable
divisions of the body.

This law is everywhere confirmed. The caterpillars of the Lepi-
doptera, whose similar segments have an equal motion, have as many
ganglia as segments. In the Diptera, in which the three segments of
the thorax are united into one, we find but a single large ganglion ;
lastly, in the larvae whose thick fat bodies exhibit no distinct segments,
the ganglia entirely disappear, and instead of a ganglionic we here find
a simple thoracic cord, from which the fine nerves pass off on each side.
We will inspect this in greater detail in the several forms of the
nervous system and their transformation during the metamorphosis.

A simple short ventral cord, destitute of ganglia, is found in many

THE VENTRAL CORD.

279

larvae of the Diptera , Hymenoptera, and Coleoptera. Among the
larvae of the Diptera I have found it in the rat-tailed maggot, and
have represented it in PI. XXXII, f. 3. It commences with two
branches, which spring from the large cerebral ganglion lying over the
oesophagus. These branches, which embrace the oesophagus, unite
beneath it into one flat, tolerably broad, nervous cord, which extends
to about the third pair of feet on the pectoral side, within the thoracic
cavity, and here obtusely terminates. On each side of this cord there
are from .eight to nine small ganglia, whence the nervous filaments, as
also at the obtuse apex of the cord, radiate posteriorly. The last, pro-
ceeding from the end of the cord, are the thickest ; they extend down-
wards to the end of the abdominal cavity, and here distribute them-
selves with their terminal branches to the colon and the convoluted
tracheae lying at the end of the abdomen.

We should doubtlessly find a similar structure of the nervous system
in the maggots of all the Diptera whose body is not divided into dis-
tinct segments. Upon the same principle, I think, I may conclude that
the fat and irregularly-jointed larvae of the Hymenoptera, namely, of
the bees and of the wasps, have a similar nervous system without
ganglia, and thence it would be explained how Swammerdam could
discover no nervous cord in the honey-bee *. In the larvae of Stra-
tiomys Chamceleon the nervous cord is likewise indeed considerably
shorter than the body, but it exhibits distinct ganglia, which, however,
follow immediately upon each other, and display no long connect-
ing cords, which we observe in the fly itself. According to Swam-
merdam’s figure f , we find besides the cerebrum and cerebellum ten
consecutive and contiguous ganglia, and each sends off radiating lateral
nerves.

Among the Coleoptera we perceive a similar nervous system without
ganglia among the larvae of the Lamellicornia. Swammerdam J and
Rösel observed it in the larva of the rhinoceros-beetle ( Oryctes nasi -
cornis ) ; in these also it is a very short ventral cord, which extends
as far as the proximity of the third pair of legs, and from the lateral
margins of which innumerable delicate nervous filaments proceed. In
this larva also the body is not separated into distinct segments and
joints, it exhibits rather irregular folds and constrictions, which are

* Biblia Naturae, p. 166. a. + Ibid. PI. XL. f. 5.

$ Ibid. PI. XXVIII. f. 1.

280

ANATOMY.

very evident anteriorly, but nearly obliterated posteriorly. In the
larvae of the Dytici I likewise found a short nervous cord with closely
contiguous ganglia, whence the auxiliary nerves proceed, and yet their
bodies exhibit twelve distinct segments without the head. Perhaps
this imperfect development of their nervous system is in relation to
their constantly dwelling in water ; at least the same structure in the
equally distinctly jointed larva of Stratiomys, which likewise con-
stantly lives in the water, points to one and the same cause of an
analogous imperfection.

The positive opposition to this abortion of the nervous cord is found
in the caterpillars of the Lepidoptera and the larvae of many beetles.
All these exhibit a ventral cord, which has as many ganglia as the
body has segments, and in which, like the segments of the body, all the
ganglia are of equal size. We must, however, here remark that a
ganglion is not found in each segment, but that they gradually approxi-
mate together, so that the last ganglion, which follows immediately
upon the preceding one without any connecting cord, is found as far
advanced as the anterior margin of the penultimate segment. Each
ganglion sends off four nervous filaments, the first pair of which
extend more anteriorly, and the posterior pair furnish the parts
lying behind the ganglion with their nerves. But the nerves of the
ventral cord are almost exclusively destined to the organs of motion,
and they consequently distribute themselves with their branches be-
tween the upper and lower layers of the muscles. In some cases the
most internal muscles, particularly those lying about the cavity of the
abdomen, receive a peculiar nervous branch, and which is found in the
larva of Cossus ligniperda, and which here does not originate from the
ganglion itself, but closely in front of it, from the there simple undi-
vided connecting cord ; it commences with a small root, which speedily
divides into two equal branches, which take an opposite direction *.
In the larva of Calosoma sycophanta I found six nervous filaments
proceed from each ganglion, the middle pair of which likewise re-
mained above the ventral muscles, whereas the anterior and posterior
pairs passed beneath. The nerves for the anterior portion of the
intestinal canal come from the cerebrum, and form a peculiar system,
which descends that canal ; the nerves of the sexual organs proceed
indeed from the ventral cord, but merely from the branches of the

* l-yonct, PI. IX. f. 1. 2, 2, 2.

THE VENTRAL CORD.

281

much-radiated terminal ganglion. We observe a nervous system com-
posed of thirteen ganglia not only in the caterpillars of the Lepidoptera,
but also in the larva of the Carabodea, the predacious beetles, the
majority of the Heteromera ( Melo'e , Lytia), the capricorns, and pro-
bably also in the Chrysomela ; in the fat footless larvae of the Curculios
I surmise there is only a short ventral cord destitute of ganglia.

§ 188.

We find every variety of number between these extremes of gan-
glionic structure. The law which regulates the number of these ganglia
is still undiscovered ; for that adduced by Straus, of its being regulated
by the relative greater or smaller mobility of the segments, appears not
to suffice : he maintains, namely, in general, that the immobility of the
segments together causes the disappearance of all the ganglia ; and as
a proof he cites the families of the Dylici and Lamellicornia , whose
abdomen has no ganglia; but is motion less in them than in the very
approximate Carabodea and in the genus Lucanus ? Certainly not !
This less degree of motion might be ascribed to the ventral plates, and
yet we find in the abdomen distinct ganglia. The number of active
organs found in a segment would seem rather to influence it ; at least we
observe the ganglia of the thorax of perfect insects always larger when
they are furnished with perfect organs of flight, but smaller than those
of the abdomen when the wings and the muscles which move them are
wanting, for example, Melo'e *. It therefore appears preferable to
describe the different forms of the nervous cord of perfect insects in
the series of their orders and families, for within those boundaries we
seldom observe variations.

The greatest number of ganglia is found in the nervous system of
the Orthoptera , Termites , Libellulce , and many families of the Cole-
opter a, viz. the Carabodea , Staphylini, Elaters , Buprestis, and the
Capricorns. In these the ventral cord exhibits immediately three
ganglia, which lie in the three segments of the thorax. These differ
in size, inter se, and indeed the smallest is found in the prothorax, the
largest in the metathorax, and the intermediate size in the meso-
thorax. The ganglion of the prothorax lies immediately in front of the
internal furcate branches of the sternum, at the very base of the horny
plate, covered by the muscles which run from here partly to the head

Brandt and Ratzcburg, Arzneithicre, vol. ii. part iv. PI. XVII. f. 2.

282

ANATOMY.

and partly to the coxae. Between the branches of this process, or
when it is distinctly furcate between the fork, the nervous cords pass,
proceeding over the connecting membrane of the pro- and mesothorax,
running closely to it, and thus proceed into the mesothorax, again form-
ing the second ganglion in front of the internal process of its sternum. If
the branches of the first sternal process be united in an arch the nervous
cord runs beneath this arch, and above, the muscles affix themselves to
the process of the arch ( Locusla viridissima, Termes fatalis , Calli -
chroma rnoschaturn). The branches of the second sternal process are
not in general closed, the ganglion and cord consequently lie here
freely, which is the case also in the third process. This, however, is
higher than the preceding, often as it were pediculated, so that the
ventral cord must raise itself that it may pass over this process into the
abdomen. In front of this elevation the third ganglion then lies, imme-
diately upon the surface of the sternum : it is the largest, and sends
off the thickest nerves, and the second ganglion lies nearer to it than it
does to the first, and thus, even in the nervous system, the more
intimate connexion of the two posterior thoracic segments is clearly
shown.

The nerves which originate from this ganglion vary in number ; the
first thoracic ganglion sometimes sends off two and sometimes three
branches on each side. In the first case the first branch runs to the
legs, the second to the muscles in the prothorax ; in the second case
both the first and third on each side are nerves of muscles, whereas the
central one is the leg-nerve. Three branches are also found on each
side of the second ganglion, the central one of which is a nerve of a
leg, and the first and third pass on to muscles. It is probable that
the anterior one gives off fine nerves for those contained within the
hollow cavities of the ribs of the wings. The third thoracic ganglion
also sends off three branches, which distribute themselves in a like
manner. Of these the central or leg nerve is always the thickest, and
most deeply seated, in as far as the direct muscles of the thorax, or
the connecting muscles of the thoracic processes, pass over it ; the
others, on the contrary, raise themselves over these muscles.

The number of the abdominal ganglia varies considerably in the
different groups. Insects with an imperfect metamorphosis, as the
Locustas , Termites, and Lihellulce, exhibit as many ganglia as segments,
viz., from seven to eight, the two last of which, however, are so closely
contiguous that they form one ganglion of a figure of eight. In the

THE VENTRAL CORD.

283

coleopterous families with abdominal ganglia we find in general not
merely fewer than the first named instances, but also fewer than in
their larvae. During their metamorphosis, namely, either two ganglia
appear to grow together, or else some wholly disappear ; that may be
the reason why the ganglia of the thorax are larger than those of the
abdomen, at least the growing together of the third and fourth ganglia
of the larvae of the Coleopter a is very probable, particularly as this
union is proved to take place in the Lepidoptera during their meta-
morphosis by Herold’s history of that state of them. We therefore
find in general in the perfected beetle only five ganglia, the two last of
which are drawn so closely together that they form an eight-shaped
ganglion. From each of these ganglia two undivided pairs of nerves
proceed, which are rarely ramose at their extremity, and which, as
well as the cord lying on the ventral plates, distribute themselves
among all the viscera of the abdominal cavity near the surface of the
plates. The radiating nerves of the last ganglion alone, which forms
the analogue of the cauda equina of the superior animals, distribute
themselves to the internal sexual organs and to the colon. In Carabus,
Hydropliilus , Cerambyx , Lytta , and Meloe there are but these five
ganglia, and never more.

Having observed in all these insects three distinct thoracic ganglia,
one for each thoracic segment, we now come to those orders and families
which have but two separated ganglia in the thorax. In the Coleopter a
the large family of the Lamellicornia belong here. The accurate
representation of the nervous system in Melolontha vulgaris in
Straus * exhibits a heart-shaped ganglion lying in the prothorax, from
which a robust nerve originates on each side, which speedily divides
into several branches, the central thickest of which passes to the
anterior leg, whereas the smaller ones distribute themselves between
the muscles of the prothorax. The second ganglion, lying in front of
the mesothorax, appears to consist properly of two closely contiguous
ones, at least the aperture perceived in its centre evidently indicates
an original separation. From the anterior division proceed the nerve of
the intermediate foot and several branches for the muscles, as well as a
nerve originating completely in front, which passes to the elytra; from
the posterior division springs the nerve of the wing, which gives off
branches to the muscles and the nerve of the posterior leg, which like-

* Straus, PI. IX.

284

ANATOMY.

wise sends off many brandies to the muscles. A third, also cordiform
ganglion, lies closely to the posterior division of the second, and is
seated, as well as that, in front of the tridentiform process of the meta-
sternum ; from it, as well as from the posterior margin of the preceding
ganglion, fine radiating branches extend, all of which pass over the
sternal process into the abdomen, and proceed to its ventral plates ;
two central thicker ones, the cauda equina , proceed to the sexual
organs and the colon, distributing themselves there with many fine
branches. The structure of the nervous system is similar in Dyticus
marginalis : the prothorax has its own ganglion, which, by means of
two thick and tolerably long nervous cords, is united to the cerebellum
(PL XXXII. f. 2.). This ganglion lies always in front of the internal
sternal process, and runs with its posterior cords through both its
branches. The second ganglion, still larger than the first, lies pre-
cisely upon the mesosternum, in front of the commencement of its
internal process ; from it originate, as well as from the anterior, several
nerves among which we distinguish at the first ganglion two large ones
for the anterior legs (a, a ), and at the second four thicker ones for the
posterior legs ( b , b. and c, c.). The nervous cord rises from this
ganglion, runs between the branches of the sternal process, and lies
here between the coxae as a short nervous cord with four ganglia, which
somewhat increase in size, whereas the first is scarcely one quarter so
large as the second thoracic ganglion. From the circumference of
these four ganglia numerous nerves originate, particularly from the
last, which, radiating, proceed to the apex of the abdomen, and espe-
cially distribute themselves about the sexual organs. These last four
ganglia consequently belong, as well as the third in Melolontha, to the
abdomen, but they, however, rise as high as the coxae, for here the
most important muscles are found, whereas in the abdomen but few
large ones are to be met with ; on which account also in both cases the
ganglia are wholly wanting in the abdomen.

This is not the case in the Lepidoptera and Hymenoptera, which
likewise have but two ganglia in the thorax, but in them the abdomen
also exhibits ganglia, namely, five in both orders, of which, however,
the two last are also very approximate ; and indeed in some cases, for
example in Philanthus pictus, they are grown into one, so that in it
we can detect but four distinct ganglia. The decrease of the ganglia
in the thorax arises in the Lepidoptera from the growing together of
most approximate ones, which takes place by degrees during the pupa

THE VENTRAL CORD.

285

state. Thus, from the first and second ganglia of the caterpillar the
ganglion of the prothorax originates, from the third and fourth the
common very large ganglion for the connate meso- and metathorax ; the
fifth ganglion of the caterpillar, as well as the sixth, entirely disappear;
the seventh to the eleventh are found likewise in the imago. The
ganglion of the prothorax lies in both orders between the branches of
the internal sternal process, and gives off, besides the thick nerve for
the anterior legs, finer branches for the muscles ; the ganglion of the
meso- and metathorax lies upon the central surface of the sternum, it
is very large, and somewhat long ; many nerves spring from it, eight
of which are particularly distinguished. Two and two form an equal
pair ; the first and third pairs go to the wings, the second and fourth
to the feet, the remaining finer ones distribute themselves among the
muscles ; the last pair, lying closely to the connecting cord, passes with
this into the abdomen, and distributes itself in its first segment by
means of several filaments. In Bombus muscorum, according to Tre-
viranus* figure *, the second thoracic ganglion consists of an anterior
larger and a posterior smaller half ; but in many of the Hymenoptera
inspected by me, for example, in Vespa Germanica , I could not dis-
tinguish them, there was but a single large ganglion visible.

Lastly, there are insects in which but one ganglion is found in the
thorax, these are the Diptera. In them it is known that the thorax
is formed of but one undivided piece, which consists especially of the
mesothorax, to which the very small pro- and metathorax are but
appended. In the mesothorax also we find the chief muscles, namely,
the large direct dorsal and alary muscles, and accordingly a single
large ganglion, which lies upon the centre of the sternum, between the
intermediate and posterior legs. It takes the form of a long ganglion
(PI. XXXII. f. 4.), from which spring six main nerves for the legs.
I have not yet detected nerves for the wings proceeding directly from
the ganglion ; perhaps they may be branches of the nerves of the feet.
From the posterior margin of the ganglion a simple strong nervous
filament passes, which, running between the apertures of the coxae,
proceed into the abdomen ; closely before its entrance it gives off on
each side a fine nerve, but in the abdomen itself it has no branch as
far as the middle of its course. Here it first distends into a small
ganglion, from which on each side a fine furcate nerve originates. A

* Biologie, vol. v. PI. I. II. and III.

286

ANATOMY.

second somewhat larger ganglion lies some little distance beyond the
first, exactly between the sexual organs, and gives off branches to this
as well as to the colon. This description has been sketched from the
Eristalis tenax of Meigen ; in Musca vomitoria I found precisely the
same structure.

§ 189.

III. THE SYMPATHIC SYSTEM.

A peculiar nervous system, which hung connected with the cerebrum
by means of fine branches, and in its course spread itself about the
anterior portion of the intestinal canal, was formerly discovered by
Swammerdam in the larvae of the rhinoceros-beetle ( Oryctes nasi-
comis * * * §), and by Lyonet in the larva of the large Cossus f. Subse-
quent anatomists took no further heed of this discovery ; and until
Cuvier, who described some of the forms of these nerves, it was not
again thought of. Since then J. F. Meckel, Treviranus, and Marcel
de Serres have described this system in individual insects; but Joh.
Müller claims the greatest merit for giving the details of this system
n a distinct treatise %, having proved these nerves to be peculiar to
many insects, and for having represented them in several orders.
J. Brandt § has likewise completed the observations of Müller, and
has given a well-executed representation of the various relations of the
nerves in the caterpillar and imago of the silkworm. From these
earlier contributions, and from my own individual observations, I
deduce the following results : —

§ 190.

The Sympathie system is peculiar to all insects, but in the several
orders it takes a different form : we may distinguish in it two main
divisions. A single cord, which runs upon the surface of the oeso-
phagus and stomach, giving off delicate branches on all sides, and where
the oesophagus passes through the brain running with the oesophagus
beneath the cerebrum : and a double nervous web, consisting of ganglia,

* Biblia Natura, PI. XXVIII. f. 2 and 3.

t Lyonet, PI. XII. f. 1 . h.

+ Nova Acta Phys. Med. Soc., tom. xiv. part i. p. 73, &c.

§ J. J. Brandt, Beobachtungen über die Systeme der Eingeweidenerven. Isis. 1831,
p. 2003.

THE SYMPATHIC SYSTEM.

287

which originates on each side by one branch from the posterior portion
of the cerebrum running down the oesophagus, and giving off here and
there fine auxiliary branches to the single nervous cord. Both stand
in a certain reciprocal relation to each other, in so far as where the
double system preponderates the former diminishes, and where the
single cord is considerably developed the double ganglia with their
branches shrink up.

The single nervous cord is considerably most developed in the
Coleoptera, Lepidoptera , and Libellulce. It here originates with two
branches arched towards each other, springing from the anterior por-
tion of the cerebrum, contiguous to the nerves of the antennse. Both
branches unite at the centre, and form a small ganglion (ganglium
frontale), and from this the single nerve proceeds beneath the brain
(PI. XXXII. f. 6 — 8. a, a.). This, from its bending form, Swam-
merdam and Cuvier called the nervus recurrens. The arch is some-
times double, as in the silkworm (PI. XXXII, f. 6 and 7*)* the
Coleoptera , on the contrary, always simple (the same, f. 8.) ; but yet
in both finer branches originate from this arch, which sink to the
anterior wall of the oesophagus, and pass even into the labrum. In
some Coleoptera , for example, Melolontha, these arching branches are
so fine that they even escaped the accurate Straus ; he detected but two
delicate filaments to arise from the frontal ganglion, lying in front of
the cerebrum, which appeared to bend about the oesophagus. I also
have not been able distinctly to perceive in several beetles this con-
nexion of the frontal ganglion with the cerebrum. When the filament
has passed behind the brain it runs along the oesophagus as a simple
cord, which nevertheless gives off everywhere very delicate auxiliary
branches to the tunics of the oesophagus, as far as the stomach, and
here divides itself into two equal branches, forming at the point of
division a small ganglion, from which, besides the two main stems,
many other smaller filaments proceed. Where the stomach commences
in the craw, consequently in the predaceous insects, and at the ante-
rior half of the large simple stomach in the vegetable feeders, its last
very delicate branches terminate, for they sink between the tunics of
the stomach, and there lose themselves ; indeed, in the cases in which
the oesophagus is tolerably long, they but just reach the stomach itself,
without spreading themselves over it. This description of the dis-
tribution of the single nervous cord will suit also the Lepidoptera,
for in them also it never extends beyond the commencement of the

288

ANATOMY.

stomach, but furcates shortly before this spot, and ramifies into the
finest threads.

The double nervous system in these orders consists of four small
ganglia, which lie directly behind the brain upon the oesophagus. The
anterior generally somewhat larger ganglion (f. 6 — 8. b. b.) arises with
one ( Coleoptera ) or two ( Lepidoptera ) branches from one half of the
cerebrum, and sends outwards delicate branches about the oesophagus,
but inwards a branch which unites itself with the single nervous cord
lying between the two ganglia. The second smaller ganglion (the
same, b*. b *.) stands in connexion with the first by means of a nerve of
communication ; it also sends off fine branches, which run along the
oesophagus : indeed, in the Lepidoptera, it also unites itself again with
the unequal cord. This last ganglion of the double system was discovered
at the same time by Straus Dürkheim, and Brandt : the first was
discovered by Lyonet in the Cossus caterpillar, but its connexion with
the single cord escaped him.

§ 191.

The double nervous system attains its most complete development in
the Orthoptera, namely, in Locusta and Gryllus. In Gryllus migra-
torius (PI. XXXI. f. 6.), there are found immediately behind the brain,
upon the superior surface of the oesophagus, five different ganglia. The
central and smallest (6.) lies nearest the brain, in which its two halves
make considerable constrictions, being united on each side by means of
a fine branch within each hemisphere. Between these two connecting
branches this ganglion meets the single cord, which, coming from the
frontal ganglion beneath the brain, originates likewise with two arched
branches from the anterior side of the brain, and from the frontal
ganglion itself sends off delicate branches forwards. Posteriorly this
single nerve does not quit the central ganglion, but wholly terminates
in it. Two other ganglia, which lie closely to the central one (c. c.),
are the largest of all, and have the form of a figure of eight, and stand
in connexion with the central one by means of one, and with the brain
by means of two branches. At its posterior end two other branches
originate from it, the exterior of which is the longest ; both furcate,
the latter after it has first swollen at the point of separation into a
small ganglion (e.). Close to these two ganglia, we find at the lateral
margins of the oesophagus two other oval but somewhat smaller ones
( d . d ’.), which are connected with the central one by means of two, and

THE ORGANS OF THE SENSES.

289

with the brain by one only, but tolerably robust nerves. Two branches
originate posteriorly from them, but which speedily reunite in a smaller
ganglion (d* d *), which then sends off a long, rather strong filament.
This filament runs down by the side of the oesophagus, and passes with
it into the prothorax. The oesophagus here distends into the crop, and
about the centre of which, each nerve forms a small ganglion (f. f),
from which two furcate branches, which embrace the oesophagus, pro-
ceed : the nerve then runs undivided on until it attains the end of the
crop. Here it forms the second ganglion ( g . g.), which again sends off
three double branches, each of which furcates. The branches of these
furcate nerves, six in number, or twelve on both sides, pass between the
six caeca lying at the orifice of the stomach, and distribute themselves
over them in the most delicate threads. In Gryllus hieroglyphicus ,
according to Müller*, the upper ganglion is again found, but its rela-
tive proportion is not very evident from his representation ; the nerve
running down the oesophagus has no ganglia, but many fine branches
are given off along its whole course, In Acheta Gryllotalpaf , the
downward running nerves are very distinct: both give off auxiliary
branches, particularly to the sack-shaped distended crop. In the
proventriculus, they again unite to form a tolerably considerable
ganglion, whence many branches originate, which distribute themselves
over it. Blatta and Mantis have but a central single nervous cord,
which appears, however, to proceed from the ganglion lying behind the
brain.

IV. The Organs of the Senses.

§ 192.

Of all the several organs of the senses, the eye alone possesses a
superior development : nose and car are not yet proved to exist, and
taste likewise can be present only in a few, at least to a degree worthy
of investigation ; but touch, which never properly possesses a distinct
and constant organ, but, according to the differences of animal
organisation, is sometimes imparted to one and sometimes to another
organ, has, in the majority of the orders, peculiar organs varying in
their grade of development.

Of these senses, we will first examine that of sight, as the most
perfect.

* PI. IX. f. 5. + lb. f. 2.

290

ANATOMY.

The form, situation, number, and external differences of the eyes of
insects, have been already sufficiently described in the first division of
our present inquiry ; we can therefore presume that all these points are
known, and proceed at once to its internal structure. Upon turning a
preliminary glance to the history of the progress of these observations,
we shall find all the earlier investigations unsatisfactory. The facets
in the eyes of different insects were numbered, the optic nerve and its
radial branches were also known, and a distinction was made between
compound and simple eyes, without the peculiar structure of the latter
being detected. After such, upon the whole unsatisfactory, preludatory
labours* * * §, Marcel de Serres f undertook a more comprehensive investi-
gation of the eyes of insects, in which he, indeed, discovered much that
was new, but was far from exhausting the subject, which is evident
from the subsequent labours of Job. Müller J. It was reserved to this
indefatigable inquirer to give a comprehensible explanation of the eyes
of insects, and to lay the foundation of the correct doctrine of the sight
of insects with both compound and simple eyes. The following is the
result of his admirable investigation, confirmed by Düges §, in opposition
to Straus-Durkheim ||.

The simple eyes of insects agree entirely in structure with the eyes
of the superior animals, particularly of the fish. It is found in all the
larvae of insects with a perfect metamorphosis, and in many families of
perfect insects of all orders. The following Table will give a more
precise survey.

I. Insects with merely simple eyes.

a. The larvae of Coleoptera, Lepidoptera, Hymenoptera, Neurop-
tera, and Diptera (with the exception of Culex and the ap-
proximate water larvae, which possess compound eyes).

b. The Dictyotoptera, Thysanoura (with the exception of Machilis
and Mallophaga).

II. Insects with simple and compound eyes.

a. The majority of insects with an imperfect metamorphosis, —
consequently.

* Consult Schelver Versuch einer Naturgeschichte der Sinneswerkzeuge hei den
Insekten. Gotting. 1798. 8vo.

■f M£m. sur les Yeux composes, et les Yeux liss£s des Insectes. Montp. 1813. 8vo.

t Zur Vergleichende Physiologie des Gesichtssinnes. Leip. 1826. 8vo., and Suppt, to
it, in Meckel’s Archiv. 1828.

§ Annales des Sc. Nat. xx. 341. 6.

|| Ib. tom, xviii. p. 463.

THE ORGANS OP THE SENSES.

291

1 . Orthoptera collectively, without Forficula.

2. Dictyotoptera, Libellula, and Ephemera , have three simple
eyes, Termes but turn.

3. Hemiptera. The majority of bugs have two simple eyes ;
some, for example, Lygceus apterus, none. The majority
of Cicada have three simple eyes ; some, for example,
Membracis , Flala, but two. The water bugs, as Nepa,
Ranatra , Naucoris, Noionecta, Sigara , display no simple
eyes.

b. Of insects with a perfect metamorphosis :

1. The Diptera . Generally three, seldom two ( Mycelophila )
simple eyes. The Tipularia , Culicina, and Gallifica , are
excepted, as they possess no simple eyes.

2. The Lepidoptera. Two simple eyes in the crepuscular
moths and Nociuce (perhaps in all?)

3. All Hymenoptera have three simple eyes upon the vertex
(some neuter ants are blind, as well as the majority of
larvae).

4. Neuroptera. Three simple eyes as well as compound ones
in Phryganea, Semblis, Raphidia, Panorpa, Osmylus .

5. Coleoptera. Two simple eyes in Onthopkagus , Omalium,
and Paussus.

III. Insects with merely compound eyes.

a. All Coleoptera , with the exception of the above-named genera,
Anthophagus, Omalium , and Paussus, the two points upon
whose vertex are supposed to be simple eyes.

b. Besides, several already-named genera and families of other
orders, as, Machilis , Forßcula , Hydrocorides , Tipularia,
Culicina, Gallifica , Hemerobius, Myrmecoleon, Ascalaphus, &c.

c. The larvae of insects with an imperfect metamorphosis. In
the larvae of the Cicada and Gryllus, the simple eyes are indi-
cated by spots, and the compound ones have fewer facets than
in the imago.

With respect to the internal structure of the simple eye, there is
found beneath the very smooth hemispherical, or, at least, convex
transparent horny integument, a small globular transparent lens, which
lies closely attached to the horny integument, and tits into a corresponding
cavity in the inner surface of that integument. Behind the lens lies a
truly lens-shaped glassy body, larger in compass than the lens, corre-

u 2

292

ANATOJMY.

sponding with the entire circumference of the eye., but proportionately
less convex. Both hemispherical divisions of the glassy body are of a
different convexity, and, indeed, the upper is the flatter, and the lower
the most convex side. The rete or superior bowl-shaped distended
end of the optic nerve spreads itself at the posterior margin of the
glassy body. It closely embraces this body, which lies in it as in a
shell. It is again exteriorly covered by the pigment. This bends
itself in the entire circumference of the eye, up to the horny tunic, and
forms around the lens a small iris beneath that tunic. Where the
optic nerve spreads into the rete, the pigment covers it, but thus far it
comes entirely free from the cerebrum, as was shown above. The
pigment varies much in colour : in the majority of cases it is of a brown
red or dark cherry brown, sometimes black, or of a bright blood red.
In this case, or, rather, in general, the margin lying next to the horny
integument shines through it, and thus forms in the circumference of
the lens a beautifully coloured iris. It is more evident in the large
eyes of the scorpions and of the Solpugce, but even the small eyes of
insects exhibit an annular iris.

§ 194.

The presence of compound eyes is shown by the above Table.

Regarding their structure, the horny integument consists of many small
hexagonal surfaces, which correspond exactly with each other, and
cause the hemispherical, or, at least, convex figure of the superior
surface of the eye. Each of these hexagonal facets, the number of
which varies, and is sometimes very considerable, as the following list
of them shows,

Mordella .... 25,088

Libellula . . . . 12,544

Papilio 17*355

Sphinx Convolvulus . 1,300

Cossus ligniperda . . 11,300 *

CEslrus 7*000

Liparis Mori . . . 6,236

Musca Domestica . . 4,000

Formica 50

forms a distinct lens, convex on both sides, varying in thickness. The
proportion of its thickness to its transverse diameter is, for example, in
a sphinx, 1 : 2 ; in others, this lens is still thicker, which is especially

THE ORGANS OF THE SENSES.

293

the case in all insects with an imperfect metamorphosis. Nevertheless,
each lens is flatter in them than in other insects, and we must here
consequently regard every individual lens as cut at its margin, so that
merely the central most elevated portion remains. Were this not the
case in thick and flattish lenses, objects would necessarily appear
indistinct. In Gryllus hieroglyphicus, Joh. Miiller * detected the
proportion of the breadth to the thickness to be 1 : 7- The space at
the circumference of the facets is covered by the pigment collected
between the filaments of the optic nerve, so that each individual facet
is surrounded with a ring of pigment or kind of iris ; the disk, how-
ever, remains free and transparent. Upon the superior surface we
occasionally observe, particularly in the bees and flies, fine hairs pro-
jecting, which may be considered as analogous to the eye-lashes, as
they doubtlessly prevent the approach of external bodies, but at the
same time limit the visual circle of each facet to the space itself
occupies.

Upon the inner surface of each individual lens we find a transparent
crystalline cone, the convex surface of which touches merely the centre
of each facfct, but leaves a small space around the circumference free
for the ring of pigment. The circumference of each of these cones is
for a certain space not inclined but perpendicular, thus giving the
crystalline body a more cylindrical form, which, however, gradually
diminishes, and they internally run to a point, to which a delicate
filament of the radiating optic nerve passes. The pigment or peculiar
colouring matter, which occupies the whole inner space of the eye,
passes between these cones, enveloping the filaments of the optic nerve
as far as the facets forming the iris around the circumference of the
base of the cone. In this manner each individual facet with its crys-
talline body is separated from the other, and may therefore be considered
as a distinct eye. The length of these cones varies not only in different
insects, but often in the same, from its position being either marginal
or central. We may consider, in general, that, in such eyes which
form no segment of a circle, those cones which are found at the flattest
part of the eye are the longest, and the others situated at the more
convex parts, the shortest, but the basal surface of the cone does not
vary, but is always regulated by the form of the facet. Their length
cannot be precisely determined, but, in such eyes which form the

41 Where cited above, p. 241.

294

ANATOMY.

segment of a circle, or which are hemispherical, it is regulated by the
size of the entire sphere : larger and consequently flatter spheres, receive
longer ones, and smaller, and, therefore, more convex ones, receive
shorter cones. In one of the Noctuce, J oh. Miiller found the proportions
of length to the breadth of the base to be as 5 to 1 . In (Eschna , these
relations, according to Diiges’ figure, are as 10 to 1 ; the base itself
also rises so much, that it even appears conical.

As we have mentioned above, a filament of the optic nerve stands in
connexion with the apex of each cone. These filaments are thin,
extremely delicate nerves, which, like the rays of a sphere, originate
from the exterior surface of the optic nerve, and spread themselves to
the circumference, one passing to each cone. Nothing further can be
remarked of them ; a separation or radiating division of them has never
been observed. They bring the external portion of the eye into con-
nexion with the cerebrum, and may be therefore considered as the most
important conductors of the sense of sight. According to the figure of
Straus, this nerve somewhat distends where it joins the crystalline body,
and encompasses its apex, there forming a kind of retina ; but Miiller
and Diiges never detected this distension of the filaments of the optic
nerve.

The dark pigment spreads all over the entire eye between the filaments
of the optic nerve. It is a variously coloured, generally a dark purple
red, sometimes brighter {Mantis'), thickish fluid, which is transpierced
throughout by fine tracheal branches, which proceed from a trachea
surrounding the inner circumference of the eye like a ring. This layer
of colour consequently corresponds with the clioroidea of the higher
animals, which is both colouring matter and a vascular tunic. The
pigment in the majority of insects admits of being divided into two
layers, from its difference of colour. The external brighter pigment
displays very various colours, as is proved by the mere appearance of
the eyes. All bright, glittering metallic eyes, or such as are ornamented
with stripes and spots, derive their painting and markings from this
superficial pigment. I will cite here merely the green yellow eyes of
the butterflies of the genus Pontia and the banded metallic eyes of the
Tabani, the brassy coloured ones of the Hemerobia, and the beautifully
coloured eyes of so many other insects. The internal pigment is uni-
formly dark, but, likewise, it is not entirely similar in all insects, but
varies according to the families and genera. Mantis exhibits it bright
red, the moths violet, many butterflies of a blue violet, and other butter-

THE ORGANS OF THE SENSES.

295

flies, the Hymenoptera and Coleoptera , of a dark blue or entirely black.
Even in insects which possess but one pigment, the colour is not entirely
the same, but darker nearer the centre, brighter at its circumference in
the vicinity of the glass cone and lens. In some cases we discover
more than two layers of pigment, as, for example, in Gryllus hiero-
glyphicus , an exterior pale orange colour, a central bright red, and a
dark violet. The first and second were very thin, each thinner than
the lenses ; the innermost entirely filled the remaining portion of the
eye *.

Thus much upon the structure of the eye. We may here once more
repeat that this entire description is but an extract of Joh. Miiller’s
admirable treatise upon this subject, and that here merely the most
interesting portion of his results are stated. The subsequent labours
of Straus Dürkheim -f and Diiges do not equal those of the above
distinguished entomotomist, nor have they been able to add many new
discoveries or corrections of his.

§ 195.

Much obscurity still invests our knowledge of the hearing of insects.
G. R. Treviranus J has, indeed, discovered and described the organ of
hearing of the moths ; it consists of a simple thin drum, which is seated
at the forehead in front of the base of each antenna, and to which the
nerves of hearing, which are branches of the nerves of the antennae,
spread themselves without the intermedium of a hearing bladder filled
with water ; but this admirable discovery of his has not been confirmed
in insects of other orders, for a similar organ has not yet been detected
in them. After him, Joh. Müller § described the peculiar organ of the
grasshopper, which is seated on each side at the base of the abdomen ;
he considered it the organ of hearing, but incorrectly, as will be shown
below : it is more likely to be an organ of sound. Other earlier opinions,
for example, those of Ramdohr ||, who considered the anterior salivary
glands of the bees as organs of hearing, are partly, as this latter, recalled,
or else, as unsatisfactory, require no further notice. To these may be
classed Comparetti’s observations of bags and passages in the heads of

* Müller, p. 355. f Considerations General, &c., p. 409

X Annalen du Wetterau. Gesell, f. d. Ges. Naturk. Yol. i. Pt. 2. 1809.

§ Consult his Phys. du Gesischtssinncs. p. 438.

|| Mag. du Ges. Naturf. Berlin. 1811. 389.

296

ANATOMY.

individual insects, to which cavities nervous filaments were said to be
distributed*. It is evident that some misconception was here at work,
for no entomotomist, either before him or since, has seen any thing of the
kind. But as insects doubtlessly hear, as some, for example, the Cicada,
grasshoppers, many beetles, &c., produce a peculiar sound, which serves
to attract the attention of the female, they must evidently be provided
with an organ of hearing, which is either very recondite, or referred to
organs whose form does not evince their function. The antennae are
doubtlessly of this class, and, indeed, Sulzer, Scarpa, Schneider,
Borkhausen, Reaumur, and Bonnsdorf, considered them as organs of
hearing. That they are not organs of touch, is proved anatomically by
their horny hard upper surface, and physiologically by the observation
that insects never use them as such, this function being exercised by
other organs, namely, the palpi. Besides, the analogy of the crabs, in
which it is well known that the organ of hearing lies at the base of the
large antennae, speaks in favour of the adoption of the opinion of their
being in general organs of hearing. If after this hint we look to the
insertion of the antennae, we likewise detect here a soft articulating
membrane, which lies exposed, and which is rendered tense by the
motion of the antennae. This membrane, beneath which the nerve of
the antennae runs, might, without much inconsistency, be explained as
the drum of the ear, and thus would the antennae be transformed pelices,
which, as very moveable parts, would receive the vibrations of the air,
caused by sound, and act as a conductor to it. Whoever has observed
a tranquilly proceeding capricorn beetle, which is suddenly surprised
by a loud sound, will have seen how immoveably outwards it spreads
its antennae, and holds them porrect as it were with the greatest atten-
tion as long as it listens, and how carelessly the insect proceeds in its
course when it conceives that no danger threatens it from the unusual
noise. Carus f, Straus Dürkheim §, and Oken ||, are of the same
opinion, and which I have entertained for years, and endeavoured to
confirm myself in by numerous experiments.

* Schelver, as above, p. 51. f lb. p. 24. % Zootomie, p. 65.

§ Consid. Generales, p. 415, &c.

|| It was not unpleasing to me to find in the recent edition of Oken’s Naturphilosophie,
my opinion stated in almost the same words in which I wrote them down. Consult that
work, p. 421, No. 3355. The earlier edition of this work did not contain the idea. See
Vol. iii. p. 274, No. 3100.

THE ORGANS OF THE SENSES.

297

§ 196.

Much more doubt and uncertainty attends the observations and
opinions upon the organ of smell of insects. Reaumur, Lyonet, and
several modern French naturalists, consider the antennae as such, but
I would ask with what right? A hard, horny organ, displaying no nerve
upon its surface, cannot possibly be the instrument of smell, for we
always find in the olfactory organ a soft, moist, mucous membrane, fur-
nished with numerous nerves. No such tunic is to be found in insects,
at least in their head, or upon the surface of their bodies. Marcel de
Serres *, and before him, Bonnsdorf f , endeavoured to prove the palpi
organs of smell, he described pores at their extremities, namely, in the
Orthoplera, which passed through its soft apex into the interior, and
here distributed nervous branches ; he also considered that the tracheae
of the palpi opened into the mouth, and that thereby a constant stream
of air was kept through them ; but it is all fanciful without any
satisfactory foundation. The palpi have no pores at their extremity,
and their tracheae have no external orifice, Comparetti J found
cavities and cells beneath the frons, which nobody ever saw, either
since or before, and these he considers organs of smell. More recently,
F. Rosenthal § described a folded skin at the forehead, beneath the
antennae, to which two fine nerves passed, and which he considers as
the organs of smell of Musca domestica and vornitoria ; and he observed,
after the destruction of the part, a deficiency of the function which had
previously strongly exhibited itself. But it is with this as with the
discovery of the organ of hearing in Blatta ; we cannot reason from it,
as similar structures have not been observed in other insects, and pre-
cisely in the dung beetles, which have the sense so acute, the forehead
is covered with a homy shield, that it is wholly impossible odours should
pass through it. Indeed, in the burying beetles ( Necrophori ), which
decidedly possess the most acute smell of all the Coleopter a, have above
the mouth, upon the clypeus, a triangular yellow somewhat deep spot,
having the appearance of a membrane stretched over it, and this
might be considered the analogue of the organ of smell discovered by
Rosenthal ; but, upon closer inspection, this spot appears to consist
also of a horny material, and we therefore cannot conceive it possible

* Annal. du Mus. T. xviii. pp. 426—441.

t De fabrica et usu Palporum in Insectis. Aboae, 1792. X Schclver, p. 46.

§ Rcil’s Archiv. Vol. x. p. 427.

298

ANATOMY.

for scents to pass through it. This difficulty was endeavoured to be
obviated by imagining that they passed through the mucous membrane
of the mouth to that smelling membrane, in which case it might be
common to all insects, but which is not the case. For this explanation
of it appears to me forced, as well as a second advanced by Treviranus *,
wTho wishes to persuade us that the entire mucous membrane of the
mouth is the organ of smell, but then especially ascribes this sense to
haustellate insects.

A different opinion is that formerly advanced by Baster, Dumeril,
and, latterly, by Straus Dürkheim f , namely, that the margins of the
stigmata are smelling organs. We have, it is true, in favour of it, the
analogy of the organ of smell in the superior animals being seated at
the orifice of the respiratory organs, but that is absolutely all. The
mucous membrane, the nervous rete, and the nerves of smell, are all
wanting, or, at least, are not shown to exist. Perhaps^, however, the
tracheae may possibly be organs of smell, if not at their aperture, yet
in their terminal ramifications, as they conduct air to all the organs,
and particularly likewise to the brain. Hence would follow the
deficiency of a peculiar organ of smell, which, however, must strike as
singular when we reflect upon the lower situated crab. But water
organs and organs of humidity, and such the organ of smell evidently
is J, for it is only with a moist nose that we can smell, more easily
attain a certain degree of perfection than in those which live in a rarer
medium. I will merely refer to the difference of the organs of smell
in water and land birds, as well as to the observation that the organs
of smell in birds are proportionably less perfect than in the amphibia
and fishes, which evidently helps to confirm the law, and serves to
explain the deficiency of these organs in insects. Thus insects, ac-
cording to my opinion, would smell with the internal superior surface,
if I may so call it, which is provided all over with ramifications and
nets of nerves, since this is always retained moist by the blood dis-
tributed through the body and by the transpired chyle, the same as is
surmised of the superior mollusca, namely, the Pulmobranchia and
Cephalopoda , that their sense of smell is seated in their exterior inte-
gument and thus in a universally distributed smelling tunic.

* Vermischte Schriften. Vol. ii. p. 146. f Considerations, p. 421.

X The whales want the auxiliary cavities of the nose, which secrete the fluid, because,
living in water, they do not require them. See Rudolphi Physiol. Vol. ii. PI. I., p. 118.

THE ORGANS OF THE SENSES.

299

§197.

The tongue is always the organ of taste where present. We have
seen above that many insects, namely, the Orthoptera, Libellulte , the
majority of beetles, many Hymenoptera , and, indeed, all mandibulate
insects, possess a more or less distinct tongue ; we have but to ask,
may we consider this tongue as the organ of taste ? — Taste can be of
importance only to such animals as feed upon a variety of substances
and masticate them. In haustellate insects this is not the case ; they
always subsist upon one and the same food, and generally inhabit what
they feed on, and consequently less require this sense. Indeed, they
are wholly deficient in a fleshy tongue, which can alone taste, and when
present as stiff setae, taste cannot be spoken of. But that the fleshy
tongue which we find in the Libellula and grasshoppers is certainly an
organ of taste, is corroborated by its delicate and soft superior surface,
its greater abundance of nerves, and, lastly, the various nature of their
food, which is visibly slowly masticated, and furnished with saliva
from the mouths of the ducts of the glands lying beneath the tongue.
To these we may add the wasps and bees, which suck the honey of
various flowers by means of their tongue, which is provided at its apex
with distinct glandular points, that, besides the business of ingestion,
serve doubtlessly to taste and distinguish the various kinds of honey.
This may also doubtlessly be maintained of the in general soft
membranous tongue of the Staphylini. Some physiologists, for
example, Rudolphi, deny the sense of taste to insects ; others seat it
in the palpi , where it certainly does not belong ; and others, again,
Straus, for instance, discover it in the tongue, where it is doubtlessly
to be sought, and frequently sufficiently distinctly exhibited. The
abortion of the tongue in many mandibulate insects ought not to
surprise us ; its cause, as well as the abortion of the organ of smell, is
the preponderance of the function of respiration, as the tongue is like-
wise a humid organ, for, in insects, every organ, by reason of the
universal distribution of air in them, has a tendency to become dry and
horny. In this they again find their parallelism in the birds, whose
tongue is small, imperfect, almost cartilaginous, indeed frequently
( Pteroglossus ) perfectly horny, and resembling a feather, exactly
like the tongue of many beetles, for example, the Capricorns , in
the internal organs of which there is a strong disposition to become
horny.

300

ANATOMY.

§ 198.

Everybody will admit that insects, more than many other animals,
require a peculiar organ of touch, from their being encased in a hard
insensible integument. It is true the antennae have long had this func-
tion ascribed to them, but incorrectly ; the hard horny antennae may
possibly well detect the presence of objects, but certainly arrive at no
other precise perception, for this requires a soft organ clothed with a
very delicate covering. Straus Dürkheim * therefore justly wonders
how this function could have been ascribed to the antennae ; but he
astonishes us still more by considering the still harder feet as organs of
touch. By far the majority of insects have hard, horny, perfectly
closed foot-joints, and the few which are furnished with setae, feathers,
or pulvilli at their plantae or apex of their tarsi do not use them as
organs of touch, but merely to assist in climbing ; indeed, there are
some genera whose feet have soft fleshy balls ( Xetios , Thrips , Gryllus ,
Locusta ), but these instances cannot prove it throughout an entire
class. For the rest, his opinion loses still more probability, when,
instead of his tarsal joints other organs can be shown as instruments
of touch. These organs are the palpi, already indicated by their name.
If we inspect the palpi of the larger insects, for example, of the pre-
datory beetles, the grasshoppers, humble-bees, and many others, we
observe at its apex a white, transparent, distended bladder, which, after
the death of the creature, dries into a concavity seated at the apex of
the palpus. This bladder is the true organ of touch, the main nerve of
the maxillae and of the tongue spreads to it, and distributes itself upon
its superior surface with the finest branches. Straus f, who carefully
observed this bladder, explains it as a sense of a peculiar description,
analogous to the taste-smell sense ( Geruchsgeschmackssinn ) of the
JR uminantia, discovered by Jacobson, but just as little as a union of the
senses of smell and taste conditionates the presence of a peculiar sense
may we explain the palpi as sensual organs of a peculiar description : they
are, whence they were named, namely, purely organs of touch. The defi-
ciency of palpi in haustellate insects may be objected to here ; but have
not these in their long proboscis a better organ of touch, and do not we
find everywhere in nature in all the organs an evident adaptation to

Considerations, p. 425.

f Ibid., p. 427.

THE ORGANS OF THE SENSES.

301

their object ? Where the palpi are the sheaths of the proboscis, as in
the Lepidoptera and Hemiptera, they could no longer remain true
organs of touch ; and where they have grown into a fleshy proboscideal
sheath, as in the flies, this sheath is the organ of touch, and properly,
also, the palpus itself is considered as contained in it. If, however,
living insects have been observed, no further objection will be taken to
the exclusive function of touch exercised by the palpi ; who still doubts
who has observed the play of the palpi of the spiders previous to copu-
lation, or seen predatory insects fall upon an unexpected prey, and
feeling it upon all sides ? The common, well-known, domestic fly,
lastly, can daily convince us, when we perceive it moving from spot to
spot, and detect every drop of liquid and every atom of sugar with
the sheath of its proboscis formed of the labial palpi. It first feels
them, and then ravenously swallows them ; but this touch is never
exercised by its tarsi, but invariably by the sheath of its proboscis.

THIRD SECTION.

PHYSIOLOGY.

§ 199.

We have now, after the preceding description of the insect body,
both external and internal, arrived at the point whence we can survey
the life of insects in one large representation, and, as it were, overlook-
ing form, shall only endeavour to seize their spiritual effects. This is,
namely, the theme of Physiology, to exhibit to us in a simple but well-
ordered description all the phenomena of the organic world, which befits
it only as the abstract of living beings, and which must be considered
consequently as the results of animation, and as the necessary attendants
of life ; and as general physiology undertakes to solve this problem with
reference to the whole of animated nature, the physiology of a solitary
group can be expected merely to occupy itself with the description of
the vital relations of this group. Such a group is formed by the world
of insects, and the task of our physiology found. Here, consequently,
belongs all that does not refer to the description of form ; and here
belongs also every phenomenon which individuals or numbers of insects
have betrayed to the observer, however insignificant and unimportant to
the illustration of the whole they may originally appear to us ; and it is
its task to arrange these phenomena, and to reduce them to recognised
laws, and where this will not succeed, thence to prove the possible
falsity of a principle adopted as true. The observation of insects is
therefore the foundation of their physiology, and it will be only when
all the various phenomena of all the families, genera, and species shall
be fully known that a perfect solution may be expected to be given of
the problem of physiology; until then our knowledge will be but
fragmentary. But the difficulty of the fulfilment of this necessary
requisition is evinced by the number of years that have already passed

PHYSIOLOGY.

303

over the study of the insect world without more than one-hundredth
of our native insects having been observed throughout all the conditions
of their existence. But he who should wonder at this apparently small
amount of observation will at least admit that observation is one of the
most difficult occupations, and that to accomplish it as much earnest-
ness, skill, and luck are required as patience, leisure, and industry,
and that the former as well as the other requisitions are not found every
day in everybody. We justly, therefore, admire and venerate men
like Reaumur, De Geer, Swammerdamm, Rösel, Bonnet, Huber,
Lyonet, Rengger, Carus, Treviranus, &c., whose multifarious endea-
vours and labours have acquired for us the knowledge which may be
considered as forming the foundation of our conclusions and future
deductions.

To observation, which is more subject to casual opportunity, we may
append experiment, as a second means of enlarging the compass of
physiological knowledge. Experiment is an observation produced
forcibly, and consequently not so fully to be depended upon as those
derived from secretly watching nature ; we must therefore be more
cautious in experimenting, for nature constrained frequently adopts a
form and figure which in a state of freedom she would despise. This
is, namely, still more the case in the lower animals, from their possess-
ing a greater power of adaptation to circumstances than the higher
ones ; I will merely refer to Trembley’s well-known experiments upon
the polypi, as well as to Spallanzani’s history of the reviviscence of the
wheel animal; which last, however, according to Ehrenberg’s recent
observations, are untrue. This has been also the case in insects ; for
who would not be incredulous upon being told that the larvae of a fly
( Eristalis tenax. Meig.) will admit of being pressed in a book-binder’s
press as broad and thin as a card without being killed, when freed from
its confinement and returned to its usual dwelling-place ?

§ 200.

Having learnt the way whereby physiological facts may be acquired,
we must look for a method according to which these facts may be
appropriately classed. If with this object we reflect upon all the
phenomena relating to the life of insects, we shall find a portion of
them refer particularly to the functions of the body, and another por-
tion develope higher, and, as it were, intellectual tendencies in insects.
To the first belong those observations which acquaint us with their

304

PHYSIOLOGY.

generation, nutrition, motion, and sensation ; to tlie other the care of
the parent for the offspring, the construction of their habitations, the
various localities of various groups, and the thence originating geogra-
phical distribution, and lastly, the influence insects exercise during
their lives upon nature generally, and especially upon man, and which
he, as if nature were created for him alone, distinguishes as the benefits
and injuries of the insect world. Each of these main divisions has its
several subdivisions. All observations, consequently, which belong to
somatic physiology can refer merely to the functions of the organic
system, and consequently they follow in the order of these four systems.
The subdivision of the second, or psychological physiology, or their
psychology, is more difficult, but a portion of their spiritual phenomena
may be more or less accurately arranged according to those organic
systems, and to which may be appended, lastly, the result of observa-
tions upon the influence of insects upon nature generally. This view
presents the following arrangement : —

I. Somatic physiology.

a. Origin and propagation of insects.

b. Nutriment and development of insects.

c. Motions of insects.

d. Sensual phenomena.

II. Psychological physiology, or psychology.

a. Sexual instinct.

b. Nutrimental instinct.

c. Dwelling-place — degrees of warmth and cold — geographical

distribution.

d. Benefits and injuries produced to man.

FIRST SUBSECTION.

SOMATIC PHYSIOLOGY.

§ 201.

The path pursued by somatic physiology in the development of its
contents is the same as that followed by nature in the development of
insects. We commence, therefore, with the first appearance of the

SOMATIC PHYSIOLOGY.

305

insect in nature, with its generation, which properly precedes its exist-
ence, in fact producing it. If the generation be effective, its whole subse-
quent life is mere development, and its first appearance is its develop-
ment in the egg. In the egg it first takes an independent existence,
and it requires but the most universal agents in nature, light, air, and
warmth, to raise its, as it were, preformed individuality to its perfect
individuality, and thus its life in the egg characterises the first act of
its existence as an insect. When the embryo period is closed, the
larva, more independent than before, takes its place in nature. Its
whole object is development, and this it attains by means of nutriment.
Growth is the consequence of its then excessive voracity ; its skin
becomes too narrow, it strips it off, and acquires a new one. This
moulting it repeats several times, until full grown, and it then first
feels that it has, as it were, overfed itself ; it therefore ceases, fasts some
days, again moults, and in a tolerably long period of continual sleep it
lives upon its own fat ; the intestinal canal consequently shrinks up,
and at its expense the organs of generation are developed. This period
may be compared with the stage of puberty in man and animals.
When, however, this last period of development is completed, the per-
fected insect makes its appearance in its full state of activity with
preponderating irritable and sensible organs. Motion and sensation
are its life, propagation its end, and to which its chief spiritual func-
tions are directed. The male seeks the female with restless fervour, the
latter allows itself to be found, and yields, and its spiritual life then
commences in its care about the depositing its eggs, in the structure of
its nest, and its anxiety for its young. The males do not at all par-
ticipate in these occupations, but become, as in the bees, turned forth
as unprofitable members of the community.

This therefore is the subject of our inquiry in the first subsection,
and its transit to the second, and their connexian together is also thus
exposed.

FIRST CHAPTER.

OF GENERATION.

§ 202.

Under generation, in its broadest sense, is understood the origin of
organic beings. The full application of the principle, that from
nothing nothing can be produced,” is here exemplified ; a foundation
must always pre-exist to produce a new organism. If this foundation
be the universally distributed organisable matter whence absolutely
lower organisms may be developed, it is called single generation
(generatio in cequalis ), or, also, equivocal generation ( generatio origin-
aria s. cequivoca). If, however, the foundation be another animated
body whence the new individual is developed through the active agency
of the old one, it is called double generation {generatio cequalis ), or pro-
pagation ( generatio propagativa). Propagation may be also of several
descriptions; for either a portion of the old individual is separated,
and becomes an independent being, which is called propagation by
shoots; or else in the body of the old individual the commencement of
a new one is developed, which germen having attained its maturity
quits the maternal sphere, and thus acquires an independent existence,
which is called propagation by germens ; or lastly, the development of
this germ can only succeed by the mother receiving, or even the germ itself
made competent to it by the intromission of, a peculiar exciting fluid.
This last and most limited mode of propagation is distinguished by the
character of sexual, and the active individual or active portion is called
male, and that upon which it acts, the passive part, or germ-forming
individual, the female. If these two faculties be united in one indivi-
dual, it is then called hermaphrodite.

These several relations are the abstract of all the phenomena cha-
racterised by the name of generation throughout nature. Indeed, some
exhibit modifications in their form, but they remain absolutely the
same : for example, the propagation by shoots, when, as in the Infusoria,
it presents itself as a separation in halves. Here the stem forms a
shoot, which costs it the half of its substance, whereas in the usual pro-

OF GENERATION.

307

pagation by shoots in the polypi, but a very small portion separates
from the stem. But we may first ask, do all these different modes of
propagation present themselves in insects? or, are there generalised
observations upon the origin of insects which exclude the one or the
other kind of propagation ? Are these observations sufficient to deduce
thence a general law, or do they admit of extension to but a very few
limited cases ? The investigation of these several questions will con-
stitute our first inquiry.

§ 203.

With respect to observations upon the equivocal generation of
insects, we possess many credible authorities which confirm it. The
best known phenomenon of this description is the Phthiriasis, or lousy
disease, in which a particular species of louse ( Pediculus tabescentium,
Alt.* ) originates upon the skin, and collects in great numbers at par-
ticular spots, chiefly upon the breast, the back, and the neck, between
folds of the skin, making the skin uneven, so that scale-shaped lappets
of the epidermis peel off, and beneath which the lice conceal them-
selves. We find in ancient, and here and there in modern authors,
testimonies of their spontaneous origin, the true cause whereof may
consist in a general corruption of the juices in old, weak, and enervated
subjects. Pheretima, according to Herodotus, and Antiochus Epi-
phanes, both Herodians, Sylla, Alcmanus, the Emperor Maximian, the
poet Ennius, the philosophers Pherecydes and Plato, Philip the Second,
and the poet and actor Iffland, are said to have died of it ; and very
recently, at Bonn, at the clinical school there, a woman of seventy was
found to be thus diseased, but was cured by the rubbing-in of the oil
of turpentine. Fournier t relates another instance of it in a cleanly lying-
in woman, who had much covered her head, and after suffering head-
ache for a fortnight, which totally deprived her of sleep and the desire
to eat, a great quantity of lice were found to have originated upon her.
A very similar case was observed by my esteemed tutor, P. Kruken -
berg, of Halle, in a young girl, who had received a wound in the head,
and which was communicated verbally to me. Also, where a pre-
disposition exists, the lice appear to be able to originate in the internal
cavities; at least, Fournier cites an observation of Marcheli’s, upon a

* Alt., Dissertation de Phthiriasi. Bonn. 1824, fig. 4. 4to.
f Diet. Medieale, Art. Phthiriasis.

x 2

308

PHYSIOLOGY.

woman who frequently suffered from the menstrual flux, in whom the
lice appeared in multitudes upon the skin, and indeed came out at her
ears and anus, after she had combed herself, as she said, with a, pro-
bably, dirty comb ; they were evacuated at the anus chiefly after
clysters, which were applied in consequence of anxiety, pain, and colic.
As in all these cases a decided transfer of lice probably did not take
place, although in the last the patient herself surmised it, we may
equally doubt it in children, the majority of whom, at a particular
period of their lives, are furnished with them. We know many
instances in which head lice are found in the cleanly children of
opulent parents who associated merely with their equals, who were
likewise kept very clean ; and it appears that, as in childhood, the
general constitution of the body favours the origin of lice, the same
effect is produced in adults by uncleanliness. In Poland and Russia
the body louse ( Pediculus vestimenti, Fab.) is so common that the lower
classes are seldom found there without them ; to which we may add,
the general distribution of lice among warm-blooded animals, almost
each of which has its peculiar louse, indeed many harbour several
species of parasites, which approach very closely to the true lice. But
that these latter may be with facility conveyed from one individual to
another is likewise certain, and it is thus that the distribution of lice
takes place in many young animals and children ; and in these they
increase the more rapidly, from the predisposition already existing in
young and juicy bodies. Whereas the true Phthiriasis , which presumes a
very morbid state of the juices, is not contagious, as was proved by the
case at Bonn, for the woman had, for a fortnight previously, slept in
the same bed with her husband, who remained perfectly free from the
lice. But the body louse, which is rather the parasite of healthy but
dirty people, may be conveyed from one individual to another, yet with
a little precaution it is easily removed. This, however, is not the case
in the louse of the Phthiriasis , for in some of the preceding cases the
greatest cleanliness effected nothing, new lice were produced, and their
propagation did not cease until the sufferer dwindled to death.

Whether all the preceding cases were absolutely Phthiriasis remains
uncertain, for in some indeed we are sure that it was not lice, but Acari,
which were the destructive creatures. Thus Aristotle * relates of
Alcmanus and Pherecydes, that the lice were formed in pustulous swell-

Hist. Anim., Lib. v. cap. 31.

OF GENERATION.

309

ings, out of which they came when opened. These creatures were
doubtlessly no lice, but Acarince , for wherever insects have been found
in pustules or vesicles beneath the epidermis, they belonged to this
family, and not to the true lice. Many instances of this kind occur,
and are generally known, at least to physicians $ for such are the Acari
of the itch ( Sarcoptis scabiei , and Acarus exulcer ans) , which are
found in the immature pustules of that disease, and which will produce
it in healthy individuals when placed upon them. But as we exclude
the Acari from the class of insects, we can take no further notice of
those several cases nor of the species producing them ; we consequently
refer to the article Acarina and Acarus in the Allgem. Encyclopedic
of Ersch and Gruber, tom i., which are written by Nitzsch, doubt-
lessly ihe best acquainted of anybody with parasitic insects and the
Arachnidce.

The Acari stand in the same degree of relation to the Arachnidce
that the lice do to insects, and consequently the similar mode of living
of both families will not strike us as strange, but rather demonstra-
tively ; if the one originate spontaneously, so will the other : of the
Acari it is certain, and consequently also of the lice, even although
direct observations are wanting.

But we may ask. Whence originates the first louse in Phthiriasis ?
Does it proceed from the skin as a deus ex machina ? or are certain
parts of man developed to insects ? or are they formed from substances
merely deposited upon the skin ?

With respect to the first opinion, it admits neither of being compre-
hended nor supported by argument, and must therefore be wholly
rejected. For the transformation of lappets of the skin into lice, we
might cite as analogous the supposed transformation of intestinal flocks
into intestinal worms; but these have at least vessels, and participate
in the vitality of the organism, which, in the dead lappets of the skin
which peel off, is no longer the case, for it is impossible that such
should be transformed to living beings ; therefore the third is the only
tenable opinion, and this we adopt. From the perspiration which accu-
mulates chiefly at the above-named parts of the body, namely, at the head,
neck, breast, along the back, beneath the arm-pits, and the softer parts,
the germs of new organisms are developed in such individuals whose
secretions have a strong tendency to corruption, and this is precisely
the case in children and diseased individuals. These germs can pro-

310

PHYSIOLOGY.

duce only such organisms that are adapted to the organ upon which
the germ has formed itself. For the skin these are parasitic insects, and
consequently only such, viz. lice, can be produced ; beneath the skin,
however, the parasitic arachnidse ( Acarince ) originate precisely in the
same manner. In the pustules of the itch they are developed only so long
as they themselves are forming, and therefore containing lymph. We
may therefore consider that it is from this lymph that their germs are
developed; subsequently, however, when the material producing the germ
is exhausted, the lymph itself corrupts, and becomes pus. Precisely
the same takes place in the Endozoa . Von Bar has observed this deve-
lopment in the remarkable Bucephalus , and it is as good as proved in
many others ; why should not therefore the skin, which has precisely the
same structure as the mucous membrane of the intestinal canal, give
rise also to parasites peculiar to it ? I know nothing that satisfactorily
opposes the adoption of it. Equivocal generation consequently takes place
in the lowest insects : they can originate from it, and do so frequently.

§ 204.

The second kind of propagation, that by shoots, has not yet been
observed in insects ; it is also perfectly contradictory to the idea of
creatures so highly organised they are. Some observations, however,
seem to confirm the possible development of insects from germens or
eggs laid by an unimpregnated female. We will here communicate
these instances.

All observations hitherto made upon this subject may be divided
into two groups, the one of which seems to prove that this mode of
propagation constantly and regularly takes place in certain genera, and
the other that it occurs but occasionally, and as exceptions. As a
regular mode of propagation, it is ascribed to the Aphides , or plant lice.
These produce throughout the whole summer living female young ones,
which again, without any preceding impregnation, according to the obser-
vations of De Geer and Bonnet, also produce living female young ones.
This spontaneous development is repeated to the tenth generation, and
indeed still further, if, as Kyber has proved by experiment, the plant
lice with the plants they inhabit be removed into heated rooms to pass
the winter. Treated thus, Kyber observed a colony of Aphis Dianthi
continue to propagate for four years without the single impregnation of
a female by a male, but they continued to produce young ones which

OF GENERATION.

311

were all of the female sex* * * *. But, according to Bonnet f and De Geer,
male individuals appear in August, upon the decrease of the tempera-
ture, which then copulate with the females, whereupon the females lay
eggs, from which, in the ensuing spring, young female Aphides are
brought forth, which re-produce female individuals until the autumn,
without they or their young having had any intercourse with the other
sex. Bonnet X even considered that the eggs of the females was but
a procrastinated development of the young produced by cold, and this
supposition is confirmed by Kyber’s observations, who found them
never to lay eggs when removed to warmed apartments.

These facts, which, after the repeated observations and experiments
of Bonnet, De Geer, Reaumur, and Kyber, may be considered as incon-
trovertible, perfectly prove the possibility of a spontaneous develop-
ment ; at least the opinion of some naturalists, that the impregna-
tion of the great grandmother extends to the tenth generation, is
much more incomprehensible than the other. A second instance is
furnished, according to former general assertion, by the genus Psyche ,
Latr., which contains the cased caterpillars. Reaumur § was probably
the first who made the observation that the female, which he mistook
for a caterpillar, because it was apterous, laid eggs without a male
having been near her. SchifFermiiller subsequently observed the
same ||, as well as Pallas % who described the species upon which he
made his observations as Phaltznci xylophthorum. Stimulated pro-
bably by these communications, Rossi undertook numerous experiments
upon this obscure mode of propagation of the cased caterpillars, which,
according to Ochsenheimer ** * * §§, “ were conducted with the greatest care,”
and yet produced the same results. Other witnesses were found in
Bernoulli +f, who, among other instances of the kind, mentions one of
a cased caterpillar, in Kühner JJ and Schrank §§. Nevertheless Zinken,
gen. Sommer has proved, by a long series of observations, that in these,

* Germar’s Mag. der Entom., vol. i. part ii. p.14. + Insectologie, tom. i.

Contemplations de la Nature, tom. i.

§ Memoires, edit, in 8vo, tom. iii. part i. p. 1.94.

|| Verzerchniss der Schmet. der Wiener Gegend. 4to, 1766, p. 288.

Nova Acta, tom. iii. (1767) p. 430.

** Schmetterlinge von Europa, vol. iii. p. 178.

f f Mem. de l’Acad. Roy. de Berlin, 1772, p. 24.

Naturforscher, St. VII. (1780), p. 171.

§§ Fauna Boica, vol. ii. part ii. (1802), pp. 94 and 97.

312

PHYSIOLOGY.

as well as in all the other genera of Lepidoptera, the copulation of
the sexes and the impregnation of the female is regularly requisite to
the development of the eggs, but that it probably takes place whilst
the fully developed female still remains in the case spun for her pupa ;
at least he detected the escaped females in this situation, and saw them
placing their heads and sometimes their anus at the aperture of the
case.

But the other cases here and there observed as sporadical, and which
consequently belong to the second group, are not thereby contradicted.
That unimpregnated individuals lay eggs may be observed in the females
of all the Bombycidce, if, some days after their escape from the pupa case,
they be impaled and allowed to die slowly. The females of the Sphinges
do the same, but never the butterflies, according to Roesel’s observa-
tions, nor likewise the unimpregnated females of the Coleoptera, as
Suckow remarks *. Among the other orders I remember to have
observed only some Diptera, particularly the Tipulce, to lay eggs in
the convulsion of death ; for example, species of the genera Rhyphus,
Mycetophila, and Tachydromia. But from these eggs it is but rarely
that young are disclosed, and indeed only from some, and not from all
that are laid. The earliest instance on record is probably that related
by Albrecht f, next to which is that related by Pallas, and observed
by him in Euprepia casta , O. ( Bombyx casta, Fab.). An instance is
known of it in Gastrophaga potatoria , O. Bernoulli relates several
instances, one in Gastrophaga quercifolia, O. ( papillon paquet de
feuilles seches ), which his friend, Professor Basler, had seen. He
reared the caterpillar, it changed into a pupa, the imago came forth,
which after a short time laid eggs, from which young caterpillars came.
A second case Bernoulli himself observed in Episema cceruleocephala,
Tr. Lastly, L. C. Treviranus J has observed the same spontaneous
development in Sphinx Ligustri, Suckow §, in Gastrophaga Pini , O.,
and my friend. Dr. Al. V. Nordmann, recently in Smerinthus Bopali.
According to Lange || and Schirach % the queen bee will sometimes lay
unfruitful eggs without copulation with the drone, and indeed the females
produced by such eggs will again lay productive eggs without having

* In Heusinger’s Zeitschr., f. d. Org. Phys. vol. ii. p. 264.

t Miscell. Acad. Nat. Cur. an. 9 et 10. D. 3. obs. 11. p. 26.

+ Venn. Schrift, vol. iv. p. 106. § In Hcusinger, 263.

II Gemeinnützige Arbeiten der Sächsis, Bienengcsellsch, vol. i. part i. p. 39.

1f Ib. p. 155.

OF GENERATION.

313

copulated. Thus the Aphis has a companion in its great and highly
remarkable fertility.

§ 205.

In the same way as a spontaneous generation is found as an excep-
tion among insects do we find imperfect hermaphroditism among them.
Perfect hermaphrodites among animals are found only in the tape-
worms, the Trematodes, many Annulata (for example, the leech and
earth-worm), and the majority of the Mollusca . They possess male
and female organs, but never impregnate themselves (perhaps with the
exception of the tape-worms), but mutually. In insects, on the con-
trary, hermaphroditism is but one-sided, that is to say the one, gene-
rally left side, exhibits female forms and organs, and the opposite side
male organs. Among the numerous instances of this kind the majority* * * §,
indeed almost all, are found amongst the Lepidoptera, and thus this
order displays itself a second time as that which has the greatest
tendency to diverge from the regular sexuality of insects.

The earliest observations upon this subject were made known by
Schaffer in a separate treatise f. It was an hermaphrodite Liparis
dispar, O., the right side of which was male and the left female. Then
Scopoli J described an instance in Gastrophaga Pini : according to his
account, two caterpillars had enclosed themselves in one cocoon, and
changed into one pupa, which produced an hermaphrodite imago, of
which one larger side was female, and the other, smaller, had male
wings and more strongly pectinated antennae, at the anus there were
both sexual organs, which copulated, after which the female side laid
eggs, from which young caterpillars proceeded. Henceforward com-
munications of this kind became more numerous. Esper § next
described an hermaphrodite Gastrophaga Cratcegi, in which the right
side was male and the left was female ; then Hettlinger || a similar one of
Gastrophaga Quercus ; Capieux saw an hermaphrodite of Saturnia

* Consult Rudolphi über Zwitterbildung in the Abhandlungen der Königl. Academie
zu Berlin. Physkalischeiklasse, 1828, p. 50.

Der wunderbare und vielleicht in der natur noch nie erschienene Eulenzwitter.
Regensb. 1761, 4to.

X Introductio ad Hist. Nat. Prag, 1777, 8vo. p. 416.

§ Beobachtungen an einer neuentdeckten Zwittcrphaläne ( Bombyx Cratcegi). Erlangen,
1778, 4to. Schmetterlinge, vol. iii. p. 238. PI. XLV, f. 1 — 6.

|| Rozier, Obs. de Phys. tom. xxvi. p. 270.

Naturforscher St. xii. p. 72. PL II. f. 6

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PHYSIOLOGY.

Carpini, the left wing and antenna of which was male, but the right,
with the rest of the body, was female ; Ernst * * * § a reversed one, conse-
quently right male and left female hermaphrodite of Sphinx Convolvuli ;
Schrank f one of Vanessa Atalanta, in which all the parts of the
right side were smaller than those of the left.

After the preceding, Ochsenheimer sought £ to bring under one
view all the hermaphrodites which were already described, or which
he had himself seen, and partly possessed in his cabinet, and which we
shall here add, with the addition of such as have been since made
known.

He divides all hermaphrodites into two groups, namely, into perfect,
in which one side is perfectly female and the other male ; and into
imperfect ones, where the habit of one sex prevails throughout the
entire insect, and the forms of the other are perceptible in solitary
parts.

A. Perfect Hermaphrodites.

Papilio Polycaon. Dixon, Secretary to the Linnaean Society, sent
an hermaphrodite to MacLeay, which on the right side was male, and
P. Polycaon, F. and the left female, and P. Laodocus, F. Thus the
identity of this species is proved §.

Argynnis Paphia. Right male, left female, antennae the same, the
under side agreeing with both sexes, the abdomen having on the right
side an anal tuft. Ochs.

Lyccena Alexis. Antennae alike, wings on the right side female,
with a faint blue iridescence within the inner margin of the posterior
wings ; left side male. The under side as in both sexes, abdomen
female, above bluish. Ochs.

Lycoena Adonis. Left male, right female, male wings and antennae
larger, palpi also dissimilar, the left somewhat larger. The abdomen
on the right side thicker, more bellied, the left dried up, bent inwards
upon the right side, distended exteriorly. In the Royal Museum at
Berlin.

Vanessa Atalanta. Left male, right female ; abdomen chiefly
female, but on the left male side more dried up (indicating the pre-

* Papillons d’Europe, tom. iii. p. 123. PI. CXXII. n. 114.

f Fauna Boica, vol. ii. part i. p. 192.

£ Naturgeschichte der Schmetterlinge von Europa, tom. iv. p. 185, &c.

§ Trans, of the Linnaean Soc,, tom. xiv.p. 584.

OF GENERATION.

315

senee of the right ovarium. Described by Germar, and caught near
Dresden *.

V anessa Antiopa. Right male, left female, the right antennae con-
siderably the shortest ; abdomen as in the preceding. Bred from the
caterpillar at Halle, and described by Germar +.

Deilephila Euphorbia, O. Left male, with smaller wings, right
female ; body distinctly divided in the centre, left green, as in the
male, right reddish ; palpi and legs white ; abdomen female. Described
by Germar J.

Saturnia Pyri. Right male, left female ; abdomen more elegant
than in the female, at its end, the organs of both sexes quite perfect, and
distinctly close together. Ochsenheimer.

Saturnia Carpini. Left male, right female ; abdomen female, with
merely female organs. Ochsenheimer. Another instance in the Royal
Museum at Berlin: smaller than usual, right antennm and wings
female, left male ; body of the form of the male, but coloured like the
female ; a distinct separation not observable. Rudolph i, as above.

Endromis versicolora. Right male, left female ; abdomen female,
but upon the right side coloured as in the male. Ochs.

Lipar is dispar. Right male, left female; back with a distinct central
line of separation ; abdomen smaller than in the female, but with female
anal tufts and male organs. Rudolphi. Ochsenheimer describes a
second instance, but the left side was male, the right female ; abdomen
smaller, particularly thinner than in the female, with large anal tufts.

Harpya vinula , O. Right male, left and the abdomen female ; both
sexual organs. Ochsenheimer.

Gastrophaga quercifolia. Left male, right female ; distinct line of
separation throughout the whole body, both sexual organs. Upon its
anatomical inspection an ovarium was found upon its right side, the
oviduct of which opened into the vasa deferentia about two inches before
its termination, and that of the spermatheca, which hung attached to
the common evacuating duct. Upon the left side there were two testes
behind each other, which were connected by a thin vessel, one spermatic
duct passed from the second testicle, and immediately received, as in
all the Lepidoptera, the spiral vessel ; further beyond, on the opposite
side, was found a second vessel, which opened into it, probably the

* Meckel’s Archiv, fur Physiologic, 1819, tom. v. p. 365 — 8.
f Ibid. X Ahreu’s Fauna Insect. Europ., fase. i. PI. XX.

316

PHYSIOLOGY.

rudimental sperm duct of the second testicle, and the sperm duct now
distended into a common evacuating duct, to which the spermatheca of
the female was attached ; it thence passed into the sheath of the penis.
Rudolphi.

Gastrophaga medicaginis. Right male, left female; abdomen
female, but more compact. The separation of the sexual organs merely
indicated. Rudolphi.

Lucanus cervus. Left male, right female. Klug. *

Besides this remarkable hermaphrodite but one other instance of it
is known in the Coleopter a, mMelolontha vulgaris , in which, according
to Germar f, an individual has a male antenna on one side and female
on the other.

B. Imperfect Hermaphrodites.

Melitoea Phoebe. Male : the right antenna and the wing of the
same side larger, but agreeing with the left in colour and markings.
Germar.

M. Dydimus, O. Male : the left eye, the left palpus, and an-
tenna smaller ; the latter annulated with white, yellow at the apex,
the right of one colour ; wings equal, male ; abdomen male, but some-
what thick, the left sexual fang smaller. Upon its dissection the male
sexual organs were found, and a free ovary upon the left side united to
no other organ. Klug. J and Rudolphi.

Pontia Daplidice. Female : the right anterior wing male, antennae
and palpi equal, sexual organs resembling the male. Rudolphi.

P. cardamines. Two instances: one a male, whose right superior
wing has female markings ; and a female with some male colours. Ochs.

Deilephila galii, O. Female; left antenna and palpus smaller,
but agreeing with the right female one in colour and markings.
Germar.

Saturnia Carpini, O. Female: antennae male, superior wings
formed as in the male, but coloured as in the female ; posterior wings
female, the left with a reddish brown spot. Ochs.

Liparis dispar, O. The males have frequently white colours ; but
there are two positive instances, 1st, a male, of which the abdomen and
the right posterior wing is female ; and 2nd, an individual in Mazzola’s
collection. The right antenna is male, the left female ; the abdomen

* Schriften der Gesellsch Naturf. Freunde zu Berlin.

i* Meckel’s Archiv, vol. 5. p. 366. $ In Froriep’s Notizen, vol. x. p. 183.

OF GENERATION.

317

narrow, but more feminine, of a yellow grey, with dark brown anal
tuft ; superior wings whitish, on each side dissimilarly mixed with
brown ; the right posterior wing coloured chiefly as in the male, the
left as in the female. Ochs.

Gastropliciga quercus. Two individuals : 1 st, body and antennas
female, as well as the left wings, the right male ; 2nd, body and right
side female, the left male; both antennae brown, and pectinated.
Ochsenh.

Gastrophaga castrensis, O. Male, but having all its parts tending
to the female form ; right a female, left a male antenna, also on the
left side distinct female wings, whereas the right are entirely male, only
somewhat larger than in male insects, and the colours brighter than in
the female. In the Royal Museum at Berlin. Rudolphi.

If we now cast a critical glance at these instances of hermaphro-
dite structure we shall speedily recognise that all of them may be more
correctly brought into the class of monstrosities. True natural her-
maphroditism exhibits perfect female in conjunction with perfect male
organs, and the external appearance of the animal is neither male nor
female, but an intimate mixture of both, a really new form. But this
in insects is never the case. One sex here is developed at the expense of
the other, and the more equal their mutual development, the more
heterogeneous is the appearance of the individual in its two halves.
The perfectly equal development of both sexual organs may be sup-
posed only in those cases in which the one half appears entirely male
and the other wholly female ; in all other instances one sex will pre-
dominate, to which the other is merely associated. This was the cha-
racter of both those instances which were subjected to anatomical
inspection ; both were properly males, which, besides their testes, pos-
sessed an ovary. This is still more the case in the so-called imperfect
hermaphrodites, for in them the preponderance of one sex is evinced
externally. A question which still awaits an answer is — which side is
in general male, the right or the left ? and why is this male, and the
other female ? That we may answer this question we must group the
observed instances, and we then And that in by far the majority of the
true hermaphrodites (in fourteen of the cited instances) the right is
male and the left female, and that seldomer far the right side is found
to be females and the left male (in nine instances). Among the imper-
fect hermaphrodites, on the contrary, the majority (six) were female,
and the minority (five) male with female characters : we may here

318

PHYSIOLOGY.

remark, that the preponderating sex takes the right side, and that
associated to it the left. This appears to harmonise with the prepon-
derating plastic nature and energy of the right side in general, and to
proceed from the same fundamental law.

Another question is — do such hermaphrodites suffice to themselves ?
The observation of Scopoli speaks in favour of it, but all other, and
even regular hermaphrodite organisms speak against it. The her-
maphrodite Mollusca never impregnate themselves, but mutually ; con-
sequently, how should imperfect hermaphrodites be able to impregnate
themselves ? Even this self-impregnation appears to be mechanically
impossible, as the penis and the vulva are enclosed by valve-shaped
organs, and by this means separated from each other. If, therefore,
Scopoli’s pine Bombyx really laid eggs, it did so like all the female
Bombyces , namely, in the anguish of death ; and if caterpillars were
developed from these eggs, this development must have occurred as
independently as the abovementioned instances of spontaneous deve*
lopment, an assertion which is rendered the more probable, as here, by
the presence of the male organs to a certain extent, a subjective female
sexuality already existed.

§ 206.

As we have now shown that the several kinds of generation, except-
ing the sexual by means of separate sexes, are irregular, and having
proved that the observed instances are mere exceptions, it remains for
us to notice this last mode of propagation, as that which is regular and
general. We may therefore adopt that all insects are of separate
sexes, and that they require the intermixture of both sexes to be
fruitful. Experience confirms this doctrine. Indeed, in some families,
as in the bees and ants, there are sexless individuals, which can operate
neither masculinely nor femininely, and therefore never copulate ; but
observation proves that such individuals are merely abortive females,
and that in these families the female functions are divided between
two different beings, the one of which copulates and lays eggs, and the
other attends to the nurture of the offspring. If we therefore more
closely investigat e sexual generation by means of separated sexes, as
found among insects, our first object of inquiry will be the differences
of both sexes ; which is succeeded by their union for propagation or
copulation, the consequence of which is impregnation, and thence fol-
lows the formation of the egg and the development of the embryo. A

OF GENERATION.

319

few divarications from the usual course will be appended, and we now
proceed with the subject.

With respect to the differences of the sexes, their whole character
may be thus distinguished, viz., that the male displays itself by the
preponderance of evolution and the female by the predominance of
involution. This difference is expressed as forcibly throughout the
whole corporeal structure, as in the individual organs, so that in general
the mere view of an individual will determine its sex ; but it carries
greater conviction to inspect the sexual organs, the differences of which
we have fully shown above (§ 142 and 152). Independent of this
character expressed in the structure of the entire body, we find in many
insects, particularly those of the male sex, peculiar organs restricted
to one sex only, and which likewise indicate the sexual character.
Whence it is sometimes difficult, as well on account of the frequently
vast discrepancy of form, and even more of colour, and chiefly in exotic
insects, which we have not observed alive, to bring together the sexes
of a species, and recently only, since the vast increase of species has
proved the necessity of their reduction, greater attention has been paid
to sexual differences ; and von Malinowsky * and Klug + in particular
have earned well-merited praise for separate treatises upon this
subject.

If we more closely inspect these sexual differences in the several
orders, we find, to begin with the Coleopter a, the above mentioned
characteristic everywhere expressed. The body of the female is always
thicker, larger, more succinct, frequently more convex ; that of the
male, on the contrary, more slender, smaller, more delicately formed,
and furnished with longer limbs. Besides these general differences, the
several families exhibit peculiar characters. In all male Cicindelce ,
Carabodea, Dylici, the males have distended anterior tarsi. The
number of these distended joints varies in the several families and
genera. In Cicindela the three first joints only of the anterior legs
are distended. In the Carabodea an increasing number is found in
the distension of the tarsi ; in many genera, for example, Agra and
other exotic ones, the tarsi of all the six legs are distended ; in others,
for example, Harpalus and its affinities, the tarsi of the four anterior
ones ; in others again, for example, Carabus and its affinities, as well

* Neue Schriften der Hailisch. Naturf. Gesellsch. vol.i. PI. VI.

f Magaz. dev Gesellsch. Naturf. Freunde zu Berlin, 1807, p. 65, and 1808. p. 48.

320

PHYSIOLOGY.

as Arnara, the Zabrodea, Feronice, and many others, merely those of
the anterior pair. Each of these groups exhibit new differences,
according to the number of the distended tarsal joints. We thus find
in the third group, in which the anterior legs only have distended
tarsi, sometimes four distended joints, as in Elaphrus, JBlethisa, &c. ;
sometimes only the three first, as in Chlcenius, Amara, Feronia, &c. ;
sometimes the two first, as in Patrobus ; and lastly, the first alone, as
in Omophera, Latr. In addition to these differences, we observe in
the males of Harpalus, the Amarodea, Peecili, and the entire genus
Feronia, a brighter reflection upon the elytra ; whereas those of the
female are duller, sometimes indeed, for example, Feronia ( Abax )
striola , almost opaque. The same character is also found in the
majority of the water beetles, and which has sometimes occasioned, as
in Hydroporus parallelogrammus, Ahr., the separation of the male
and female as two species ; for Kunze described the male of this species,
which Ahrens had described from a female specimen as Hydroporus
consobrinus *. The same is the case with Hydrop. picipes, Kunz. f >
and Hydrop. alternaus, Grav. ; the former is the male, the latter the
female, as specimens taken in copuld prove. The differences of the
structure of the tarsi is tolerably analogous in both families ; thus the
males of the true Dytici (for example, D. latissimus, dimidiatus, punc-
tulatus, &c.) have three distended tarsal joints on the anterior leg; they
are also distinguished from their females by having smooth elytra,
whereas in the latter sex the upper half is in general deeply furrowed ;
in Cybister ( Dytici Roeselii, Auctor.), on the contrary, the first pair
only has distended platter-shaped joints, and the female has no fur-
rows, but merely dull, scratched elytra. In Colymbetes the distended
tarsal joints do not form, as in the two other instances, a round patella
beset beneath with sucking cups, but they are long and extended, and

* Neue Schrift, d. Hallisch. Naturf. Gesellsch, vol. ii. part iv. p. 61, 2. We may here
remark, en passant , that the following is the synonymy of this species : —

Hydroporus parallelogrammus. Ahr., Nov. Act. Nalens, vol. ii. fas. ii. p. 1 1. 1 .

$ Hydr. consobrinus. Kunz., ib. fas. iv. p. 61. 2.

Hyph. nigrolineatus. Schönh. Syn. Ins.

$ Hydr. nigrolineatus. Kunz., ib. p. 61. 1.

Hyph. parallelogrammus. Gyll.,Ins. Sues., tom. iv. p. 389. 13 — 14.

Hyph. nigrolineatus . Gyll. Ins. Sues., tom. iii. add. p. 688.

Dyticus lineatus. Marsh., Entom. Britt, i. 426. 35.

f Ibid, 61. 2.

OF GENERATION.

321

more resemble the feet of the Carabodea ; it is the same in the other
genera, with the exception of Cnemidotus, the anterior tarsi of the
male of which are not at all distended. In the predaceous beetles, or
S taphylini, the distended feet are found only in one sex, yet in other
instances the female also, as in Aleochara , has very broad feet. In
many of the Steni also some of them only are distended. To these may
be added other sexual differences, viz., an arched excision at the ventral
plate of the last abdominal segment in the male, which is shown very
distinctly in Staph, laminatus. The male of Staph, hirtus, on the
contrary, has, according to Malinowsky, a strong shovel-shaped ap-
pendage at its thigh, which runs almost parallel with it. In Tacky-
poms rufipes the excision of the ventral plate is so deep that it has
the appearance of being bilobate, and in Latkrobium that plate is
thereby formed into a central carina, which is continued also in the
preceding ones. Similar excisions are said to be found also in the
males of the genus Stenus. The Peltodea exhibit but slight sexual
differences ; in Silpha four joints of the four anterior tarsi are dis-
tended ; in Necrophorus the same joints, but only the anterior pair.
Among the Dermestodea the male of Dermestes exhibits small hairy
warts upon the ventral plates of the last abdominal segments ; in Atta-
genus and Megatoma the last palpal joint of the male is long, thin, and
conical, in the female smaller, thicker, shorter, and ovate. In the large
family of the Lamellicornia sexual differences are very numerous, but
all confirm the above law of the predominating evolution of the male.
Thus, for example, the male Lucani have long mandibles, resembling
the antlers of stags, and much longer anterior legs, a larger head sur-
rounded by ridges, but a proportionately shorter body. In Geotrupes ,
Dynastes, Oryctes, and some true Scarabcei (for example. Typhous),
the males have large projecting horns, which proceed from the clypeus
and pronotum, and which are but slightly indicated in the female; the
same is exhibited in the scatophagous genera Copris, Phanceus, Ontho -
phagus, and besides the males of Phanceus and Ateuchus want the ante-
rior tarsi, instead of which they have a short hook, that retains the
female during copulation. In Cetonia the females have convex ventral
plates ; the males, on the contrary, excised ones, and which are pro-
vided in the centre with a longitudinal impression. The Melolon -
thodea exhibit sexual differences in their antennae: in Melolontha
itself the lamellae of the male are more numerous, and longer, and in
the female shorter, and fewer. In Rutela, Hoplia, and Anisoplia
the males have longer tarsi and stronger claws; in Melolontha longi -

322

PHYSIOLOGY.

mana. Fab., the male has immensely long anterior legs, in the more
robust female they are at least one-third shorter. In the genus Goliath
the clypeus of the male projects beyond the mouth in two bent pro-
cesses, which are wanting in the female. The male Aphodii have also
small pointed teeth upon their vertex, which are merely indicated in
the female, and among their affinities the Palpicornia, the male Hydro -
philus displays the last joints of its anterior tarsus distended interiorly
into a triangular lobe. In Bupresiis the male has again an arched
excision in its last ventral plate ; in the Platers the more slender males
have longer, strongly pectinated antennae, particularly the genus Cte-
nicera, Latr. Similar differences are exhibited by many Cantharides
( Telephori , Latr.), Anobia, as well as the genera Ptilinus and Dor-
catoma ; and very decided differences are exhibited in the male
winged Lampyri, the remarkable genus Symbius *, and some others (for
example, Drilus ), whose females have no wings. But the predomi-
nating evolution of the males is most distinctly displayed in the Capri-
corns, in which the constantly more slender males have much longer,
frequently double as long, antennae, which in the genera Steno -
chorus and Trachyderes have one joint more, viz., twelve joints,
whereas the female has but eleven. In Psygmatocerus , Perty, ( Phce -
nicocerus , Latr.), the male has fan-shaped antennae, whereas those of
the female are simple and filiform. Among the Curculios the males
have frequently longer snouts and antennae, as in Anthribus , Brenius ,
and Balaninus.

This law receives further confirmation in the other orders besides
the Coleoptera, for example, in the Hymenoptera. In Pteronus, Jur.
( [Lophyrus , Latr.) the male has doubly pectinated antennae, which in
the female are serrate only upon one side. In the Ichneumons the
antennae of the males are longer, finer, and porrect, those of the female
shorter, thicker, and, after death, spirally convoluted ; in many species
also they have a white ring, whereas those of the male are uniformly
black or brown. In all the aculeate Hymenoptera the male has
thirteen joints to the antennae, the female but twelve, and the former
also seven abdominal segments, and the female but six. Besides which
we find another important circumstance, namely, the deficiency of wings
in the female, whereas the males are winged, for example, in Tengyra,
Latr., the female of which is the apterous Methoca ; the same is the
case in Myrmosa and Mutilla. We find a similar difference in many

* Sundeval in Oken’s Isis, 1830. No. 12.

OF GENERATION.

323

LepidojAera, for instance, in some of the Geometers ( brumata ,
namely, and many others), and in the genus Psyche , Latr. The
males of the Bombyces and Geometers have doubly pectinated antennae,
whereas those of the female are much less strongly so, or merely simple
and setiform. The male Sphinges have longer narrower wings and
thinner bodies, the females have shorter broader wings and thicker
bodies.

Among the Orthoptera , in Blatta also we detect a deficiency of wings
in the female, exclusive of which, in this order, the females are readily
distinguished by their projecting ovipositor, and many males have
differently formed wings, for example, the Locustce, in which, at the
base of the wing, there is a clear hyaline spot, which has been considered
as the vocal organ.

The Dictyotoptera and Neuroptera exhibit in general no other differ-
ences but those derived from the sexual organs, in the Eibellulce, only,
the males have stronger and larger anal fangs than the females ; besides
which, in the genus Agrion, the sexes differ considerably in colour,
the brighter colours are peculiar to the males, and the darker bronzy
ones to the females. In Boreus , Latr., a genus very nearly related to
Panorpa, to which the Panorpa hiemalis, Lin., ( Gryllus proboscideus,
Pz. Faun. Germ. XXII. 18.) belongs, the male has small hook-
shaped wings, but the female, which is furnished with an ovipositor,
is apterous.

The sexual differences of the Diptera correspond in many instances
with those of the preceding orders. In the Culices the males have
long, very hairy, plumose antennae, and sometimes, as in Culex and
Anopheles, very long, clavate palpi, of the same length as the proboscis.
Among the Tipulrz the genera Erioptera and Ctenophora exhibit in
the male strongly pectinated ramose antennae, and much longer and
more delicate legs than the females. In Nematocera , Meig., ( Hexn -
toma, Latr.) the male antennae are twice as long as the female. Among
the Syrphodea the larger approximate eyes form a distinct male cha-
racter ; and in some instances they have also, as in Xylota and Helo-
philus, thicker posterior femorae than the female, a character peculiar
also to some male Empis. Occasionally also, as in the genera Hilara
and Dolichopus , the males have distended tarsi upon either their
anterior or intermediate legs.

The Hemiptera , lastly, exhibit striking and sometimes peculiar
sexual differences, among which the most remarkable is the vocal organ

y 2

324

PHYSIOLOGY.

of the male Cicada ( Tettigonia , Fab.). In other genera the male is
horned^ and the female is either wholly unarmed, or its horns are at
least much smaller. But the most striking is the sexual difference in
Coccus. In this genus the female has the appearance of either a thick
conical or flat scale-shaped spot, upon which no external organs are
perceived, or at most but the short stumps of feet upon the ventral
side. The males, on the contrary, are winged ; they have long dis-
tinct antennae and visible legs, but their body is much smaller than
that of the female, and in some cases, as in Coccus Adonidis, it is
scarcely from the fourth to the eighth part of the size of that of the
female. The females, from the abortion of their limbs, have scarcely
any motion, whereas the males are exceedingly active, and conse-
quently less frequently observed.

The differences of colour in the two sexes are in harmony also with,
and corroborate the assertion of the predominant evolution and involu-
tion. The males have brighter, more beautiful, and glittering colours,
whereas those of the females are darker, duller, and paler ; or when the
colours of the female are brighter than those of the male, for example,
in the crepuscular moths and Noctuce , at least the markings of the
males are much more distinct, sharper, and clearer. Among the Cole-
optera , Harpalus, Amara, and Feronia confirm these observations. Other
instances are shown in Tillus elongatus, the prothorax of which is red,
whereas the female, or Tillus ambulans , Fab., is entirely black. Some
Hymenoptera however form an exception to this rule, for example, the
genus Lophyrus, to whose black males we find associated variegated red
and brown or yellow and black spotted females ; just so in the genera
Tengyra and Myrmosa , their males are uniformly black and the
females partially red. Also in the Scolice, the females have generally
brighter markings than the males, for example, Scolia hortorum , in
which the head of the female is of a reddish yellow ; Fabricius conse-
quently considered it a distinct species, and called it Sc. flavifi'ons.
In Tiphia femorata also the male is entirely black, whereas the female
has red posterior femorae. But among the butterflies this law receives
full confirmation. Many exotic exceedingly splendidly marked males
have dirty- coloured insignificant females, for example, the beautiful
Papilio Priamus , the female of which is Pap. Panthous; as also Pap.
Helena is the male and Pap. Amphimedon the female of one species ;
the same as Pap. Amphrisius is the male, and Pap. Astenous the female.
The Pap. Ereclitheus male, and Pap. JEgeus female, described by

OE GENERATION.

325

Donovan, may be one species. In all these instances the male is darker
coloured and more brightly marked, whereas the markings of the female
are dirty and confused. In the extensive genus of blues ( Lycaznoe ) the
upper side of the males are almost all of a beautiful sky-blue, and the
females brown ; or the former are bright yellow-brown and the latter
of a dark brown. In the large Bombyces, in the genus Attacus, for
example, the markings of the male are much more decided, brighter,
and distinct, whereas the colour and markings of the fe males are con-
fluent. The same is the case in the Geometers. In the other orders
we find a similar relation, particularly in the above mentioned Coccus ,
in which the small males have frequently beautiful markings upon their
wings, whereas the females are uniformly brown-grey, or at least
always darker. In all these sexual differences insects are paralleled by
the birds. We here also in general find larger females, but the males
are invariably more beautifully marked, have longer wings, longer
crests, and spurs, which are wanting in the female. This, conse-
quently, still further confirms the analogies of both classes pointed out
above.

§ 207.

The act which precedes impregnation, and consists in the sexual
union, is called copulation (copula). We shall consider it in the order
of its time, place, duration, and particular relations.

As insects are preeminently animals of light, consequently the most im-
portant occupation of their lives (namely, copulation,) takes place in the
light, that is, by day. This we find confirmed in all true diurnal insects.
The butterflies copulate about noon, in the brightest sunshine. When
the female has placed itself upon a flower or a leaf the male flies to her
and flutters around her in a caressing manner ; if agreeable to his caresses
she indicates it by a gentle pulsation of her wings, and raising her
abdomen upwards the male flies down, and copulation ensues. The com-
mon domestic fly copulates constantly in windows in the sun, the male
ascending the body of the female, and instantly quitting it each flies off,
resuming its preceding business. Bees, which live solitarily and in pairs,
are frequently’found copulating upon flowers which the female has visited
in her industrious and laborious pursuit, and even without any cessation
of her labours, and just as speedily as each accomplishes its amorous
desires does their love cease; they then avoid each other as before, and
the female continues, but perhaps more zealously, her preceding occu-

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PHYSIOLOGY.

pations. But females are not always so agreeable ; many violently
resist and maintain their independence in a severe contest, in which in
general the males are subdued. The Asili, which alight upon leaves
and the glowing sand to sun themselves, are frequently disturbed from
this tranquillity by the arduous male, but they do not generally yield,
for they defend their innocence as valiantly as successfully. The
LibellulcB also do not copulate flying, but sitting (§ 152) ; the male, in
these, attacks the reposing female, who yields not until the sexual
instinct is fully developed, previously to which she takes wing and
escapes ; but their union in flight, on the contrary, although indeed
an expression of love, and reciprocal, is certainly no copulation.

Other insects, which are more truly crepuscular and nocturnal,
copulate merely at those times. The Bombyces sit immoveably
during the whole day, and during even the brightest sunshine they
do not yield to the developed sexual impulse. The males, however,
are more impetuous ; they swarm about the female even at improper
times ; for example, Liparis dispar , at noon, and when the sun is
hottest, but yet without finding her propitious to their suit. But so
soon as evening approaches, the female also arouses from her slumber,
and twilight, which increases the susceptibility of all sensible beings,
acts likewise influentially upon the Noctuce and crepuscular moths.
They are now urgent in their endeavours to approach the female, who
does not, however, play the prude, but is regardful of the favourite,
and yields to his solicitation. But, at this period, they are entirely
absorbed in each other; all activity and motion cease during copulation.
They sit apparently lifeless beside each other, with withdrawn antennae,
and limbs solely occupied with the business in hand, which, at least
for the male, is the last he will pursue : they, therefore, enjoy it as long
as possible ; indeed, the latter frequently falls down lifeless when the
female frees herself from him. This phenomenon can be observed daily,
during the summer, in the common Liparis dispar, Salicis, and in others
of the Bombyces. Towards evening their connexion commences, and
it is still continued on the following morning, but it is not rarely that
the male is already dead, or, at least, so exhausted, that it may be more
classed with the dead than with the living.

The Coleoptera also appear to copulate more towards evening. This
is well known in the cockchafer, which only about dusk acquires its
full vivacity. The same is the case with the dung beetle and stag
beetle. We, indeed, frequently find them thus occupied during the

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327

day, but, in general, it commences in the evening. Some, as, for ex-
ample, the Carabodea, we seldom detect in this situation, whence I
conclude, that they copulate in the evening, and that it is speedily over :
some are certainly nocturnal animals, for example, Calosoma sycophanta
and the large Procerus scabrosus.

The place they select for the purpose also greatly varies, but the
majority seem to prefer the air to their other usual places of resort.
Some copulate in flight, as the gnats, Ephemer ce, and ants ; others select
the moment that the female reposes : they then approach her, and fly
off in connexion with her, and generally borne by her. Thus is it with
Sarcophaga carnaria and the majority of the Diptera. Whereas,
some Hyinenoptera, whose females are apterous, Methoca and Myrmosa ,
for example, carry their females with them, and copulate in flight.
Others, as the butterflies, copulate sitting, but separate immediately
afterwards. The water -beetles unite themselves in the water, at least,
individuals are found there thus circumstanced ; and it appears to me
not improbable that the males are, on this account, furnished with a
perfect seizing apparatus, from a casual separation being so easy in that
medium. The queen bee, which constantly stops in her hive, quits it
at this period, that she may have connexion with the male outside, and,
probably, in flight ; the same is the case with the ants, who copulate
whilst the males and females rise and fall in large columns, intermixed
together, which, at a distance, appear like ascending smoke. We see
them quit their dwellings in large troops for this purpose ; they then
climb to the top of the nearest plants, thence to take their amorous
aerial expedition. The females of the Termites likewise quit their dwell-
ings, at the time of copulation, to be impregnated by the males, and
are then carried back by the workers, being left perfectly helpless by
the act.

The situation of the sexes during copulation may also be referred to
three chief positions, viz. upon each other, contiguous to each other, or
opposite each other.

The first is by far the most general position ; it varies only in that,
as the general rule is for the male to be placed above the female, in rare
instances it is reversed, as, for example, the flea, where the male carries
the female. The participation of both sexes in the common motion in
such positions, likewise varies. In some cases it is the female alone
which moves, and the male merely adheres firmly to the female, for
example, in the Capricorns. In other instances, this participation

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PHYSIOLOGY ,

wholly ceases, and the male is carried along by the female as if lifeless ;
thus, in many of the Chrysomelina, the male contracts all its limbs,
whereas the female endeavours to escape. Or both move at the same
time, as among the Diptera, which fly about thus occupied, and also
the swimming water-beetles ; or, lastly, the male alone moves, as in
Methoca ( Tengyra ) and Myrmosa, the females of which are apterous.

In their contiguous position, which we frequently observe in those
Cicadaria, which are furnished with spiny processes upon their backs,
and, consequently, cannot sit upon each other, all motion either entirely
ceases, or else both sexes move at the same time ; at least, I have fre-
quently detected this in some of our native Cicadaria , for example, the
species of the genera Jassus and Aphrophora.

The contiguous position is found chiefly in the crepuscular and
nocturnal Lepidoptera. In these, generally, all motion ceases; both
constantly remain in repose ; or else the female alone moves, drawing
the male with it, as in the cockchafer.

With respect to the duration of the act, we can say but little that
applies generally. From what precedes, it will have been seen, that in
some, for example, the butterflies, it quickly transpires. The same is
the case in the Hymenoptera, viz. in the bees. Others remain for
some hours in this situation, others again several days, as the
cockchafer. These, consequently, do not repeat the connexion, one
union being sufficient for impregnation : others, as the domestic fly,
appear to copulate several times successively : it is also probable that
the queen bee has intercourse with several males. Perhaps, also, the
intercourse may be repeated in such insects in which it rapidly trans-
pires, but many genera, for example. Ephemera, may make an exception
to this rule.

Peculiar organs adapted to facilitate the duration of the connexion,
are found in many insects. The Carahodea, according to Leon Dufour,
have hooks at the penis, by which they retain the female, and the
distended tarsi with their sucking cups in the male water-beetles,
are also subservient to this purpose. In others, namely, Panorpa ,
Laphria, Asilus, JDolichopus , Tipuia, the penis lies between fangs,
which retain the pointed apex of the female’s abdomen ; in the males
of many Meloe and wasps, the male antennae are hooked ; in the male
Crabros, the anterior tibiae are distended into lateral lobes, by means
of which they cling to the thorax of the females ; in the Lepidoptera, the
sexual organs of both sexes have hooks, which retain each other during

OF GENERATION.

320

copulation. In Melolontha, knobs of the penis correspond with lateral
pockets of the vagina, which promotes their firm adherence, or else the
penis itself is provided with barbs, which so affix themselves to the
vagina of the female, that the penis, after the completed intercourse,
remains in the vagina, as Huber says he has observed in the bees.
Audouin* also found the muscular portion of the penis completely torn
off in the aperture of the spermatheca.

Some naturalists, namely, Oken, have suggested the question whether
insects during copulation feel any voluptuousness, and the latter wishes
to deny it, but incorrectly, as I imagine. Whoever has observed the
ardour of the males before their intercourse, and their anxiety to attain
their object by every possible means, and when, having attained it,
their total abstraction in the delight of their ultimate success ; and also
how every other function visibly reposes, to admit of the entire energy
of the body being devoted to this most important one, must speedily, I
think, give up such an opinion. Is not, also, the ultimate gratification
of an internal urgent passion, for which no sacrifice is avoided, the
highest voluptuousness ? and does not the observation of every indi-
vidual copulation of insects most distinctly prove the presence of such
an urging passion ? The great multiplicity of nerves, likewise distributed
throughout the internal organs of generation, their turgescence before
and during copulation, and their exhaustion subsequently, admits of no
other explanation : the so-mucli-enjoyed pleasure alone can exhaust and
emaciate to the extent that we observe in male insects after its accom-
plishment, and not the mere satisfaction of the sexual instinct.

§ 208.

By means of the connexion between the male and female, the latter
is impregnated, which produces the development of the germs of the
eggs. Impregnation, consequently, is produced by the male by the
sperm secreted by the testes, and which is a milkwhite clammy opaque
substance of a peculiar smell, which chemical analysis finds to consist
chiefly of water, and to which is added a peculiar slimy substance, as
well as natron, phosphate of lime, and some nitrate of lime. Being
continually secreted by the testes, the sperm descends the vasa deferentia

* See his Lettre sur la Generation des Inscctes, in the Annales des Scienc. Natur.
T. ii. p. 281.

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PHYSIOLOGY.

into the vesica seminalis, and appears in both as a flocky matter, which
alcohol renders crumbly, and which is animated by infusoria of the
genus Cercaria , or others allied to it. According to Suckow *, they
resemble Volvox globator, but are more ovate ; but he probably over-
looked the thin tail, or it was perhaps torn away, which is constantly
the case, according to Nitzsch t > in the Cercarice which inhabit
fresh-water muscles, but, indeed, after these animalculae have quitted
the body of the muscle for the water. These animalculae ( Sper-
matozoa, according to De Bär) are developed by equivocal gene-
ration by the sperm, which surpasses all other organic fluids in its
generative power, yet they must not consequently be considered as the
truly animating and impregnating power in impregnation, but merely
as a proof of the healthy and genuine quality of the sperm, as they
are not found in that of old subjects, or of abortions or bastards.

During copulation, which the preceding paragraph has shown to take
place in insects by an actual connexion of the two sexes, this liquid
passes from the penis of the male into the vagina of the female, or,
according to Audouin’s repeated observation, into the spermatheca, into
the neck of which the penis protrudes. This is probably the cause why
the majority of insects, particularly the Coleoptera, possess such large
organs of generation, and that the spermatheca is the last of all the
appendages of the female organs. I also think that the frequently
long duration of copulation in many insects may be explained by the
spermatheca receiving the sperm. For example, the testicle cannot
secrete at once as much sperm as is necessary to fill the spermatheca ;
it must, consequently, after the ejection of what is contained in the
vesica seminalis, secrete an additional quantity, which secretion is
promoted by the stimulus given to the whole body by the act of copu-
lation, and is only terminated when the testes are exhausted in the
production of semen. We may thence explain the entire enervation
and frequently sudden death of the male after copulation (as for
example, in Ephemera ) ; the correlative size of the spermatheca with
the duration of the connexion, speaks also in favour of the opinion of
its being a place for the accumulation of the semen, which some
physiologists are inclined to doubt. We invariably find in those insects
which are long in copulation, large and broad spermathecae, for example,

* Hcusingcr Zeitschr. f. d. Org. Pliys. vol. ii. p. 261.

*|' Beitrag zur Infusoricnkimdc. Halle. 1817. 8vo.

OF GENERATION.

331

in Melolontha and in Meloe , whereas in those which are rapidly con-
nected ( Ephemera , Libellula, Musca), it is wholly wanting.

But Hunter’s* experiment proves that this appendage absolutely
contains semen, for by the application of the fluid contained in it, he
made the eggs of an unimpregnated female fruitful. Spallanzani f made
the same experiment, but with sperm from the male vesica seminalis,
and he also succeeded ; but Malpighi J, who made a similar one, was
unsuccessful, for he observed no development of the eggs. According
to Meinecke §, this vesicle is empty prior to copulation, and after the
laying of the eggs, but between these two periods, it is filled with a
viscous fluid.

If the semen be really received in this reservoir, we may ask, how
does impregnation ensue here as well as in those instances in which
the vesicle is wholly wanting ? We must have recourse to mere con-
jecture, for we have no positive observation upon the subject. It is the
usual opinion that the egg is rendered fruitful when it glides past the
aperture of the vesica seminalis, by the sperm suddenly falling upon it,
but this is contradicted by the observation that the development of the
egg commences even at the end of the oviduct, and that it has already
acquired a hard horny shell when it passes the vesica seminalis. Nor
does the conjecture explain the mode of fructification in those cases in
which that appendage is wanting. Opinions which have been pro-
pounded to explain it in the higher animals, for example, the theory of
absorption, whereby the sperm is conveyed through the blood to the
ovaries, cannot be applied to insects, which are totally deficient in
blood-vessels and absorbents. A third theory of generation maintains
the passage of the semen into the oviducts, which Suckow || states to
have positively observed. This opinion is not contradicted by the
distance of the oviducts, which, in many instances, is but trifling.
Consequently these oviducts are not analogous to the ovaries of the
superior animals, but to the tubes, the superior end of which only is
the ovary, whereas its lower end is the uterus, for, as Müller has
informed us, the development of the germen already commences there.

* Lectures on Comparative Anatomy, vol. iii. p. 370.

Versuch Uber die Erzeugung. PI. I. p. 245, &c.

t Opera Omnia, vol. ii. De Bombyce. p. 41. (Lugd. Batav. 1687. 4to.)

§ Naturforscher. 4 St. p. 115, &c.

|| Heusinger Zeitschr. f. d. Org. Phys. vol. ii. p. 262.

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PHYSIOLOGY,

If, therefore, an intermixture of the semen with the egg germ could
take place, it must occur likewise in insects in the uterus and not in
the ovary. But as much may be said against this intermixture in
the superior animals, viz. from extra uterinal and tubular pregnancy, we
find in insects also the successive development of several consecutive
eggs in the same tube standing in the way of its reception, for the
lowest egg only could come in contact with the spermen, and
without the re-adoption of the already obsolete opinion of the aura
seminalis, which Spallanzani has shown to be erroneous, we are
left precisely in the same situation by adopting or rejecting it.
We can consequently merely ascribe the incipient development of
the germs to the formative energy imparted to the female body by
the presence of the male semen, and to the stimulating excitement at
the time of immission. These germs are proportionally larger and
more perfect the closer they lie to the uterus, and, consequently, their
development must be progressive, if a determinate time and proportion
be given within which alone it can be elfected, and this it appears
absolutely necessary to adopt. Nevertheless, the semen may possibly
pass from the oviducts to the tubes, and here come in contact with the
lowest egg, which would thereby acquire its perfect development a
certain time before the formation of the shell. Thus, both the dynamical
and mechanical views have justice done them.

§ 209.

But before we pursue further the development of the egg, stimulated
by impregnation, we must investigate the degree of participation the
several appendages of the sexual organs have had in this impregnation as
well as in the formation of the egg. We have already become acquainted
with the function of one of the appendages of the female organs, viz. the
spermatheca ; the rest are, both in the female and in the male, according
to what we have above indicated (§ 140 and § 150), organs which
secrete a gluten. Their form, as we have there shown, proves this,
from its resembling that of the majority of the glandular organs in
insects, and also from the analogy of the superior animals, in which
similar glands are found in connexion with the genitals. But if their
secretion be positively a gluten, we may ask, what is the purpose of
this gluten in relation to impregnation and the formation of the egg ?
That it is not absolutely necessary, is proved by the many instances in

OF GENERATION.

333

which those appendages are entirely wanting, as well as, vice versa ,
their significant size necessarily contradicts the opinion that they are
unimportant to the function of generation.

With regard to the appendages of the male organs, their analogy to
Cowper’s and the prostate gland bespeak in some degree their
importance to impregnation. They contain a fluid which is thinner
than the semen, sometimes perfectly hyaline, but yet of a viscous
nature. This fluid pours itself out at the same time as the semen ;
consequently, after copulation the gluten organs become lax and flaccid,
whereas, previously, they were tense and turgid. Suckow therefore
supposes that the gluten merely increases the quantity of the semen by
rendering it more fluid, thereby giving it a general distribution, which
promotes the impregnation of the eggs. Burdach * considers this also
as the function of the prostate and Cowper’s glands.

The secretion of the female appendages is not the same as that of
those of the male ; it consists of a thicker, more viscous, yellow liquid,
which is not, as the former, poured out at the time of copulation, but
subsequently upon the passage of the eggs through the vagina. It is
here that the eggs are covered with this gluten, and are thereby affixed
to their place of deposition, for example, to the leaves and twigs of
plants. Many eggs derive their peculiar form from this coating, for
example, the long pedicle of the egg of Hemerobius ( PI. I. f. 14.) is
formed by this glutinous coat ; it is also what connects together the eggs
of Gastrophaga Neustria. The organs secreting this gluten are
deficient in those insects which deposit their eggs immediately in or
upon the food of the young, as for example, in the Ichneumons, many
flies, the Tenthredos and Cynipsodea, and many others, although not
yet proved by inspection.

A second function may consist in lubricating the vagina during
copulation, or the tube of the oviduct upon the passage of the eggs, and
thereby facilitating both processes ; at least, in some instances, for
example, in the Lepidoptera, we observe two different appendages, the
smaller one of which may possibly fulfil this function, and the other
larger one accomplish the first. By means of this gluten, thus generally
distributed throughout the egg ducts, the passage of the male semen
from the spermatheca to the egg tube may be facilitated and promoted.

Physiologie, vol. i. p. 460. k.

334

PHYSIOLOGY.

§ 210.

After impregnation, by means of copulation with the male, the
successive development of the egg germs, lying in the tubes, consecutively
ensues, namely, one after the other. Joh. Miiller * has instituted
admirable observations relative to this development in Phasma gigas,
and of which we shall here make an abridged extract.

If for this purpose we return back to the anatomical description of
the ovaries, we shall there find an already indicated connexion of the
egg tubes with the dorsal vessel. The mode of this connexion is thus :
a delicate, but, by its structure, strong filament, passes from the
superior extremity of each egg tube to the wall of the vessel, which is
a continuation of the heart, and which we have described as the aorta,
and it there unites itself to it. This connecting filament the discoverer
Joh. Miiller considers as a vessel which, passing from the aorta, trans-
pierces the extremity of each of the egg tubes, and thence forms its
internal coating. He further considers that the material which deposits
the egg germs comes from the aorta through these connecting filaments,
and that this connexion is of the greatest importance to their develop-
ment. Howsoever apparently just these conclusions may appear, they
have nevertheless an hypothetical origin. Nothing further is certainly
evident from his representation, than that a continuation of the egg tubes
in many, but not in all, cases, is attached to the dorsal vessel ; but that
these filaments are vessels which open into the dorsal vessel is not
proved, for he did not see the contents of the dorsal vessel pass into
these connecting filaments, which, indeed, in insects preserved in spirits
of wine, would be very difficult to detect. To attach, therefore, less
importance to this, the direct transformation of a blood-vessel into an
egg tube, appears inadmissible, for then the egg germ must be developed
in the blood-vessel, which merits certainly not the least attention.
Indeed, the same skilful observer has regularly found in the common
leech ( [Hirudo vulgaris) the nervous cord in the cavity of a central
blood-vessel f ; but this certainly cannot be cited as an analogy to the
transformation of a blood-vessel into an egg tube, which his earlier
discovery endeavours to prove, and a more analogous case is much less
to be found. I therefore consider this supposed connexion of the two
organs as nothing else than a superficial attachment of the egg tube to

* Nova Acta Phys. Med. T. xii. PI. II. page 620, &c.
f Meckel’s Archiv, für Anat. und Physiol. 1828. pp. 26 and 27.

OP GENERATION«

335

the aorta, but without admitting of the passage of the one into the other.
What Joh. Miiller considers as a continuation of the aorta, or as a
blood-vessel, I conceive to be the inner coat or mucous tunic; his egg-
tube tunic, on the contrary, as the exterior or muscular tunic.
Nevertheless, the filament may be hollow as far as the heart, without,
therefore, necessarily opening into the aorta. If such a passage existed,
and it were of physiological importance to the development of the egg
germs, it would be found in all female insects, but which, as Miiller
himself admits, is by no means the case. The contents of the hollow
connecting filament is a white granulated mass, which extends in it as
far as the heart, and can be even still detected where the filament has
already dilated into the egg tube. From this point the mass becomes
more and more consolidated together, and now assumes the appearance
of a thick lump, which is found between every two egg germs. We
first find the egg germs in the superior distended portion of the egg-
tube, and indeed in their peculiar oval form, whereas the mass between
two eggs is much smaller in compass, the egg- tube consequently between
every two egg germs is somewhat contracted. The egg germs, how-
ever, increase in size the lower they are placed in the egg tube, so that
the lowest is the largest of all, and the highest is the smallest. This
highest egg germ is almost of the same size as the mass placed between
it and the second one, which mass Miiller calls the placentula, and the
first egg germ also appears to have gradually formed itself from the
white granulated substance lying above it.

The development of the last egg germ, lying at the base of the egg-
tube, takes place thus : the placentula beneath it, in consequence of
impregnation, enlarges, and gradually re-models itself until it takes the
form of a cone, the apex of which is turned towards the egg germ.
Its base, or broad basal surface, therefore, separates the internal mem-
brane of the egg-tube until it comes into direct contact with the
exterior or muscular tunic, and becomes organically connected with it by
means of tracheae, whereby a dark annular girdle is formed at the base
of the egg tube, which Joh. Miiller calls the ring of the vessel.

Hitherto the egg germ has no pellicle, or shell, but it consists of a
thick, uniform, gelatinous mass. Now, after the placentula has dis-
tended itself, it is probable that the impregnation of the egg germ
proceeds from it ; and when this has taken place the shell commences
to be formed from above downwards, so that it, as it were, grows over
it, commencing at its upper end. Contemporaneously with it is the

336

PHYSIOLOGY.

cicatrix formed; it is a horse-shoe- shaped, bent, but longer longitudinal
projection, which lies upon one side of the egg, but which is yet
observed only in a few eggs, for instance, in Phasma. Its pur-
pose is not yet ascertained, although probably it is the analogue of the
tread, and consequently thence the development of the embryo would
originate. During this period the placentula retains tolerably long its
former conical figure, but it loosens and becomes lighter as a distinct
proof that it has lost something (the imbibed impregnating semen ?),
but henceforward it decreases with the increase of the shell and,
pellicle beneath it, and, at last, entirely disappears when the develop-
ment of the egg is completed. This, after the formation of the shell,
is limited to involution, and yet, at least in Phasma , a new structure
is added to it, namely, a crown- shaped appendage at the end of the
egg, in direction from the egg duct. This crown, which is formed of a
hard horny trellis-work, and which at its apex has a round aperture,
rests upon a correspondingly large orbicular depression in the shell ;
at this spot also the pellicle appears more delicate than elsewhere.
Beneath it is found a small vacant space, into which, the tracheae which
during the formation of the embryo, are forming in the vascular
membrane, together with their main stem, open themselves. This
delicate membrane may therefore justly be called the egg gill, for
through it the air passes into the egg. In those eggs which have no
crown, as is the case with the majority with which we are acquainted,
the orbicular depression is very small, but it lies likewise at the end
(PI. I. f. 23.). The indicated involution of the egg has chiefly reference
to the yolk, which has not yet completely filled the shell, it conse-
quently appears, as well as the pellicle which closely envelopes it,
folded upon the surface ; but it acquires consistency, and exhibits cells
in which, particularly towards its circumference in Phasma, a purple-
coloured mass is deposited, whereas in other cases it is yellow or
greenish. The more the yolk increases, the faster the folds disappear,
and when the egg has acquired the maturity requisite for being laid, it
entirely fills the shell, with the exception of the small vacant space
beneath the germen. During this period of ripening the inner tunic
of the egg-tube separates closely above the upper end of the egg, and
dissolves into a pappy consistence, which is excluded together with
the matured egg. The inner membrane with the next egg then
descends to the base of the egg tube, and the development of the new,
now lowest, egg germ proceeds in the same way.

OF GENERATION.

337

If we take a retrospection of the whole process of the development
of the germ to the egg we shall find that there are three distinct periods
in its progress. The filiform superior appendage of the egg-tube is
the first, for in it takes place the secretion of the formative matter, and
from here it descends into the egg-tube as a germen. The remainder,
probably albuminous portion, of the secretion, remains, as placentula,
between every two egg germs. The second period is the loosening of
the placentula by copulation. By means of it the internal tunic comes
into close contact with the exterior vascular one, in consequence
of which the ring is formed ; and at the same time the impregnation of
the germ takes place by the male semen imbibed from the placentula.
The ring, lastly, is the third period ; it promotes, by supplying the
placentula with atmospheric air, its capacity of appearing as a new
organic mass, so that it may be gradually imbibed by the growing egg.
The yolk thus becomes perfectly formed, and envelopes itself with its
second tunic, and then with its shell, which is hardened also by means of
the air from the ring. The formation of the egg is then completed, and
the period of laying comes, which takes place immediately, to make
room for a still immature egg. It is from this circumstance that some
insects, namely, those with many egg tubes, for example, the queen bee,
require a long time to lay all their eggs, and only in those with bag and
bladder-shaped ovaries, which are furnished upon their surface with
short egg-tubes (as, for example, Lytta and Meloe,) can the eggs be
almost all matured at the same time.

§ 211.

When, after all this procedure, the egg has quitted the maternal
sphere, a distinct life, namely, that of the embryo, commences in it.
If we first survey the structure of the laid egg we shall observe that it
consists externally of a horny shell, which becomes tolerably hard in
the air, and is in general transparent or colourless, but less frequently
decorated with particular markings and colours. Beneath this external
covering lies a second, finer, more delicate membrane, which forms the
case of the fluid contained within the egg. This fluid is the yolk,
(vitellus,) a yellow, whitish, or green, thick, granulated mass, which in
Pkasma is dotted with purple, and it chemically consists of albumen,
some animal glue, a yellow fat oil and sulphate and phosphate of natron*.

* See John’s Chemische Schrift, vol. ii. p. 112.

338

PHYSIOLOGY.

The separate albumen which is observed in the eggs of the Mollusca ,
Arachnida, Crustacea, many fish, and the Amphibia, and birds, is
therefore wholly wanting in the eggs of insects, which consist solely
of yolk.

We have as yet but little information of the progress of the formation
of the embryo from this fluid ; we only know from Suckow’s * observa-
tion in Gastrophaga pini that a small dark spot is formed in the centre
of the originally tolerably clear yolk, which he considers as the com-
mencement of the embryo. From this point, which we prefer consider-
ing upon the surface of the yolk analogously to the development of other
animals, and not as would appear from Suckow’s observation in its
middle, the formation of the embryo so proceeds that the ventral surface
along which the nervous cord runs first presents itself. This ventral
plate distends on all sides, gradually growing completely over the yolk,
which is thereby enclosed completely within the ventral cavity. This mode
of development has not yet indeed been observed in true insects, but the
development of the Crustacea and of the Arachnida speaks in favour
of it. After a short period the embryo appears distinctly as a half
moon-shaped body, at the end of which the head is already perceived
(PI. I. f. 24. a.). The embryo swims in a bright green but clear fluid,
the liquor amnii, and it is enclosed by two other membranes besides the
shell. The innermost, the amnion, which contains the water, is spongy,
and exhibits upon its inner surface small glands that are surrounded by
a bright margin, and it is covered exteriorly by a cluster of webbed vessels
(the same, c, c, c), which all proceed from a thicker main stem, which
opens into the orbicular portion of the egg filled with air. These
vessels, which doubtlessly convey air, consist, according to Suckow, of
but a single transparent membrane, and therefore differ considerably
in structure from true tracheae. Michelotti’s t experiments upon the
eggs of Liparis dispar and L. mori have proved that the eggs, during
their development, decompose air, viz., imbibe oxygen, and give out
carbonic acid, but only in a temperature of from 15° to 20°, whereas
beneath zero they leave the atmospheric air unaltered. This absorption
of oxygen is necessary to their development, for the eggs speedily die
in miasmatic gases, which are free from it. If now, as appears neces-

* See his Anatomisch. Physiologischen Untersuchungen der Insekten und Krusten-
thiere, vol. i. part i. Heidelb. 1818. 4to.

*|- See Pfaff and Friedländer französische Annalen, part iv. p. 48, &c.

OP GENERATION.

339

sary, this oxygen be imbibed from the above-mentioned orbit of the
egg germ, it can only be distributed by means of the vessels in the
circumference of the entire yolk. The second external membrane lying
over the amnion (the same, by b3) is a transparent, colourless, simple,
structureless tunic, which lies next to the egg shell, and clothes this
throughout, with the exception of the above-named space containing
air. It consequently corresponds with the membrane lying beneath
the shell in birds, viz., the chorion , which is here also as deficient in
vessels as among the birds. The resemblance to birds is very evident ;
a similar space containing air is also observable in birds’ eggs, and, the
same as here, the embryo imbibes the oxygen, which it requires for
respiration, from the air contained in that space. The allantoid is
wanting, and consequently the air vessels take their course upon the
exterior surface of the amnion, the yolk bag however is contained
within the ventral cavity. A canal to correspond with the navel cord is
consequently likewise wanting; the entire yolk bag lies within the
ventral cavity, and becomes the intestinal canal and stomach, and it is
thence perhaps that the stomach of caterpillars is so monstrously large.

The larger the embryo becomes the more distinctly do the several
organs display themselves. Interiorly Suckow first observed the intes-
tinal canal, almost contemporaneously with the external formation,
from the simple reason that so soon as the ventral plates had united at
the back the yolk bag must necessarily present itself as the internal
nutrimental canal. It is evident that the closing of the anus in many
larvae stands in close relation to this reception of the entire yolk
bag. Suckow also observed, towards the close of the embryo life, con-
strictions upon this internal nutrimental canal, which separated the
oesophagus and intestine from the stomach ; until then it remained
what it was, a longitudinally distended simple bag. Now appear the
first traces of air vessels, in the form of tubes, one of which runs on
each side of the body, and from division to division sends forth fasciculi
of branches, which spread themselves to the intestinal canal. But
during the embryo life the tracheae do not enter into action, the stig-
mata are consequently closed, and their function commences only upon
the exclusion from the egg. The dorsal vessel also developes itself and
gradually commences action, at least distinct pulsations have been
observed in embryos shortly prior to their quitting the egg shell. The
sexual organs are also observed during the last few days of the embryo
period, they present themselves in both sexes as small knobs with

z 2

340

PHYSIOLOGY.

delicate ducts, which unite beneath the intestine into a short clavate
evacuating duct. The commencement of the nervous system consists
of two extremely delicate scarcely perceptible filaments into which the
nervous matter by degrees accumulates ; they then approach together,
and connect themselves at different spots, thus forming the ganglia,
and anteriorly the brain, which in the embryo is still very soft and
almost fluid, and therefore very destructible. The muscular layers
beneath the skin are also indicated, and particularly the head, with its
mandibles, the legs and the anal horn become developed, as the most
important external organs. In clothed caterpillars insulated hairs
appear also upon the skin. We thus frequently see the matured
embryo in its convoluted position through the thin egg shell (PL I.
f. 22). After the termination of these evolutions the young larva
strives for freedom and greater independency, it bores through the shell
at its most delicate part, namely, at the orbit, and then comes forth
from out its prison, and immediately commences its first appointed oc-
cupation, feeding voraciously. Producing this object many larvae de-
vour their own egg-shell immediately after quitting it.

§ 212.

In some few insects the exclusion from the egg takes place in the
mother’s body, and these therefore bear living young. Such insects
are called ovoviviparous.

One of the most common instances of this kind is presented by the
Aphis. In these the female bears through the summer living young
ones, and in autumn it lays eggs. According to Bonnet, nevertheless,
egg germs are found in the ovaries, as in all other insects ; these deve-
lope themselves in the duct, here the young creeps forth, and is thus
born living. Bonnet assures us that, upon an anatomical inspection, he
discovered egg shells and young ones in the duct. According to other
observers, viz., Kyber, upon Aphis Dianthi, eggs are never laid, but
young ones constantly born, so long as the individual has not copulated ;
a copulated and consequently impregnated female lays only eggs ; but
Bonnet has nevertheless made it probable that the egg laying (as was
remarked above, § 204,) is the consequence of the colder autumnal
temperature, since the eggs more easily bear the intensity of winter
than the young. Kyber’s Aphis might therefore have continued
producing living young ones in consequence of its being kept in a
warmed apartment. De Geer, however, observed Aphis Abietis never
to produce living young ones, but always eggs.

OF GENERATION.

341

The flesh flies exhibit another instance of ovoviviparous production in
insects. It is well known that these flies ( Sarcophagce ) deposit their
larvae upon putrifying flesh, and the young immediately after their
birth proceed with the removal of the substance upon which they were
deposited. According to Reaumur* * * §, who has described and figured
the ovary, the larvae may be found in the spirally twisted egg tube, and
which, we may remark incidentally, according to him contains more
than twenty thousand larvae. According to De Geer t, the eggs first
descend the egg duct after their development at the base of the egg
tube is completed, and each ovary contains but from fifty to eighty
germs. Their increase is nevertheless very rapid, for in from eight to
ten days the larva is grown, and again after eighteen or twenty days
the fly appears. If we admit merely the smallest number of eggs, and
allow four weeks to the development of every individual, we find, upon
supposing an equality of both sexes in each generation, in one summer
(from June to October) a produce of more than five hundred millions,
therefore about half as many individuals as there are human beings
upon the whole earth, according to the received opinion. Meantime,
how many are destroyed as larvae by their multitudes of enemies ? how
many also as flies are there not consumed by birds ?

Similar cases of an early exclusion from the egg within the body of
the mother has been observed in other genera. Reaumur J found the
larvae of a small Tipula , which, to judge from his figure, apparently
belongs to Meigen’s genus Ceratopogon, in one of his boxes, where also
they changed into nymphae. He obtained from these the fly which
subsequently produced long worm-shaped larvae ; indeed, upon a slight
pressure, he squeezed them fully developed from the body of the
mother. According to Kirby and Spence § also many Cocci and bugs
bring forth living young ones ; the latter from the observation of
Busch, upon which, however, I have not been able to obtain more
detailed particulars.

But we have, more positive observation upon the development of
the Diptera pupipara. The remarkable form of the ovary of the
female is shortly indicated above (§ 136. III. 2.). The egg descends
from the small ovary through the egg duct into the large, bag-shaped,

* M^moires, &c., vol. iv. part ii. p. 153. PL XXIV. f. 1. Edit, in 12mo.

f lb. vol. vi. p. 31. PI. III. f. 5 — 18.

X lb. vol. iv. partii. p 168. PI. XXIX. f. 10 — 15.

§ Introd. to Entom. vol. iii.

342

PHYSIOLOGY.

distended uterus, into the superior narrow aperture of which two ramose
vessels, which terminate in blind filaments, open themselves, and which,
according to Ramdohr *, are secreting vessels that convey nutriment
to the larvae, and in this uterus the egg changes into the larva, and
subsequently into the pupa. As such the young is born, nearly of the
size of the mother, and enclosed in a hard, simple, smooth shell, with-
out any annular constrictions, and which shell is furnished at one
extremity with a cover. This springs off so soon as the pupa has
passed through this stage of its existence, and the perfect insect then
issues from the pupa case. We therefore here observe a true develop-
ment in the uterus similar to that of the mammalia, the larva receives
within the body of the mother, and by means of her, its first nutriment,
and in its state of puberty, consequently much later than the young
mammal, it comes forth into the world. This period also quickly
transpires, so that we may almost assert that the young one is capable
of re -producing the very moment it is born ; a solitary instance
unparalleled throughout the whole organic world.

§ 213.

The number of the eggs laid by a female insect is generally very
great. We have above very recently shown the possibility, at least, of
a monstrous posterity in the flesh fly ( Sarcophaga carnaria ), and yet
the female, according to De Geer, lays at the greatest number not more
than 160 eggs. This number, which may be considered as a very
general average, is in many instances exceeded ; in fact, we must feel
astounded at the incalculable multitudes which different authors give
as the produce of a single individual, numbers which are exceeded only
by the almost incredible productive powers of fishes. According to
Smeathman, the female of a Termites lays in one minute sixty eggs,
and therefore in one day more than 86,000, which, however, does not
by far terminate her period of laying. A small insect, which is found
in numbers upon the Chelidonium majus, Lin., namely, Aleyrodes
Chelidonii, Latr., (Tinea proletella,!^ in.), lays, according to Reaumur,
20,000 eggs (but the number of eggs is much exaggerated, it is only
between twenty and thirty f ) ; in the queen bee it varies from 5,000
to 6,000 : the ant lays from 4,000 to 5,000, the common wasp ( Vespa

* Magaz. der Gesellsch Naturf. Freunde zu Berlin, 6. B. s. 13 L
f Author’s MS. addition.

OF GENERATION.

343

vulgaris ) about 3,000, the Coccus from 2,000 to 4,000. If even
these considerable multitudes are to be classed among the rare instances,
yet a posterity of a thousand individuals in one generation is very
common among insects. We find this number among the majority of
Noctuce ; Lyonet considers this number as usual in Cossus ligniperda.
Euprepia caja lays about 1,600. In the silkworm the average is about
500. Other orders are less fertile, for example, the Coleopter a ; in
these the average is fifty : many, as the Chrysomeloe, lay more (viz.,
Chrysomelce polygoni ) ; others, for example, Meloe , Lytta, which have
baccate ovaries, also lay many eggs, namely, from 600 to 800. The
burying beetle ( Necropkorus vespillo ) is said to lay only thirty eggs,
and the flea, according to Roesel, only twelve ; many Diptera, as the
gnats, some dozens ; others, particularly flies, very few, from six to
eight : Musca meridiana, according to Reaumur, lays only two eggs,
but certainly not in the whole, but atone time. The Diptera pupipar a,
the account of whose development we have given in the preceding
paragraph, always lays but one egg, or rather brings forth but one at a
time ; and it is the same with the Aphidce, who bring forth a numerous
progeny, but only one at a time, at longer or shorter intervals, whereas
insects which lay eggs continue to lay until their entire stock is
exhausted. We may readily comprehend the incalculable number of
insects from this multitude of eggs laid by a single one. Reaumur
observed a Phalena from whose numerous eggs 350 living young ones
were developed ; many of them died as caterpillars, so that only sixty-
five females were found among those that passed through their several
metamorphoses ; but even this number were calculated to produce the
following year a posterity of 22,750, which in the succeeding one, by
the same calculation, would give a succession of 1,492,750 young ones.
A single Aphis likewise, by Reaumur’s calculation, produces in the
fifth generation a succession of 5,904,000,000, and it is well known
that the great great grandmother still lays eggs when the ninth member
of her descendants is capable of re-production.

344

SECOND CHAPTER.

OF NUTRITION.

§ 214.

Having now, in the preceding chapter, pursued the history of the
formation and development of the insect embryo, proceeding from the
most general phenomena of generation, and then directly applying
them to the class of insects, I shall therefore now closely investigate
the progressive advancement of the young, now rendered independent
and excluded from the egg, and investigate the means whereby its
development is attained. For this purpose we take the insect in its
present stage, as it now exhibits itself, either as maggot, caterpillar,
or larva, without asking why it assumes this or that peculiar form,
reserving the answer to that question to the following chapter of
“ Somatic Physiology,” where it will receive its reply, in connexion
with the inquiry into the forms of perfect insects in general ; and we
therefore now direct our attention to the means appointed for the fuller
development of the individual itself.

These are found to consist in its nutriment, namely, in the assi-
milation of the newly received organic substances. The young larva
must feed upon fresh organic matter, either vegetable or animal, and
transform it into its own substance if it is to live. An inquiry into
the several kinds of food, and their modes of reception and assimi-
lation, will constitute the subject of the ensuing chapter.

§ 215.

If we take a general survey of the process of nutrition in general,
as we find it in the progressive development of animal organisation, we
shall perceive that an internal cavity presents itself as its first
organ. In this cavity, which is called the stomach, the food is
received, transformed, and the unassimilating portions rejected either
through the same orifice at which it was received (the mouth), or at
another aperture placed at the opposite extremity of the cavity of the
stomach (the anus). So long as the food remains in this sometimes
simple or tubular cavity, which is occasionally furnished with auxiliary

OF NUTRITION.

345

distensions and pockets like so many lateral purses, the digestible
matter is imbibed by the parietes of the cavity, and so transformed
into the substance of the body. We find this first and most simple
mode of nutrition in the lowest animals, the Infusoria , the Polypi, the
Acalephce, and many of the intestinal worms.

The digestion of the food can only be perfectly accomplished when
it has been previously adapted thereto by the secretions of peculiar
organs, which, as it were, kill and decompose it. Where such
auxiliary organs present themselves we find the cavity of the stomach
more complex, longer, and tubular, and making several convolutions in
the body. The first of the secreting "organs that is added to the
digesting cavity, which we may henceforth call the intestinal canal, is
the liver, which is a glandular body that pours its secretion into the
anterior half of the intestine beyond the stomach, and which thereby
renders the chyme fit for absorption. The second secreting organs are
the salivary glands : they first present themselves in such animals which
take hard food, and by their secretion cause the transformation of the
coarse materials into a uniformly fluid pap. We find upon this grade
of the development of the digestive apparatus the muscles, snails,
Crustacea , Arachnids, Myriapodes, and insects. Many of them want
the salivary glands ; many have a multilobed liver, as the snails ; others
have a small one, in the form of tubular canals. The deficiency of an
anus is a rarity in this grade of organisation, but we hovrever find it
among insects.

Upon the third and last grade we observe not only the preceding
secreting organs both more perfect and numerous, but other new ones
present themselves, some of which pour fluids into the intestine, as the
pancreas; and others rectify the absorbed chyle, as the milt and kidneys ;
of the last, however, we observe occasional prefigurations in the snails
and insects. This most perfect development of the digestive apparatus
is found in the Vertebrata.

§ 216.

It does not suffice that the digestive organ should thus become by
degrees more perfect, thereby facilitating the separation of the nutritive
matter, but the imbibed and decomposed chyle must be subjected to
another change before it can be transformed into the organic mass. This
change is produced by means of respiration, a function which consists
in adding to the nutriment a new substance present in the atmosphere.

316

PHYSIOLOGY.

viz., oxygen. This is, as it were, a second repeated killing of the
nutriment, or, in its true sense, a real consuming of it. Where this
consuming attains its culmination the blood and consequently the whole
body becomes warm, and thence arises, at least chiefly, the uniform heat
of birds and mammalia.

A distinct organ of respiration is entirely wanting in the lowest
animals, viz., in the Infusoria , Polypi, Acalephce, and many of the
intestinal worms ; and if they really breathe it can only be by means
of the exterior integument, in the same way as the internal skin
imbibes the nutrimental juices from the food. The first instance of a
true respiratory apparatus speaks in favour of this opinion, for where
found it is a continuation of the exterior integument, a sort of tufted
or ramose fold of the skin, which projects into the medium, loaded with
oxygen. Such respiratory organs, which are called branchiae, we find
in the muscles, the majority of snails, and in all the Crustacea, and
even among fishes and the naked amphibia, either throughout their
whole lives or during the time they remain in the water. The respiratory
organ being merely at one part of the body, a motion of the juices to
this spot is requisite, and thus originate the vessels as new organs con-
necting the functions of the intestinal canal and branchim. Vessels
must consequently be found in all animals with a partial respiratory
apparatus, and they may therefore be deficient in such as have this
apparatus universally distributed.

If the fold of skin which becomes developed to the respiratory organ
pass inwardly, it is then called not gill, but lung (pulmo). The
medium, which is generally the air that contains the oxygen, is received
into the lung, wherein the oxygen becomes incorporated with the nutri-
tive fluid. This also is in general merely partial, and then consists of
membranous bags, which in its highest grade of organisation consists
of a web of small cells, that by degrees unite into common ducts, the
last and largest of which, the trachea, opens outwardly. Vessels convey
the nutritive fluid (the blood) to the surface of these cells and bags,
and by means of other vessels it is conducted hence to all the parts of
the body. These organs of respiration are common to the majority of
amphibia, all the birds, and mammalia ; their first indication is found
in the pulmonary Mollusca and in the Arachnida. A universally dis-
tributed lung, the analogue of the similar branchia, would require no
vessels, as the oxydisation of the nutritive fluid would take place
everywhere. We also absolutely find that animals Avhose body is

OF DIGESTION.

347

traversed throughout by tracheae, which may be considered as separated
pulmonary passages, are deficient in a vascular system, and the frag-
ment of it which is present more serves to promote a motion in the fluid
that decomposition may be prevented by its stagnating during repose.
Such animals are insects, as well as a portion of the Arachnida and
Myriapoda.

We have thus become acquainted with the general mode of nutri-
tion : we have seen that it requires two agents, viz., one to prepare the
nutritive fluid (the intestinal canal), and another to make it organisable
(branchiae, or lungs), as well as frequently a third to conduct the fluid,
and which acts as a connecting member between the two others. We
will now investigate in detail the functions of these three agents in
insects in the order in which we have above noticed them.

§ 217.

I. FUNCTION OF THE INTESTINAL CANAL, DIGESTION.

The activity of the digestive organs commences with the reception
of food. This in insects takes place in a double manner, namely, by
biting and chewing, or by the suction of fluids.

All the mandibulate orders, it is very natural to suppose, take their
food by manducation ; consequently the Coleoptera , Orthoptera , Dic-
iyotoptera, Neuroptera, and a portion of the Hymenoptera. In them the
horny mandibles, which move horizontally in opposition to each other,
bite the portion off which it is the function of the labrum to retain, thus
holding it between them ; the same is done beneath by the maxillae and
labium. When the part is separated it passes between the maxillae, where
it is readily comminuted, during which operation it is held by the labium.
It is then passed to the posterior parts of the cavity of the mouth,
whence it glides down through the pharynx and oesophagus to the
stomach. In many insects, namely, the Coleoptera , the mouth and
pharynx are upon the same plane, so that it merely requires to be
pushed forward to get into the stomach. Such beetles as the Cara-
bodea and Dytici chew but little, perhaps from their possessing a
proventriculus in which the food undergoes a second comminution.
They also feed only upon flesh, which, as in the carnivora among the
mammalia, requires no mastication previous to its being swallowed.
In the herbivora, for example, the grasshoppers, particularly of the
genus Gryllus, which possess no true proventriculus, but merely a
crop provided with teeth, the food is longer chewed. The pharynx

348

PHYSIOLOGY.

therefore lies higher than the cavity of the mouth, and the meal has to
describe an arch, and to pass over the internal skeleton of the head
before it can get into the crop. It is very easy to convince oneself of
the continued chewing motion of the broad molar-shaped mandibles of
these insects, and in which the maxillae also take an active part. They
are therefore analogous, both in this respect as well as in many others, to
the graminivorous birds, particularly the Gallinoe , or, to indicate a higher
parallelism, to the ruminants amongst the mammals, only that their
rumination does not take place in the mouth, but as in the birds, in
the proventriculus, or crop. In the Lamellicornia, Pelodea, and
Capricorns, which all have complete oral organs, the power of masti-
cation decreases in proportion to the decrease of the proventriculus.
Their food also is partly more fluid and more decomposable, so
that the hairy maxillae laps it up, and it is thus readily taken into
the mouth. A striking instance of this mode of feeding is ex-
hibited by the stag-beetle, which, as is well known, laps up the
exuding juices of the oak, and for this purpose is provided with very
hairy maxillae. In the ontkophagous Petalocera the mandibles exhibit
an analogous form adapted to their purpose, being flat, thin, lamellate,
or rather shovel-shaped, to take up their thin food and convey it to the
mouth. The Chrysomelce either devour leaves, or as in the Gallerucce ,
(G. Alni, Viburtii, &c.), sweep off the pollen of flowers with their
maxillae. They want the proventriculus, and consequently their food
requires to be masticated in the mouth ; but as they bite off but small
pieces the chewing is of shorter duration. This is the case also with
the larvae of the Lepidoptera, which, without exception, bite and chew,
but they separate such small pieces that they can swallow them without
their requiring much comminution ; at least they continue biting off
fresh pieces without stopping to masticate that already in their mouths.
The masticating Hymenoptera , for example, the Tenthredonodea and
Ichneumons, devour the pollen of flowers, and their honey, which they
lap up with their flat, thin, shovel-shaped maxillae, or else bite off in
larger pieces by means of their dentate mandibles. They masticate
certainly but slightly, and yet they want a proventriculus, which has
always more or less relation to the duration of the mastication of the
food. The Dictyotoptera and the Libellulce masticate longer: but
they are predaceous, and devour insects which they capture. For this
purpose they are furnished with long hook-shaped mandibles and short
but broad maxilloe armed with long teeth. It is distinctly seen how

OF DIGESTION.

349

they masticate small insects with their maxillae, swallowing them
gradually, holding their bodies the while with their mandibles. The
hard parts, namely, the wings and feet, they drop after they have
devoured the soft body. They want the proventriculus, and therefore
the maxillae completely comminute all their food. The Dictyoloptera
mallophaga likewise masticate, as, according to Nitzsch, they feed upon
the down of feathers ; they want the proventriculus, but they have a
large crop, in which their swallowed food softens for a time and is
prepared for digestion.

Upon reducing the different modes of mastication of insects to one
general view we shall find it to present the following : —

Mandibulate insects devour,

1. Firm materials, which they bite off piecemeal, and which are

masticated.

a. Merely in the mouth. Libellulce.

b. Less in the mouth, but more in the proventriculus. Cara-

hodea , water beetles, and Staphylini.

c. Both in the mouth and proventriculus. Grylli .

d. Neither in the mouth nor in the proventriculus, as the latter

is wanting, whereas the creature bites off but small pieces,

which can be swallowed entire. The caterpillars of the

Lepidoptera ; the Chrysomelce.

2. Fluids or substances which easily dissolve.

a. They are swallowed as separated by the mandibles. Onilio-

phagous Petalocera, Peltodea, Capricorns.

b. They are lapped up by the pencillate maxillae and sucked

out in the mouth. Lucani, Tenthredonodea, Ichneumons.

§ 218.

Many kinds of sucking approximate to this last mode of taking food.
The Phrygance make, as it were, the passage from the mandibulate to
the haustellate insects, their oral organs being formed wholly upon the
type of the mandibulates, although they only take their food by suction.
Their mandibles are small, and entirely unadapted to biting, and have
the appearance of two little knobs at the base of the labrum (PI. VI.
f. 9. a , a), whereas the upper lip, or labrum, is long, narrow, lancet-
shaped, internally canaliculated (the same, f. 9.), the same as the still
longer labium, which is distended at its extremity into a spoon-shape
(the same, f. 10. d.) ; with it the two-jointed, flat, lobate maxillae (the

350

PHYSIOLOGY.

same, c, c.) stand in close connexion, as well as the four-jointed max-
illary palpi (<?, e.), at the base of these maxillae, whereas the three-
jointed labial palpi hang in front of the apex of the labium closely to the
bone of the tongue (the same, f. 11. ff). We consequently find all
the organs of mandibulate insects, and yet nothing is more certain than
that the Phryganea do not bite, but only suck. Their food consists
of the sweet juices of flowers, and we meet with the perfect insect only
upon flowers, particularly upon the umbelliferce , syngenistce , nymphece ,
and similar plants, which grow in the vicinity of water, whereas the larvae
live in water and have distinct and separate manducatory organs, and
prey upon other minute water insects.

We now proceed with the general mode of taking food in haustellate
insects. Their oral organs are thrust into the material which supplies
them with food, and is sucked by means of the sucking stomach through
the canal formed of the labrum and labium. The sucking stomach,
according to Ramdohr’s * representation, is a double bladder-shaped
appendage at the lower end of the oesophagus. When distended the
air within it, as in the oesophagus, is rarefied, which causes the ascent
of the juices of flowers into the oral tube ; it then comes into the
oesophagus, which swallows it into the stomach, and this continues so
long as the sucking bladder is distended, and only upon its contraction
does it cease. This sucking stomach is found (see § 103) in almost
all insects provided with haustellate organs, and by its distension
the ascent of the liquid nutriment is occasioned. It appears to be
peculiar to haustellate insects, and to present itself in this form in no
other animals. The swimming bladder of fishes only has by its open-
ing into the oesophagus some resemblance to the sucking stomach of
the Diptera, and Treviranus + therefore compares it with that organ,
a parallelism which, although not supported by the functions of the
two organs, yet by their corresponding situation, form, and struc-
ture deserves consideration. The other Dictyotoptera, as Hemerobius ,
Myrmecoleon , Ascalaphus , and Semblis, have no sucking bladder, and
therefore do not suck, but bite. They are in general carnivorous, and
are therefore made to bite and manducate their food.

The wasps and the bees may be classed next to the Phryganea, from
their mode of sucking their food. The conformity is greatest in the wasps.
Their labium and maxillae form a similar apparatus, but they are pro-

Verdauungswerkz. PI. XYI. f. 2.

f Vermischte Schriften, vol, ii. p. 156, &c.

OF DIGESTION.

351

portionally longer, and project beyond the anterior four-lobed portion
called by entomologists the tongue. At the base of the labium lies
the pharynx, covered by a triangular valve, which Treviranus * calls
the second tongue ; but it is impossible that this valve should be a
tongue, as it lies over the orifice of the pharynx, and evidently serves
to close that organ, comparable in form and function to the uvula of the
mammalia. The sucking stomach is not so distinctly separated from
the oesophagus, but rather an anterior crop-like distension of it (see
§ 103), and into this crop the funnel-shaped orifice of the mouth pro-
jects. When it distends itself this orifice of the stomach approaches
closer to the upper thinner commencement of the oesophagus, and the
passage of the food into the stomach is thereby promoted. This dis-
tension also causes the ascent of the honey into the oral tube, and when
it has arrived at the pharynx deglutition passes it on. Treviranus has
convinced himself of the correctness of considering this crop as a suck-
ing stomach, as well as of its corresponding function, or at least of that
of a similar appendage to the oesophagus of the majority of haustellate
insects, by dissecting them alive ; he always found this bladder empty,
and it, as well as the pharynx, in a peristaltic motion, or interchanging
distension and contraction, which was likewise observed before him by
Malpighi f and Swammerdam J, who, however, did not detect its
function. According to Meckel § the sucking bladder contains also, at
least in the Diptera, fluids of different colours ; Ramdohr || calls it a
food bag, and ascribes it exclusively to the Diptera. But -whosoever
shall follow Treviranus in his description, without predilection or pre-r
conceived ideas, must, I am sure, be speedily convinced ; it would be
absolute obstinacy, after such clearness and such a distinct insight into
the suctorial apparatus of insects, to require further proofs ; an hypo-
thesis which explains everything, is no longer an hypothesis even if, as
however is not the case here, it is not supported by observation.

Let us turn to the bees, in which, with a very similar form of the
oral apparatus, it is however more difficult to comprehend their mode
of sucking. Instead of a lobate tongue we find in the bees a long, fili-
form, hairy, hollow proboscis, which at its base has two membranous
lobes (Latreille’s Paraglossce , PI. VI. f. 7* a.) ; the aperture of the

* Vermischte Schriften, vol. ii. p. 134.

•f* Opera Omnia, Lugd. Bat. 1687, tom. ii. p. 44.

$ Biblia Naturae, p. 138. a. § Vergl. Anat. vol. iv. p. 92.

|| Abhand, über die Verdauungswerkz. p. 11.

352

PHYSIOLOGY.

mouth or pharynx likewise lies at the base of this proboscis covered by
a valve, as in the wasps. From it the simple proboscis passes on to the
stomach, distending in front of the latter into the sucking bladder. A
peculiar vessel originates from the canal of the proboscis, the course of
which indeed Treviranus could not completely follow, but which pro-
bably passes beneath the cerebellum and opens into the oesophagus ;
the ducts of the salivary glands also appear to open into the oesophagus.
Treviranus therefore considers that this canal within the proboscis is
the organ which imbibes the nectar, but he passes over in silence the
function of the mouth, or orifice of the pharynx. If, however, I shall
not undertake to question the justice of his remarks without adequate
investigation, it yet strikes me as evident that the oral aperture or
orifice of the pharynx must have some particular and important relation
to the mechanism of nutrition, perhaps harder and larger particles of
food, such as the grains of pollen, are swallowed by it, or, which is yet
more probable, that the honey, which the neuter bees are known to cast
up, is rejected through this aperture.

The suctorial apparatus of the Lepidoptera differs still more widely.
Their oral organs consist of two spirally convoluted hollow probosces,
which represent the maxillae of other insects (see the detailed descrip-
tion of these organs at § 70). Into each of these sucking tubes a
branch of the furcate oesophagus opens (§ 102). This itself is a nar-
row tube, which becomes the stomach at the commencement of the
abdomen ; and here, closely in front of this transition, it has a simple or
double sucking bladder. The two probosces form, united, a central canal,
into which the ducts of the salivary glands open. In these insects
therefore the simple oral orifice has entirely disappeared, instead of
which we find two proboscideal sucking mouths, through which the
nectar, which is the universal food of the Lepidoptera, ascends, by the aid
of the sucking bladder, and by means of the above described mechanism.
Another corroboration of the correctly supposed function of the bladder,
and of its connexion with the business of sucking the aliment, is found
in its being very small in those Lepidoptera which have a short conical
proboscis, as in Euprepia caja and Cossus ligniperda , whereas in the
butterflies, which have a long proboscis, and also in the sphinges, it is
of large compass.

The proboscis of the Diptera has been already above (§ 70) amply
described ; and we have also learnt from the anatomical description of
the intestinal canal (§ 103) that they have a large sucking bladder.

OF DIGESTION.

353

which opens into the oesophagus through a long narrow canal. Conse-
quently they suck their fluid aliment in the same manner. The setae,
which lie in the sheath of the labium, are thrust into the substance
which they suck, moving up and down like a pump during the opera-
tion, and thus the fluids ascend into the stomach by the alternating
distension and contraction of the sucking bladder. If we attentively
observe a gnat or fly thus occupied, the opposed motion of the setae may
be distinctly seen, and we also detect that the blood does not flow in a
continued stream, but at distinct intervals; so that when the gnat has
swallowed a drop a fresh drop follows it, but there is a momentary
cessation of the operation between.

The flea and the Diptera pupipara do not possess this sucking
bladder, and their proboscis differs by not possessing the lower fleshy
sheath ; they hereby approximate to the Hemiptera , whose rostrum is
articulated, and they likewise have no sucking bladder. According
to Treviranus * the setae (see § 70) > of which their rostrum is formed,
are hollow, and vessels originate from their cavities which open into the
first stomach by means of narrow canals (see PI. XX. f. 3.) ; the oeso-
phagus itself opens into or beneath the tongue, seated between the setae,
whither also the ducts of the salivary glands pass. He therefore
assumes that the liquid ascends the hollow setae, as in capillary tubes,
and passes into the stomach through the vessels. I consider this opinion
doubtful, as it appears to me too mechanical, for hereby the oesophagus
would become superfluous, and particularly as the Hemiptera thus
imbibe their food throughout their whole lives. I should prefer con-
sidering the lateral distension, which is found at the commencement of
the stomach in many bugs, and the pyriform distension at the end of
the oesophagus, into which the second stomach returns, as the analogue
of the sucking bladder, and thus suppose in them a mechanism con-
formable to that found in the other orders. Ramdohr also, who has
figured the intestines of many bugs, never found tubes conducting
from the setae to the stomach.

§ 219.

Their own variety conforms tolerably with the various modes of their
taking food. Thus naturally fluid aliment can only be imbibed, and
that which is of a firm consistency must be bitten off and masticated.

* Annalen der Wetterauschen Gesellsch. f. d. Ges. Nat. I. 2, p. 171.

A A

354

PHYSIOLOGY.

But more important than these differences, derived from the external
quality of their nutriment, are those which refer to their being either
of vegetable or animal origin. Thus the food of insects may be divided
into two groups, so that we can class it into four different kinds, each
of which again admits of subdivision, according to whether it be fresh
or whether putrefaction have already commenced, which we thus
arrange : — -

I. From substances requiring comminution. These are,

1. Of the Animal Kingdom, and are,

a. Fresh and uncorrupted, and generally consisting of living
individuals obtained by force.

The predaceous beetles, viz., the Cicindelce, Carabodea,
Hydrocanthari , and Staphylini, support themselves by this
kind of food. All devour other insects, chiefly larvae, which
they obtain by capture, or the flesh of dead and fresh verte-
brata to which they can procure access. Some, as the Dytici ,
are said to attack living fish, and eat out their eyes ; others,
as Hydrophili, devour the spawn of fishes and frogs, and
even such young frogs and tadpoles as they can master.

b. Animal substances in which putrefaction has already com-
menced, particularly carrion.

The large family of carrion beetles ( Peltodea ), especially
feed upon such substances. Their larvae live wholly in pu-
trescent vertebrata, and devour their flesh, and the perfect
insect also derives its nutriment from it. The burying
beetle ( Necrophorus ) buries small vertebrata, depositing its
eggs in their body ; thus innumerable carcases are destroyed.
Smaller beetles, for example, the Aleochara, many Sta-
phylini, Corynetes, &c. assist them in this business. Others,
again, consume only the dried skins of animals and their
clothing, as the fur beetles ( Dermestodea ) and the clothes
moths (Tinea pellionella, &c.).

c. Excrementitial substances, animal excrements.

The majority of onthophagous insects are extremely fond
of the excrements of the herbivora. But this cannot be con-
sidered as distinctly animal or vegetable matter, but as an
intimate mixture of both; therefore all beetles which devour
such excrements are fed upon both animal and vegetable
substances. To these belong all the onthophagous Petalocera,

OF DIGESTION.

355

viz., Copris, Onthophagus, AteUchus, Gymnoplenrus, Onitis,
Aphodius, and many others ; then the Histerodea, many
Staphylini, the genus Spheridium, as well as the larvae of
innumerable Culices and flies. But as these substances have
considerable affinity with carrion, and the onthophagous
insects with the Peltodea, many species of both kinds feed
indiscriminately upon both substances.

2. From the vegetable kingdom.

a . Corrupt vegetable substances.

Many insects live upon the rotten portions of trees, as the
larvae of Lucanns and Oryctes ; others devour the corrupt
substances which are deposited beneath the bark of dead
trees, for example, Hypophleus , Engis , Ditoma , Colydium,
Rhyzopkagus , and other genera of this family. The larvae
especially appear to derive their nutriment from such cor-
rupting, fermenting, or decomposed portions of plants.
Lastly, according to Reaumur *, the larvae of the Tipula
feed upon earth only, but it is doubtlessly the vegetable
extract which is mixed with the mould, and which is pro-
duced by annual plants that putrify yearly, and from the
fallen leaves of others, that constitutes their nutriment,
which during digestion is taken up from the earthy matter.

b. Fresh vegetable substances.

These yield doubtlessly the most nutriment. Some insects,
as the larvae of MelolontJia, gnaw the roots of plants ; others
devour and bore into the hard stem ; to those belong the
Ptini, Anobia, and in general the entire family of Deperdi-
tora, the Cerambycina, and the bark beetles Hylesinus,
Bostrichus , Apate , &c. Others again, and by far the
majority, consume fresh leaves, for example, almost all the
caterpillars of the Lepidoptera, the larvae of the Chryso-
melina , even the perfect beetles of this family, and the grass-
hoppers. Others again, the larva of Noctua Tanaceti, Arte-
misia, &c., feed only upon the petals of flowers, many upon
pollen only and the internal parts of flowers ; very many,
lastly, feed exclusively upon ripe fruits, as the fruit moth
{Tinea [_Carpocapsa, Tr.] pomana, Pyralis pomana, Fab., or

Mem. tom. v. p. 1. pages 14, 15, edit, in 12mo.
A A 2

356

PHYSIOLOGY.

upon seeds. To these the larvae of the Curculios especially
have recourse. The Apion frumentarum and black Calandra
granaria have acquired a fearful celebrity from this circum-
stance ; the nut weevil also, Balaninus nucum, which bores
the kernel of the hazel, and the cherry weevil, Anthonomus
druparum, which devours the kernel of the sour cherry
( Prunus cerasus ), and which are frequently found fully
developed in cherry-stones, are well enough known.

II. Fluid aliments which are taken up by suction or lapping.
These are,

1. From the animal kingdom, and consist of,
a. Fresh animal juices.

These substances support the majority of toothless parasites
which are distributed upon all the warm-blooded animals.
They consist of all true lice and bed bugs, which imbibe only
blood. Some are parasites only during certain portions of
their lives, for example, the flea and the Diptera pupipara
in their last stage ; others, as (Estrus and the Ichneumons ,
only as larvae. The remarkable Rhiphidoptera also are para-
sites chiefly as larvae, for, inserted between the abdominal
segments of many wasps and bees, they project into the
abdominal cavities of these insects, but push their heads
outwardly. It is still uncertain how they feed. The perfect
winged insect appears not to be a parasite. The Ichneumons
have a similar mode of life, for they live as larvae in the larvae
of other insects, and are fed by their fat ; but subsequently,
when they are full grown, they attack the nobler organs, and
thereby kill them. The perfect winged insect sucks the
juices of flowers. Other genera, which are parasitic as larvae
upon insects and cold-blooded animals, are, in the Coleopter a,
Drilus, which is parasitic upon snails, and Symbius, Sund.,
whose larva feeds upon cockroaches. The parasitic state of
the larva of Meloe is still more remarkable, it lives upon
bees only until its first moult, and in this state has been
formed into the apterous genus Triungulinus, by Desmoulin ;
it is probable that it subsequently goes into the earth, and
lives upon the roots of plants. There is a beauty in the
almost constant law which makes the parasites of warm-
blooded animals so during their whole lives, and they there-

OP DIGESTION.

357

fore always remain apterous, whereas those of insects and
moilusca are parasitic only as larvae, and acquire wings after
quitting this mode of life. The former belong in general to
orders with an imperfect metamorphosis, and the latter to
those with a perfect transformation. The remarkable genus
Braula, discovered by Nitzsch, which most probably belongs
to the family of Diptera pupipara , and which is parasitic
upon the honey bee, makes an exception ; it is parasitic
during its whole life upon cold-blooded creatures, but is
also apterous, whereas the allied genera Hippohosca and
Ornithomya, although dwelling upon warm-blooded ones, yet
have wings. There are many other insects besides the para-
sites which feed upon animal juices, for example, the Asilica ,
which seize other insects, and by means of their long proboscis
suck out all their juices ; the Tabanica, which sting men and
animals, and derive sustenance from their blood, besides many
genera and species of the numerous family of gnats, for
example, Culex , Ceratopogon, as well as the allied genus
Simulia ; lastly, the larvae of the Dytici, which suck out
insects, like spiders, by means of their large hollow mandibles,
which are opened at their apex : the only analogy among
perfect insects to this structure of the mandibles is to be
found in the hollow proboscis of the Lepidoplera, whereas
in the spiders it is the usual and most common form.
b . Corrupt animal juices.

These are the same as those mentioned under I. 1. b., viz.,
the impure juices of carrion and dung ; they are voraciously
sucked up by many dies, for instance, Musca Caesar, Scato-
phaga putris, Scybalaria, &c., and are even lapped up by the
Coleoptera, whose oral organs are less adapted to manduca-
tion, as was fully shown in the preceding paragraph.

2. From the vegetable kingdom.

a. Fresh vegetable juices are sucked up by many insects, viz.,
the Cicada , bugs, and Aphides, as well as the .species of
Chermes and Coccus. The majority pierce young one-year
shoots, and thereby so exhaust them that they die, particu-
larly when, as in the Aphides , they are found in hosts upon
one shoot. Almost each species selects a distinct plant, and
it is frequently the case that they are to be found upon that

358

PHYSIOLOGY.

alone. The same is the case with the parasites, particularly
the constant ones, whereas those which are merely partially
so, for instance, the gnats, the flea, &c., frequent all the
warm-blooded mammalia of various families and orders. The
partial parasites of insects and the Mollusca are also found
tolerably limited to one species, or at least to but few, but
two or three. Few animals are so much restricted to one and
the same kind of food as insects. Thus the leaf-consuming
caterpillars have generally each its distinct plant, and indeed
some are so scrupulous that they reject all other plants, and
will even starve to death rather than touch any but their
usual food. Besides the crude unprepared juices which are
found in the stem the more fully developed ones of the flower
yield nutriment to many insects. All the Lepidoptera, with-
out exception, suck the nectar of blossoms, the same with the
wrasps, bees, and many other Hymenoptera, and, lastly, among
the Diptera, the Bombylodea , and Syrphodea , but they do
not restrict themselves to certain plants, but frequent all, and
those which are the richest in honey are the most agreeable to
them. Some, as the wasps, lap also the fresh juices of ripe
fleshy fruits, particularly those which are sweetened by the
influence of the sun upon a wounded part.

We may also here briefly state that many beetles, for
instance, the Lepturce , Coccviellce , &c., lap the honey of
flowers, and that others prefer the crude juices of the stem,
as Lucanus , &c. that of the oak.
b. Corrupt vegetable substances.

There are not many insects which resort to these. If we
did not here include the juices produced by the rapid putre-
faction of fungi, or the in general almost fermenting juices
of mature fungi, upon which the larvae and perfect insects of
the numerous family of Mycetophtkires feed, we should
scarcely find genera that have recourse to such nutriment.

§ 220.

The first change of the food, and which is as it were a preparation
for digestion, takes place during the mastication or sucking by the
intermixture of the secretion of the salivary glands. These organs, as
we find at § 112, are found in all haustellate and many mandibulate

OF DIGESTION.

359

insects, particularly in those which feed upon vegetable substances, they
secrete a peculiar white, frequently perfectly hyaline fluid, which appears
to be of an alkaline nature, and becomes intermixed with the food in the
mouth itself. This intermixture has a threefold purpose, namely,

1. The mechanical dilution of the nutriment. This attenuation is
the more necessary, particularly in such insects which feed upon hard
vegetable substances, from their containing very generally but little
moisture, and their comminution in the mouth must necessarily be more
difficult than when the food consists of soft animal substances. Thus
by manducation, and being mixed with the saliva, it becomes changed
into a thick pap, upon which the stomach can more easily act. The
grasshoppers, Grylli, larvae of the Capricorns , the wood borers, and the
caterpillars of the Cossus, appear especially to require this mechanical
attenuation of the food, from its generally consisting of hard wood.

2. The chemical effect of the saliva upon the nutriment is still more
apparent. The saliva, by its very constitution, is a poison which as it
were kills the food, depriving it of its natural living quality, and
thereby transforming it into a scalded state. This is proved by the bite
of poisonous serpents, whose poison is nothing else than the saliva
secreted by peculiar glands. According to Humboldt * the saliva of
serpents alone suffices to change the flesh of recently killed animals
into a gelatinous substance, and they therefore lick their prey all over
before they swallow it. The saliva of insects has a similar effect.
Immediately after swallowing and the intermixture with the saliva in
the mouth, the green leaves upon which caterpillars feed lose their
bright colour and acquire by degrees a darker dirty colour, resembling
that of boiled vegetables. The puncture also of blood-sucking insects
convinces us, most distinctly, by the pain of the wound, of the corrosive
effects of the saliva, and the inflammation attendant upon it, of its
transforming power.

3. The dynamical effect of the saliva, under which we understand its
faculty of changing the food into that state that the requisite nutri-
mental substances can be separated from it. It therefore requires no
further proof, for it is evinced by too many experiments that the saliva
does not always act in the same way, but that its effects are different ac-
cording to the differences of individuals ; consequently a variety of insects
may feed upon the same materials and yet produce very different effects

Ansicht der Natur, tom. i. p. 141.

360

PHYSIOLOGY.

from the action of the saliva and the other fluids which flow into the sto-
mach: for example, the true Cantharides ( Lytta vesicatoria) and Sphinx
Ligustri feed upon the same plant, viz., Ligustrum vulgare , Lin., and
yet in the Sphinx we do not find the least trace of the blistering prin-
ciple which so greatly distinguishes the Spanish fly. And this is
peculiar also to other species of Spanish flies, which however feed upon
very different plants, and in the most distinct climates. With respect
to the puncture of blood sucking insects, everybody knows the differ-
ence of its effects from different insects. The puncture of the bed bug
(Acanthia lectularia , Fab.) leaves behind it a small, whitish, projecting
swelling ; that of the flea a spot made red by the wound, but which is
not painful. The puncture of our water bugs is painful; for example,
the Nolonectce, Naucoris , and Sigara, the pain of which must espe-
cially be attributed to the saliva which is inserted in the wound. This
is the case also in the puncture of the common gnat, for the mechanical
injury is too trifling to produce such sensible pain. How very different
however is the inflammation after the puncture of this creature than in
the before named insects. The difference in tropical insects is still
greater. St. Pierre, in his voyage to the Mauritius, relates an instance
of a bug whose puncture produced a swelling of the size of a pigeon’s
egg, which lasted five days *. The large exotic Tabani also cause
severe inflammation by their punctures, as Kirby and Spence have shown
in an instance ; with us also the species of the genera Chrysops and
Hcematopota, of the family of the Tabani , make painful punctures.
The sting also of the smaller genera of Culices are sometimes very
painful, as that for instance of the notorious Simulice , particularly when
they attack man and animals in hosts ; by the multitude of their stings
they then set the skin in such an inflamed state that it produces severe
illness, which frequently terminates in death. The same may be said
of the mosquitos, which are small Culices that belong probably to the
same genus, and which between the tropics are complete pests by
reason of the intolerable itching produced by their punctures. The
anthrax, or pustula maligna, which has been occasionally observed to
arise after the puncture of an insect is scarcely to be considered as the
consequence of its mere puncture, but of a poisonous lymph that has
probably still adhered to the proboscis of such a fly, which immediately
before may have punctured a diseased animal. The puncture therefore

Kirby and Spence, Introduction, vol. i. p. 171.

OF DIGESTION.

361

of a particular species of fly cannot be considered as the cause of this
malady.

These three different qualities of the saliva do not present themselves
separately, but more or less contemporaneously. The vegetable fibres
are by its admixture softened and loosened, then chemically changed
and made tender, or, as it were, scalded, and, lastly, by its intimate
incorporation it is rendered fit for assimilation and digestion. After
this preliminary change a second comminution takes place in the crop
when this organ exists. We consequently find among the mandibulate
insects salivary glands only in such species, genera, and families, which
are more or less strictly herbivorous, for example, the grasshoppers,
Grylli , Termites , and they are entirely deficient in the carnivorous
ones. In them the larger quantity of gastric juice that is secreted
supplants the function of the saliva, whence it is that their intestine
beyond the crop is beset with a multitude of blind, doubtlessly gland-
ular, appendages ; and even if such appendages are found in the herbi-
vora, for example, in the grasshoppers and others, they are fewer in
number and smaller in size. Where both salivary vessels and these
appendages are wanting the long stomach is then entirely covered
with glands, as in Hydrophilus. In haustellate insects the saliva
attenuates the imbibed juices and becomes intermixed with it in the
process of sucking. Thus in the bees the salivary duct opens into the
same duct through which the honey is sucked ; in the Lepidoptera,
through the central canal which is formed by the union of the two
probosces, and it drops down out of this channel whilst the insect is
sucking. Reaumur and Treviranus have both seen it fall in drops.
In the Hemiptera and flies it also opens into the proboscis, probably
here also, as in general, beneath the tongue ; by means of it the hard
setae are kept constantly lubricated, which facilitate their reciprocal
motion. It is also intermixed with the imbibed nutriment in the
mouth, it kills and scalds it, and thus prepares it for digestion, which
then next takes place in the long or subdivided stomach. In the
Cicada and bugs, the majority of which imbibe crude vegetable juices,
this preparation for digestion is of considerable importance, and we
therefore find in them very large salivary glands.

§ 221.

The remaining function of digestion, subsequent to manducation and
the intermixture of the saliva, is exhibited less uniformly in insects than

362

PHYSIOLOGY.

the functions just indicated. The most striking differences have already
been exhibited in the remarkably divaricating form of the stomach.
These divarications admit of being, as well as their functions, classed
into the following three chief heads : —

A. The digestion of firm, partly animal, partly vegetable sub-

stances. These take place,

a. By the aid of a crop,

b. Without a crop.

B. The digestion of liquid substances always takes place with-

out the assistance of a crop.

The form of the intestinal canal is thence adapted as far as the
opening of the biliary vessels., and we therefore find

In the first case a crop, a proventriculus, and a stomach, but which
we shall call henceforth the duodenum, as it corresponds in function
with that organ of the higher animals. In a thus formed intestine the
hardest animal and vegetable substances are digested.

In the second case, in which the proventriculus is wanting, the crop
and duodenum are united in a single narrow and equally wide tube,
which may be here properly called the stomach. We find this stomach
in all insects which feed upon light vegetable, or even corrupt pappy
animal substances. Sometimes this entire stomach, like the duodenum
of the carnivora, is throughout shaggy.

In the third case a true proventriculus is indeed wanting, but we
sometimes observe an analogous form. These are wholly deficient in
the Lepidoptera ; their small oval food bag is both stomach and duo-
denum, and the crop is changed into the sucking bladder. In cater-
pillars the long, broad, cylindrical stomach is likewise stomach and
duodenum, but the crop is wanting. The same is the case in the
Diptera. but the stomach, together with that portion of the intestine
forming the duodenum, is very long, round, and tubular. The Hymeno-
ptera have a wide crop, which serves as a sucking stomach, a funnel-
shaped orifice to the stomach, which represents the proventriculus, and
a tolerably long transversely ridged duodenum. The Hemiptera,
lastly, exhibit again all three divisions, but in these they are more
widely separated : the crop is the first broad, purse-shaped stomach ;
the proventriculus we again find as a thin but compact muscular tubular
second stomach ; the duodenum is thus in the Cicadaria the narrow,
but in the bugs wider, transversely ridged, third stomach, which is
furnished with auxiliary ducts. If but two stomachs are present the

OF DIGESTION.

363

middle one, or proventriculus, is wanting. Thus the chylifying por-
tion of the intestine is formed in the several orders according to the
differences of their food ; for greater detail I refer to § 105.

If we now investigate the digestion of solid substances by the assist-
ance of the proventriculus we shall find that those, when of the animal
kingdom, are swallowed wholly unchanged but in pieces, but, when
of the vegetable kingdom, they are already much comminuted and
intimately mixed with the saliva. They consequently first arrive at
the large crop placed in front of the proventriculus, which in some
cases, as in the Dytici , is thickly beset internally with glands, and the
superior surface of the internal tunic is occupied with wrinkles, horny
lines, and teeth (PI. XVII. f, 5 — 7-)* The secretion of these glands,
is a dark brown sharp corrosive fluid, which strongly smells like Russia
leather, it supplies the place of saliva, envelopes the food, makes it soft, and
thus prepares it for digestion. The food, after having thus remained
a short time in the crop, advances by degrees into the infundibuliform
orifice of the proventriculus, and thence into its narrow cylindrical or
star-shaped cavity, where it is easily comminuted, and transformed into a
uniform pap-like consistency. To produce this we observe in the crop, and
particularly in the proventriculus, a peculiar motion, which consists of
an alternating expansion and contraction. This contraction commences
at its anterior extremity, and gradually advances to the end of the
proventriculus, whilst the earlier contracted portion again expands. It
thus greatly resembles the progressive advance of worms and footless
larvae; it is called the peristaltic motion. It is most distinctly observed
in the proventriculus, which also, of all the parts of the intestine, is sup-
plied with the largest fasciculi of muscles (§ 104), and it here appears
as a contraction and distension of its internal cavity, produced by its
rhythmical contraction and expansion. By means of this contraction
the teeth and horny plates rub against each other, and thus grind the
food into a simple uniform pap, which is called chyme. In this state
we then find it in that portion of the intestine lying behind the
proventriculus, which, as we have above seen, is supplied throughout
or partially with short blind appendages. These appendages, according
to Rengger *, become shortened when the intestine is filled with food,
and they then appear merely as lumps upon its surface. Its contents is

* Physiologische Untersuchungen über den Thierischen Haushalt der Insekten.
Tubing. 1817. Bvo.

364

PHYSIOLOGY.

a thick pappy mass, which melts by the addition of acid, and on the
application of heat, it is found in the blind appendages as well as
in the cavity of the canal. It is of a white colour, and is thereby
distinguished from the brown nutriment found in the crop. Ramdohr
and the earlier entomotomists call this division of the intestine, behind
which the biliary vessels open themselves, the stomach ; according to
Treviranus, Joh. Muller, and Straus Durckheim on the contrary, it
should be called duodenum t* This last opinion is doubtlessly the
most correct, for the whole business of chymifaction is already over
when the food arrives at this portion of the intestine, and the formation
of chyle commences here. The resemblance of the crop to the anterior
stomach, and the proventriculus to the muscular stomacli of birds, is so
striking, that the similar situation of that portion of the intestine behind
the muscular stomach would oblige us to consider both as analogous
forms, even were all other resemblances wanting. The chief difference
however is, that the biliary ducts do not, as in the birds, open into this
division, but behind it ; but in lieu of which other secreting organs,
which are the equivalents of the pancreas, namely, the blind append-
ages, are found around its entire circumference. Rengger does not
consider these appendages as secretory organs, but as pockets, whence
the lacteal juice is more readily passed into the ventral cavity, and
because chyme is also found in them ; but that is also found in the
pyloric caecum of fishes. Their abbreviation, however, upon the filling
of the intestine, is not an objection, but it merely proceeds from the
necessary distension of the intestine produced by the accumulation
of more matter. Another reason, however, for not considering that
division of the intestinal canal lying behind the proventriculus as the
stomach, is the deficiency of a peculiar nerve in its vicinity. The
nervus sympathicus descends, we know, from the brain to the pharynx,
and distributes itself upon the surface of the crop, with several branches
and ganglia, similar to the web of the superior animals. But if there
be a proventriculus the branches of the nerves suddenly cease in
its vicinity, and that portion of the intestine lying behind the pro-
ventriculus receives none ; but where the proventriculus is wanting the
nerves are distributed only at the anterior portion of the stomach, and
the posterior part which corresponds with the duodenum receives none

* See above, § 105.

•f The true duodenum of insects is the villose stomach, or, where thisf'is wanting, the
long tubular stomach itself.

OF DIGESTION.

365

either. These nerves, however, are a main condition of digestion, and
they present themselves, especially, at the stomach and anterior stomach,
because it is the most active portion of the intestine in exercising the
function of digestion. Both comminute, especially the pro ventri cuius,
the remainder of the intestine absorbs: a considerable interruption of the
function of digestion has consequently been observed in the superior
animals upon the scission of this nerve.

In those insects which possess no proventriculus the digestion of the
food is effected less by comminution than by the gastric juice found in
the stomach. It also appears to be of an alkaline nature, at least
Ramdohr observed a fermentation upon the application of acid, and
according to Rengger it stains litmus paper of a brown red ; and according
to the former it also turns paper blue which has been previously
stained red by an acid. Rengger’s experiments upon the caterpillar of
Deilepkila Euphorbia most distinctly convince us of the purely che-
mical and dynamical transformation of the food in the stomach. The
form of the small bitten pieces of the leaf remains unchanged, but they
were somewhat loosened, and they appeared at the lower portion of the
stomach to have lost substance. The fluid contained within the stomach
was stained green by their extract. In other caterpillars, for example,
that of Pontia brassica, the chyme appeared more comminuted and
more pappy, doubtlessly because the substance of the leaf of the
cabbage is more juicy, softer, and more decomposable than that of the
Euphorbia. The separation and absorption of the chyme is promoted
by the constant peristaltic motion of the stomach : this motion inti-
mately intermixes the portions of the food, and gradually subjects them
equally to the action of the gastric juice secreted by the glands of the
stomach, and it partly helps to move the food from the anterior to the
posterior extremity of the stomach. It is here that the elaboration of
the food has attained its highest point, and it is therefore here that it
least resembles its original quality; it has here become darker and
browner, whereas it was originally of almost the same colour as that of
the leaf of the plant. But the mechanical advance of the food is not
however wholly owing to the peristaltic motion, but it also depends upon
whether fresh food^has been received. When this is not the case the
whole process of digestion appears more slow ; the food already in the
stomach then remains there, but becomes gradually softer and looser,
and loses its colour, and appears decomposing ; at least, according to
Rengger, it then smells very unpleasantly ; it also gradually loses the

366

PHYSIOLOGY.

fluid portion of tlie chyme. But if the period of fasting be too much
prolonged the caterpillar dies, and the food is even then found in
the stomach. In general voracious caterpillars, which usually consume
daily three times their own weight of food, cannot fast very long, at
least not more than eight or ten days ; perfect insects, namely, some
beetles, can do without food much longer. I myself have seen a Blaps
mortisaga move about quite briskly after having fasted for three entire
months. Other instances have been observed in capricorn beetles
which have been enclosed in wood for years ; they were in a torpid
state, but revived upon being exposed a short time to the air. Pre-
daceous beetles, such as the large Carabi and Dytici, cannot long fast,
at most a few weeks. Caterpillars which are not fed after their last
moult do not die, but change into pupae, but the pupae are easily killed,
particularly if the caterpillar immediately after moulting has been
deprived of food ; but the voracitv of caterpillars decreases with the
increase of their age, and it is only during the first period of their
existence that they exhibit a hunger which is almost without parallel.

Many beetles, viz., the Carabi , the grasshoppers, and the larvae of
the Lepidoptera, eject upon being touched a brown, corrosive, gastric
juice, and cast it at their enemies. Whoever has collected insects, and
especially the Carabodea, must be well acquainted with this mode of
their defence, as also with the pain which the intrusion of it occasions
when by accident, which is not rarely, it comes into the eye. This
acute pain, which occasions a gush of tears, distinctly proves the
sharp and caustic quality of the gastric juice. In some Hymenoptera,
namely, in the bees and wasps *, the ejection of the food regularly
takes place, for they cast up, farther elaborated, the imbibed nectar of
flowers, and supply the young with it as food. The ejection of it is
caused by the antiperistaltic motion of the stomach and proventriculus,
and thus the gastric juice is passed into the mouth by a contorted
motion of the animal, whence by another quick bending it is thrown
from it. According to Rengger the muscles of the skin also contribute
considerably to the retrograde motion of the stomach, at least the force
was considerably diminished when he cut the caterpillar along the back,
and then irritated it by pressing and tormenting, causing the ejection
of its saliva. In many, the innermost tunic of the stomach, after great

* Spallanzani Versuche über die Verdau ungsgesch, p. 36. Reaumur, Mem, del’ Acad,
des Sc. dc Paris, A. 1752, p. 472.

OP DIGESTION.

367

efforts was throwu np, whereupon the caterpillar died. After this, air
in the shape of bladders broke out. This air appears to be constantly-
found in the stomach during digestion, and is probably partially
swallowed with the food, and is partly evolved from the food in the
stomach. The first takes place, according to Rengger, that the gastric
juice which is spirted forth as a defence may be the more easily ejected,
yet the constant biting and swallowing small pieces of leaves necessarily
occasions the passage of some air into the stomach. During the pupa
state, the intestine contains only air, or even nothing : we also find in
perfect insects, for example, in the Ephemera , Libellulce, Grylli , &c.,
much air in the stomach and the whole intestinal canal.

The digestion of fluids which haustellate insects imbibe, takes place,
doubtlessly, in the same manner as the firmer manducated nutriment,
with the alterations only which arise from the difference of food. The
more elaborated the juices are, the more simple is the structure of the
intestinal canal, whence it follows that the digestion of the nectar of
flowers takes place in the Hymenoptera in a single cylindrical, but
compact, transversely ridged duodenum, whence the chyme, together
with the addition of the secretion of the many biliary vessels, passes
into the true ilium. In the bugs, this simple duodenum, as the above
description of their digestive apparatus (§ 105) has shown, is separated
into several intestinal divisions, the first of which corresponds with the
crop, the second with the proventriculus, and the third with the true
duodenum. In addition to this great perfection of the chymifying
portion of the intestinal canal, we must include the long and multi-
farious salivary vessels as preparatory organs, which very much facilitate
the progress of digestion by the contribution of their secretion. The
juices are thereby made capable of assimilation, and the assimilating
portion is absorbed by the parietes of the ilium. It arises thence, also,
that that portion of the intestine which lies beyond the duodenum is,
at least in the bugs, extraordinarily short, whereas in the Hymenoptera
and in the flies it is of the same length, or, as in the Lepidoptera , even
longer. The smallness of the stomach connected with the duodenum
in the Lepidoptera , makes us surmise that they take but little, or,
indeed, many of them in their perfect state no food at all, or that,
as their food consists of the nectar of flowers, it requires but little
change. Thence their small stomach and long narrow ilium ; and,
next to the saliva, the secretion of the biliary vessels may contribute
considerably to the transformation of this honey. Among the Coleopter a

368

PHYSIOLOGY.

we find a family which agrees entirely with the Lepidoptera in requiring
but little food, viz. the capricorn beetles. They also, as beetles,
probably eat but little; at least, in all those individuals that I have dis-
sected, I found the intestine full of air ; and their nutriment likewise
consists of the delicate nectareous juices of flowers. But of all
haustellate insects the Diptera are the most voracious : we observe
them the whole day long lapping and tasting every possible substance
which contains sweet juices, or such as are agreeable to their palate, and
which are frequently nauseous and stinking. They have consequently
the longest duodenum of all insects. In front, where it supplants the
stomach, it is most compact and muscular ; behind it is softer, more
delicate and membranous. The food is received into this long intestine,
and, as it is generally of a cruder nature than that of the Lepidoptera ,
it consequently requires several different elaborative fluids. We there-
fore find, besides the oral salivary glands, others which sink into the
commencement of the duodenum.

§ 222.

The elaboration of chyle takes place even in the first portion of the
intestine, which corresponds in situation with the stomach and ilium,
or where a proventriculus is found only in the -duodenum lying behind
it. The chyle is a whitish or greenish or even brownish, thick liquid,
which first presents itself as a flocky substance between the innermost
and second tunics of the stomach, and, upon a microscopic inspection,
appears to consist of minute globules. It is the produce of digestion and
the object of all the functions of the intestinal canal, and it forms the
foundation of all the other nutritive fluids. In the higher animals, the
chyle is therefore absorbed by the lymphatic vessels placed along the
intestine, and conducted into the venous blood, whence it passes into
the lungs or gills, here becoming oxydised, and it is then poured forth
by the heart as fresh arterial blood. But such a circulation of the
juices is not found in insects, for they have neither absorbents nor veins,
but merely a single arterial vessel placed along the back. If, therefore,
the chyle or lymph is to pass into this vessel, it must be transmitted
through the parietes of the intestine and pass through the cavity of the
stomach, whence the heart receives it through the above- described
valve. This passage of the chyle through the intestinal tunic
observation has distinctly detected. Ramdohr saw the chyle which
was contained between the mucous membrane and the true skin forced

OF DIGESTION.

369

during the peristaltic motion of the stomach through the exterior
muscular tunic, and the remainder, which was not thus passed through,
was driven towards the end of the stomach, and here distended the
exterior tunic in the circumference of the pylorus. In a cockchafer,
whose longer ilium was filled only at certain parts with food, he
observed, after the stomach was removed from the body, a continued
distending of it at those parts where the food was found. Upon opening
the external skin at those parts, the brownish green chyle streamed
forth. Rengger also observed the transmission of the chyle through the
intestine in larvae, which he opened alive, for, having carefully dried
the exposed stomach, he saw it speedily become again moist.

Upon the chemical inspection to which Rengger subjected the chyle,
that he found between the tunics of the stomach, it did not exhibit
the alkaline property of the saliva and the gastric juice. In weak
acid it formed flocks, as also when exposed to heat, which was dissolved
in concentrated sulphuric acid ; but, upon the addition of water, it re-
formed flocks. He found similar flocks when he caused the caterpillar
to vomit into diluted acid. Hence it appears that the chyle consists
chiefly of albumen, which appears to be suspended in water. Rengger s
experiment further confirms this opinion, for he injected water into the
stomach of a caterpillar after he had tied up its end, and, upon opening
it after a short time, he found the chyle at the anterior end much more
full of water than that of the posterior, of which he convinced himself
bv the coagulation of the albumen by heat.

From the chyle being transmitted through the tunic at that part of
the intestine usually called the stomach, is another reason for not
considering it the stomach only, for the chyme alone is prepared in the
stomach, from which the chyle is separated in the duodenum and ilium.
We must, therefore, consider this portion, as in the lower animals,
merely as the simple internal digestive cavity, whence gradually, by
metamorphosis, different intestinal parts are produced, which present
themselves as the crop, proven triculus and duodenum ; or where such a
division of the simple cylindrical nutrimental canal is not found, that
that insect has remained stationary upon a lower grade of the organisa-
tion of the digestive apparatus. We should thus find within this single
class a progressive succession of the perfection of the intestinal canal,
for, commencing with the bag of the larvae of the bees, which has no
anal aperture, it terminates in the perfect structure of the predaceous
beetles, and which corresponds distinctly with the development of the

B B

370

PHYSIOLOGY.

nutrimental canal throughout the animal kingdom. They thus repre-
sent in their crop and proventrieulus the form of the canal of birds,
and by means of the blind appendages of the duodenum they are like-
wise connected with the fishes.

§ 223.

In all the higher and in many of the lower animals, namely, the
Mollusca , the formation of the chyle is produced by the addition of a
peculiar fatty alkaline fluid, namely, the gall, which is secreted by a
large lobate gland, called the liver, the duct of which empties itself
into the duodenum, sometimes behind the pylorus, but in general in the
vicinity of the opening of the ventral salivary glands. The object of
this fluid appears to be to decrease the acidity of the chyme, and
then by the intermixture of its component parts to prevent a preju-
dicial corrupt decomposition of the food upon passing through the
intestinal canal ; to transmit the fat in suspension, in which it is more
readily absorbed ; and to assimilate the nutriment by means of the gall
and other animal matters it contains ; and lastly to stimulate the peris-
taltic motion *. We may now ask if an analogue of these glands is to
be found in insects, and whether its secretion when it exists is of such
influential effect as the gall in general.

With respect to the existence in insects of such glandular secretory
organs which empty themselves into the intestinal canal, we may
observe, that but one kind of them is found, which is peculiar to all
excepting Chermes and Aphis, and this is the above described (§ 111)
biliary vessels. All other secreting organs which are found in the
intestine of insects are peculiar to certain orders and families only.
We have characterised them above as salivary organs, and given a
detailed account of their form and presence (§ 112).

These gall vessels are actually gall-secreting organs, according to
Cuvier, Pusselt, Ramdohr, Carus, and the earlier opinions of Treviranus
and Meckel. This opinion may be supported by

1. The general form of the secreting organs in insects.

2. By their situation, and by their insertion in the intestinal canal
corresponding with that of the gall-secreting organs of other
animals.

* Gmelin’s Theor. Chimie, vol. ii. part ii. p. 1517. The result of the comprehensive
experiments of Tiedemann and Gmelin upon digestion.

OF DIGESTION.

371

3. That at the spot where they empty themselves into the intestine
there is frequently a bladder-shaped distension, a kind of gall
bladder (for example, in Lygceus apterus , Cimex baccarum ).

4. That sometimes, as in the secretory organs of other animals,
stony concretions are found.

5. That they are very compact, and wholly surrounded by the fatty
substance which is the formative matter whence all secreting organs
derive the fundamental portion of their secretion. ~

6. That also the vena porta which conducts the blood to the liver in
the higher animals takes its rise from such a fatty matter distri-
buted within the ventral cavity, viz., from the mesenterium.

7. That the liver of the most closely allied animals, namely, of the

crabs and many annelides (for example, Aphrodites ), consists
likewise of such blind vascular appendages which empty them-
selves into the intestine. .

Whereas these opinions are contradicted by those of modern na-
turalists, namely, of Herold, Rengger, Straus Durckheim, Joh. Müller,
and by the altered views of Meckel * and Treviranus + upon the follow-
ing accounts : —

1 . The biliary vessels empty themselves at a part of the intestine
beyond where the chyle has been commenced to be absorbed,
frequently closely before the colon, a short distance from the anus.

2. The chemical analysis of the biliary vessels, and of their con-
tents, exhibits but little resemblance between it and the liver,
for uric acid is its chief component. According to Chevreul’s
analysis J, the liquid obtained from the biliary vessels was alkaline,
and vegetable colours, which had been turned red by acids, it
stained blue ; and upon the further addition of acids it precipitated
uric acid, and smelt of ammonia when a weak solution of caustic
potass was added to it. He thinks, therefore, that this liquid holds
urate of potass and ammonia in solution. Wurzer§ found also
urate of ammonia, and both phosphate and carbonate of lime, which
Brugnatelli || and John equally found also in the excrement of
Lepidoptera immediately after their exclusion from the pupa.

3. Besides these biliary vessels many insects have other secreting

* Archiv, fur Anat. u. Phys. Jahrg. 1826.
f Das organische Lebens neudargestellt, p. 335. £ Straus Durk., p. 151.

§ Meckel’s Archiv., iv. p. 213. || lb., p. 629.

B B 2

372

PHYSIOLOGY.

organs which empty themselves into the intestine, even indeed in
front of the chylifying portion of it, namely, those blind append-
ages indicated as salivary glands behind the proventriculus.

4. In the spiders, secreting organs which resemble the biliary vessels
empty themselves into the colon ; and other vessels, which are in
close connexion with the fatty matter, open into the ilium, and
supplant the liver.

To harmonise if possible both views, which then would be the only
true and correct one, we must in the first case ascertain if the liver,
considering the organisation of insects, be absolutely necessary to their
digestion. We find the liver large and of prominent development in
all such animals in which the function of respiration is of diminished
importance, especially those mollusca which breathe through branchiae,
and the fishes *. If we may thence conclude that animals which
respire by means of lungs have a smaller liver, it is evident that insects,
as those animals in which the respiration by means of lungs, or rather
of pulmonary air-tubes, has attained its highest grade of perfection,
must necessarily have the smallest liver of all. This may be caused
by, as Carus f has remarked upon a similar occasion, the lungs and
liver both separating the same substance, namely, such which contain
carbon, by the former from an elastic fluid, and by the latter from a
liquid. If, therefore, the lung is so predominant that it is found
throughout the body, this separation takes place everywhere, and the
liver, which by means of the veins receives the carbonated blood from
the different parts of the body, where there is no lungs, is not required
to act. The function of the liver as an excretory organ is therefore
not requisite in insects, but yet as a secretory organ it is still of
importance. Its chief object, viewed thus, is to reduce the acidity of
the chyme, by means of the alkaline property of its secretion ; but we
have seen that the secretions of the salivary glands, and of the pro-
ventriculus, are both alkaline, and that the chyme beyond the pro-
ventriculus, or at the end of the duodenum, is perfectly neutral, and
requires no addition of alkali to neutralise it ; consequently even for
this purpose the function of the liver is not necessary.

If we have thus shown that insects do not require a liver to promote

* This reciprocal relation appears to me as confirmed, and worthy of consideration,
whereas the meritorious G. R. Treviranus denies it. Biologie, tom. iv. p. 420.

*)* Bootomie, p. 538.

OF DIGESTION.

373

digestion, it may be asked what is the function of the biliary vessels ?
Are they urinary organs or kidneys ? Certainly not ; for where shall we
find, throughout the whole animal kingdom, an instance of the ureter
emptying itself into the middle of the intestinal canal? And is not this the
case with the biliary vessels in many, indeed the majority, of instances ?
The uric acid which chemists have found therein proves nothing, for
many parts of the body of insects contain this acid, as Rudolphi * also
correctly observes, it islikewise found in many other fluids besides urine f.
Lastly, the resemblance of the biliary vessels to the urinary organs is
too trifling, and the latter are always in closer connexion with the
sexual organs than with the intestinal canal ; besides, in some insects,
namely, in the Carabodea , Dyiicl , and Staphylini , distinct urinary
organs have been found (§ 113), the secretion of which indeed has not
yet been proved by analysis to be urine, but which, both by their resem-
blance in form, and partly by their situation, have proved themselves
urinary organs. Joh. Müller X, who has most strongly supported the
consideration of the biliary vessels as kidneys, will not admit of these
organs being considered as secreting urine, but explains them to be
peculiar glands which secrete a sharp liquid, and compares them with
the poison glands of the Hymenoptera ; but even if we admit of this
analogy we must yet oppose his assertion that the insects which are
provided with these organs secreting a sharp liquid, for it is supported by
no other observation than at most the explosion of the Brachini. As
this exploding secretion is gaseous, it cannot necessarily be secreted by
these organs, but may be merely be the air contained within the broad
colon. Whereas the Dytici , upon being seized, as I have frequently
observed, eject their hyaline livid urine, which has a peculiar pungent
smell, very like feverish or corrupt human urine, but which never
acts acutely or poisonously, and inflammatory. We may here justly
ask why these few insects only have urinary organs, and the majority
want them, which is absolutely a difficult problem to solve ; but
in some others, for example, Bombylius , Leplis, the same organs are
again found, and in Gryllus migratorius, Fab., I observed a single
serpentine vessel, which originated from a small kidney-shaped organ,
and which opened at an analogous spot near the anus. It is therefore

* Physiologie, vol. ii. part ii. p. 145, note 1.

f Gruel. Handb. d. Th£or. Chemie, vol. ii. part ii. p. 1473

£ De Gland, secern, struct, pen., p. 68.

374

PHYSIOLOGY.

probable that in the other grasshoppers such vessels will be found, as
well as in other voracious insects, which, as such, more require excretory
organs ; whereas in temperate insects, and such as feed upon highly
elaborated finer substances, as well as haustellate insects from the
greater preparation of their food, and its consequent perfect quality of
assimilation, the excretory organs would be wholly superfluous. Where-
fore then, it might be objected, have the voracious caterpillars and
larvae no urinary organs? To which we might reply, that it must not
be forgotten that larvae stand upon a much lower grade of animal deve-
lopment than perfect insects, and that they therefore do not display so
great a separation and division of their organs ; if the anus be wanting
in some instances, how much more likely are the urinary organs to
be deficient ? and, besides, the majority of caterpillars have other
excretory organs, viz,, the spinning vessels, which take up from the
body much useless matter. The unimportance of the urinary organs to
the nutriment of larvae explains their deficiency in those cases in which
the beetle exhibits them ; at least in the larva of Calosoma sycophanta
I have not observed such organs.

If, then, the biliary vessels be neither exclusively liver nor exclusively
kidneys, it remains to be determined what their function is. To arrive
at this we look around us for analogous forms in other animals, and
immediately discover the paired caeca of birds. These organs, which
Carus* even wished to compare to biliary vessels, diverge in one
respect by their frequently considerable shortness (for example, in all
the diurnal birds of prey), and in a second respect by their contents
differing so much from that of the biliary vessels of insects ; they are
also of a similar structure with the intestinal canal, which is not the
case with the biliary vessels. But it is remarkable that the parallel
orders of birds and insects exhibit some approximation in the length of
these organs, for the biliary vessels are likewise very short in the car-
nivorous Carabodea , and if not exceedingly long yet they are very
numerous in the herbivorous grasshoppers and Grylli, which I com-
pare with the gallinaceous birds, into the detail of which I shall go
below. We might therefore indicate, if not a strict analogy, at all
events a certain approximate relation between these appendages of
the intestinal canal.

Besides these paired caeca of birds we find no other appendages to

* Zootomic, p. 388.

OP DIGESTION.

37 5

the intestine in animals which admit of being compared with the
biliary vessels, unless it be precisely the same forms in the Annelides
and Crustacea. These have been, particularly in the Crustacea, ex-
plained as the liver, and therefore the biliary vessels must be consi-
dered as the analogues of these filaments, or at least, as the analogues
of the liver. With respect to form, this is doubtlessly correct, the above
cited reasons speak too clearly in favour of it ; but in function they
are not merely liver, indeed not purely secreting organs, but more
justly excretory organs, which, however, do not separate urine alone,
but also a kind of gall, and only in those instances where true urinary
organs are wanting undertake as well the function of urinary organs.
With respect to what may be objected from their opening higher
into the intestinal canal, we may reply, that probably the whole re-
maining portion of the intestinal canal absorbs but little chyle, but
instead, as Joh. Müller also considers, leads off the unassimilating
remains. But in those instances where there are actual urinary
organs the biliary vessels may be exclusively liver, at least their
darker brown red colour in all these cases speaks *in favour of it, par-
ticularly in the Carabodea and Dytici. In these then the tolerably
long and especially broad and muscular ilium must also separate chyle.

I therefore positively consider the biliary vessels as analogues in
form of the liver, but which do not exclusively exercise the function
of the liver, but conjunctively, at least in mapy cases, the function of
the kidneys, and of other secreting organs.

An opinion propounded by Oken explains the fatty substance as
liver, but it is inapplicable, as has been shown by Meckel. Yet we
cannot deny that the fatty substance has some relation to the liver,
for the organisation of the Araclinidce speaks distinctly in support of
it. The biliary vessels may also, when they secrete bile, derive the
foundation of their excretion from the fatty substance only, and we
therefore find them everywhere closely enveloped by this fatty sub-
stance.

With respect to the direct observations of some physiologists, besides
those already cited, upon the function of the biliary vessels, we find,
according to Rengger, that they contain a clear fluid, in which the mi-
croscope detects a great number of globules. This fluid appeared more
transparent and brighter when watery substances were received into the
intestinal canal, and he therefore supposes that it is the water separated
from the blood. He then observed the fluid, upon jiressing the vessels.

37 6

PHYSIOLOGY.

pour itself into the intestine, and Meckel remarked the same, whereby
Ramdohr’s opinion is contradicted of the frequent emptying of the
biliary vessels into the space between the mucous membrane and the
true skin. He further remarked, after this emptying, a refilling of
the vessel and an advance of the fluid, without detecting the least
motion in the vessel. The substance thus emptied he says he found
again in the excrement, in the form of little globules upon its surface ;
also the reddish brown juice ejected by the Lepidoptera immediately
after their exclusion from the pupa, consists chiefly of the excrement of
the biliary vessels. That this fluid, as well as the excretion of the
biliary vessels, contains much uric acid, has been proved by the
analysis of Chevreul, Brugnatelli, and John, and which we have
mentioned above. According to Rengger, the secretion of the biliary
vessels dissolves neither in hot nor in cold water ; it becomes firmer in
alcohol, dissolves in concentrated acid, and is precipitated from this in
a flocky form, upon the addition of water : upon proof paper it exhibits
itself neither as acid nor alkaline, nor does it taste bitter, but insipid,
like all the parts of a caterpillar. The excretion does not either re-act
upon diluted chyme, and in the chyme from the intestinal canal beyond
the biliary vessels, there was no fluid matter.

Straus Durckheim considers that there are in the cockchafer two
different kinds of vessels which empty themselves into the intestines.
The anterior ones which open beyond the stomach have ramose, trans-
verse continuations, and are brownish ; the posterior ones, whose
orifices* he could not discover, are of a yellowish white and smooth,
and without continuation. The anterior ones he considers as biliary
organs, and the posterior ones as urinary organs. It is unimaginable
how Straus, in so laborious and accurate an inquiry, should make such
a mistake, particularly as two anatomists before him had described and
figured the intestinal canal of the Melolontha vulgaris, namely,
Ramdohrf and Leon Dufour |. From both, as well as from Suckow’s§
representation, it results, that in the cockchafer, likewise, there are but
four very long biliary vessels, which pass into each other, and which
at their anterior half send off ramose appendages, whereas posteriorly
they have none. That the biliary vessels in many cases, for example,

* P. 270. + Abhand, über die Verdauungsorgane, PI. XVIII. f. 1.

| Annales des Sciences Natur, t. iii. p. 234, PI. XIV. f. 4.

$ In Heusinger Zeitschrift, f. d. o. Phy. vol. iii. Pt. 1. PI. III.

OP DIGESTION,

377

in the Capricorns , stand in connexion with the intestine at a second
lower spot, but do not again open into it, has been shown above (§ 111).
Job. Müller has been misled by Straus to speak likewise of double
vessels, which, he says, open at different parts of the intestine *, but
such second vessels are not found in any insect.

§ 224.

The divisions of the intestinal canal which lie beyond the orifice of
the biliary vessels, and which we have described above as the ilium,
clavate intestine, caecum, and colon, occupy a portion of the intestinal
canal, which, in the majority of cases, is not half the length of that of
the preceding part, and which is indeed often, namely, in the Hemiptera,
so short, that it does not form one-tenth of the entire intestine. With
respect to the law which regulates the proportions of the parts of the
intestinal canal, we may consider that it is in general longer in
carnivorous insects, but, on the contrary, shorter in the vegetable
consumers, and that the larvae have almost always, with the exception
of the larvae of the Dytici , as was remarked above, a very short portion
of intestine beyond the orifice of the biliary vessels, whereas in the
perfect insect it is longer.

If we inspect the contents as well as the function of this portion of
the intestine in vegetable-feeding insects, for example, in the larvae of
the caterpillars, we shall find, according to Rengger’s observation, that
no further peristaltic motion is detected in it, and that the chyme con-
tained within it separates no longer any chyle, nor, indeed, is any mixed
with it. In the larvae of the Lamellicornia , no food is observed in the
ilium, but the great gut is closely filled with it. This nutriment is
found here further comminuted and more pappy than in the stomach,
differing in about the same proportion as the chyme of the stomach does
from that of the caecum in the Rodentia, and we must, therefore, at
least in this instance, admit of a repeated separation of chyle, which is
also confirmed by the dry, thick, excrementitious contents of the short
colon. Ramdohr supposes that the biliary vessels, from their in general
ascending and descending the duodenum, but subsequently spreading
themselves about the greatest convolutions of the ilium, imbibe from it
nutritive matter during the passage of the chyme, and that it is thence
that the latter contains less moisture in the ilium : he ascribes the same

De Glandul see. Str, par. pp. 68, 69.

378

PHYSIOLOGY.

function likewise to the great gut, and, as the clavate gut is the same
organ, it would necessarily also be attributable to this. Thus much is
certain, that the chyme is further elaborated and extracted in the great
gut of such larvae before it is rejected from the body by the colon.

A function limited to the conveyance of the chyme cannot be
attributed to the very long ilium of the carnivorous insects, namely,
the j Dytici and Peltodea, particularly as it is not only longer here than
the duodenum, but even several times its length, for example in Necro -
pfiorus. In these, evidently, as in the higher animals, the ilium
must throughout its whole course separate chyle ; at least, a thin
finely divided chyme is found throughout it. I am of the same
opinion of the likewise very long ilium of the Lepidoptera, for the
small egg-shaped stomach is too insignificant to separate all the chyle
requisite for their support, although, as experience teaches us, the
Lepidoptera are very temperate in the taking of food, and exhibit no
trace of their previously voracious appetite as larvae. All these insects
with a long ilium have no distinct thick intestine, whereas in those with
a short ilium, for example, the Capricorns and Lamellicornia, we find
it described by Ramdohr as the clavate intestine. In the cockchafer
and the other Lamellicornia, in their perfect state, instead of the broad
sack-shaped thick intestine, we find an oval longitudinal thick gut,
which is internally furnished with projecting longitudinal folds, which,
as well as in the larvae, subjects the chyme to a second elaboration, and
also extracts it, for which purpose it appears to require the longitudinal
folds. This second extraction can also, if it, which we may not doubt,
likewise takes place in those insects which have a long ilium, occur only
in the ilium. Indeed, such insects, namely, the Dytici , Peltodea, and
lepidoptera, have a longer or shorter caecum, which, in Dyticus, is
nearly half the length of the intestinal canal, and wherein the chyme
may possibly be subjected to a second digestion. In favour of this opinion
the multitude of glands upon its inner surface speak, as well as the
viscous nature of all the nutriment contained within it. But we do not
always find it filled with chyme, occasionally only in Dyticus ; it some-
times only contains air, whence is explained Leon Dufour’s opinion of its
supplying the place of a swimming bladder. In the Lepidoptera, the
brownish red fluid accumulates in it during the pupa state, which
is rejected upon the exclusion of the perfect insect, and which,
according to chemical analysis, consists chiefly of uric acid, and very
much corresponds with the excretion of the biliary vessels. Treviranus,

OF DIGESTION.

379

therefore, compares this caecum of the Lepidoptera to the urinary
bladder, and it would we were to institute an analogy with the birds,
be analogous to the bursa Fabricii of those animals. Thus much is
certain, that this caecum cannot be of so much importance to digestion
as, for example, the caecum of the Rodentia, or the clavate and thick
intestine of other insects which are analogous organs.

The true rejecting portion of the intestinal canal is therefore the
colon. By its considerable size, in the majority of cases, it is adapted
to the reception of much matter, and peculiarly adapted, by its strong
muscular structure, to the compression of it into lumps of excrement.
To promote this object, it has in many cases hard horny ridges and
prominences, which assist it in its function. The shape of the ex-
crement depends both upon the size of the colon and its folds. It is so
various in the caterpillars of the Lepidoptera, that frequently, with a
little attention, distinct genera and species may be distinguished by it,
a skill which is not unimportant to those who have the care of planta-
tions. In general, vegetable-feeding insects produce more excrement
than the carnivorous ones. This is distinctly shown in the caterpillars
and grasshoppers, the short but broad colon of which exclude at
intervals of a few minutes considerable balls of excrement, which are
shaped precisely according to its form. In general, the digestion of
these insects is so rapid, that the just filled intestinal canal will have
extracted all the chyle in the course of one hour, and the caterpillar
recommence eating. Indeed, the food passes through the entire intes-
tine merely to make room for constantly succeeding food, and a voracious
caterpillar, therefore, will be continually evacuating excrement. In
the perfect insect, the colon is wider than the rest of the intestine,
but towards the anus it again contracts, and it consequently evacuates
the excrement in smaller, at least thinner, portions, or in a more fluid,
thick, pappy consistency ; haustellate insects, such as the Lepidoptera
and flies, reject it quite liquid. The colour of the excrement also
depends upon the difference of food ; for instance, that of the cockchafer
is green, like the leaf of the plant upon which it feeds ; that of the
water beetle of a yellow white, like the flesh he has eaten ; that of the
flea red, like the blood it has imbibed ; yet the colour always changes
a little ; it becomes, namely, darker, brownish or blackish, as in the
flies, which lap so many different kinds of nutriment. No peculiar
offensive or stinking smell is observed in the excrement of insects, and,
indeed, their rapid digestion does not admit of so complete a decom-

380

PHYSIOLOGY.

position as in the higher animals, particularly as the entire digestion of
insects is almost limited to the imbibition of the juices contained in
their food.

§ 225.

Lastly, we must here treat of some peculiar secretions which are the
produce of digestion, or at least in their fundamental parts, but which
exercise no influence upon it : among these we consider the secretion of
the spinning vessels and other secerning organs, namely, those of the
poison glands.

The spinning vessels (§ 112), which are found only in larvae, are
long twisted canals, which empty themselves into the spinning vessel
found in the under lip, or in some rare instances, for example, in the
larva of Myrmecoleon, present themselves in the shape of a pyriform
bag, which, in the perfect insect, appears to be transformed into the
colon : they lie at the anal extremity, and contain a viscous fluid, which,
in the younger larvae, is quite transparent, but, in more mature ones,
it is more opaque and thicker. From this fluid the larva spins delicate
filaments, which speedily harden in the air, and are then no longer
soluble in water. The entire spinning vessel also, when dried in the
air, likewise hardens to a firm fragile mass. Chemical analysis discovers
the components of this fluid to consist of a substance like lime, a waxy
portion, and a little coloured oil which smells like anise. Acids poured
upon it harden it ; in young caterpillars it precipitates a flocky sub-
stance (albumen) ; but in very concentrated acid it dissolves, as well as
in a solution of pure potass : from the former it was precipitated by the
addition of water, and from the latter by that of acid in a flocky shape.
Hence it appears, that, besides animal albumen, a resinous and an oily
substance form components of the spinning fluid, in favour of which
the adhesiveness of the fresh material, its rapid drying, and fragility in
a mass, speak greatly. It is, consequently, purely an excretion, and is
made for the purpose of removing from the body the oily and resinous
vegetable portions which are received into the blood by digestion, and
again separated from it by the spinning vessels. In the spiders, which
feed upon animal substances, and, therefore, doubtlessly, in the larvae
of the Phryganece and in the Antiion , &c., which also devour animal
matter, it also contains ammonia * and a material allied to the horny

Gmclin’s Chemie, vol. ii. Pt. 2, p. 1475.

OF DIGESTION.

381

substance, the presence of which is to be deduced from the variety of
tlieir food.

True poison glands are less generally distributed : we have de-
scribed them above (§ 140) among the appendages of the female
sexual organs. They are found only in the Hymenoptera, viz. in the
Pompili, Spheges, wasps and bees. The secretion of these organs is a
sharp corrosive fluid, which is the principal cause of the violent pain
that is experienced from the puncture of these insects. The form of
the sting, which has also been described above (§ 145), enables them
to insert this poison into the wound at the time of the puncture, as the
sting is not simple, but consists of several setse, which form a narrow
canal. We find, likewise, in the Lepidoptera , appendages which, in
structure and place of opening, appear to be analogous to these poison
glands. This analogy is supported by the intelligence of some residents
at the Cape of Good Hope, who inform us that there is a lepidopterous
insect known there by the name of the bee-moth, which defends itself
in stinging when captured, and the puncture is so painful, that a large
swelling speedily arises which quickly produces inflammation *. The
chemical composition of this poisonous fluid cannot be given without
analysis : it perhaps contains a free acid allied to the formic acid, or is,
probably, the very same thing, which supposition is supported by the
similarity of the pain to that of a wound from an ant. These creatures,
namely, have no sting, but yet they possess the poison organs, and
project from their anus by raising their abdomen this sharp fluid against
their enemies. Its acuteness is shown by the violent pain caused
by being sprinkled with it. They also defend themselves by biting,
but their bite is harmless. That these organs are analogous forms
to the urinary organs of the Carabodea and Dytici, is on the one side
supported by their similar situation at the extremity of the body, yet
with this important difference, that these open above the intestinal

* Isis. 1831, p. 1917. From a letter received by Professor Reich from the Cape of
Good Hope. It is the opinion of the entomologists cited there, that the projecting sting
is the male organ, but it is contradicted by a Brazilian Cossus in the Royal Entomological
Collection at Berlin, and which is a female : it has a long and very pointed sting, which
is recurved, but I was not at liberty to inspect it more closely. According to analogy,
this sting can be nothing else than an ovipositor formed by the projection of the horny
ridges found in the vagina of all insects. It appears most to correspond with the sting of
the Hymenoptera , yet it appeared to me that the exterior sheaths were wanting, if I may
trust a very superficial glimpse which was all I could have of it.

382

PHYSIOLOGY.

canal, the former, however, beneath it, into the evacuating duct of the
sexual organs ; on the other side, by their similar form, they also
forming serpentine or ramose canals, which terminate in a larger
reservoir, or bladder. In both cases they are double, but the poison
organs empty themselves into a bladder with a single duct, whereas the
urinary bladders remain separated and have two distinct orifices.

We also discover frequently in insects peculiar secretions, which are
found limited to certain families. They betray themselves especially
by the smell which insects possessing them either constantly produce,
or only upon certain occasions. Thus the large Carabodea smell like
fresh Russia leather, which must be ascribed to a secretion that is
emitted through one of the articulating membranes. This supposition
is supported by the milky secretion which is poured forth in abundance
through the articulating membrane between the head and prothorax
and mesothorax, by recently captured Dytici, and which has an
offensive stench like that of putrid urine. In Meloe, a different
oily fluid is secreted in the articulating membranes of the legs. In
neither of the two former instances could I discover a distinct secreting
organ, and Brandt was equally unsuccessful in Meloe *. The sharp
secretion of the Cantharides is universally known, for which also no
distinct secreting organ is to be found, but which seems to be deposited
principally in the hard horny parts. Here the excretion exhibits
itself as a peculiar substance, wdiich chemists designate by the name
of cantharis camphort, and which alone possesses the property of
blistering. It is also found in other genera and species of this family,
for instance, in Mylabris, which is the true Cantharis of the ancients.
Other volatile, ethereal, and peculiar secretions are observed in
Callichroma moschatum, the spurious Spanish fly, which insect betrays
itself at a considerable distance even, by its agreeable and peculiar
smell ; in the stinking burying beetle ( Necrophorus ), dung beetles
( Scarabeus ), and in some Chrysomelae and Coccinellce. The last
especially, upon being touched, emit a yellow fluid through the segments
of the abdomen, which smells strongly of opium. Perhaps it is from
this that they have been applied in the toothach. The Hemiptera
are distinguished among the other orders, and especially the bugs, by a
very peculiar insufferable stench, which is, however, only to be detected

* Arzneithiere, vol. ii. Pt. 4, p. 104.

t Gmelin’s Chemie, vol. ii. Pt. 1, p. 427

OF DIGESTION.

383

upon touching or pressing the creature, and is probably produced by
a peculiar secretion, which serves them as a defence against their
enemies.

Among the Hymenoptera also many bees are distinguished by a
peculiar very agreeable smell, which may in many instances however
originate from the flowers they visit.

One genus of this large family, the domestic bee, produces a secre-
tion of a distinct nature, which is not found in any other insect. This
secretion, which distinguishes itself less by its smell than by its peculiar
quality, is the wax of which the bees construct their cells. The
secreting organ is found in the space between the ventral plates of the
five intermediate abdominal segments, and exhibits itself as a delicate,
soft, structureless membrane which passes from the superior half of
each ventral segment, and, describing an arch, inserts itself in the
preceding; hence it is the true articulating membrane itself, which
has here transformed itself into a perfect secreting organ. But such
a function of the articulating membrane is not without analogy in other
insects, for in the Dytici the membrane between the head and thorax,
in Meloe that between the femur and tibia, and in Coccinella that
between the several ventral plates, is a true secretory organ. The
form of the secreting surface presents itself as a long octagon, which is
divided into two halves by a central horny ridge. This octagon lies at
the anterior surface of each of the central five ventral plates, and stands
in connexion with the posterior side of the preceding plate, by means
of a process. Thus each bee has five secreting pockets in its abdomen.
In these pockets the wax is prepared in the form of very thin, white,
and very fragile plates, which are firmly attached to the secreting
surface, and thence removed when the bee wishes to construct a cell.
For this purpose it breaks the wax plates into small pieces, and by
means of its saliva it prepares with it a soft pappy substance, which
is stuck together in small pieces, and afterwards smoothed by the
mouth with the assistance of the saliva *. The saliva, therefore, from
possessing the property of dissolving the wax, must be of an alkaline
nature, which is proved also by its organs becoming red when laid in
vinegar. In the other families of the Hymenoptera , on the contrary,
namely, in the ants, a superfluity of acid is found in the body, which

* See G. R. Treviranus, in the Zeitscrift für Physiologie, vol. iii. p. 62., upon these
wax-prepaiing organs, and the mode in which the bees work it.

384

PHYSIOLOGY.

betrays itself not merely by its smell but more by a peculiar but not
unpleasant taste. That this acid is found especially in the abdomen is
well known, but we are unacquainted with the organ that secretes it ;
it is probable that the poison organs and the acid are both merely a very
sharp urine.

Among the Lepidoptera peculiar secreting organs have been found
in some larvae, for instance, in the larva of Harpya vinula, which has
a little bag at the ventral plate of the first abdominal segment, that,
when filled, is of about the size of a pea, and the aperture to which is
a transverse incision at the same spot. The fluid contained in it is a
powerful acid, which produces pain and inflammation upon a delicate
skin *. In the caterpillar of Pieris Machaon there is a similar furcate
secreting organ in the neck, which is projected upon its being roughly
handled. The getting greasy, as it is called in Lepidoptera , also indicates
a great provision of secreted juices. In Harpya vinula it is frequently
the case, and we might thence suppose it to be consequent upon
the secretions of the caterpillar. The liquid, however, seems to be
no oil, but rather an acid. Lastly, among the Diptera we find
individual instances of a presence of peculiar secretions, for example,
in Ccenomya Jerruginea, Meig. ( Sicus ferrug ., S. bilicor, and S.
errans , Fab.) ; some of the flies which belong to the division of those
with a spiny scutellum (Dipt, notacanlha'), which Meigen called whey
flies, from their penetrating smell, resembling that of green whey
cheese. This smell, which proceeds from the whole body, and which
cannot be ascribed to any local excretion, remains even a long time
after death, whereas the majority of such odours then speedily eva-
porate.

§ 226.

II. FUNCTION OF THE AIR TUBES, RESPIRATION.

The chief object of respiration is to adapt the circulating fluid
destined for assimilation with the organic mass to that purpose, by the
addition of another substance, viz., atmospheric air or oxygen. To
attain this we find in the majority of instances distinct respiratory
organs, namely, a more or less distributed respiratory surface, which
must be purely considered as either an internally or externally produced
continuation of the epidermis, and in which the fluid circulates, and

Rengger’s Physiolog. Untersuch., p. 427.

OF RESPIRATION.

385

which thus stands in constant connexion with the air, whereas, when
this continuation of the epidermis forms an internal cavity, the oxidised
respiratory medium is received in it. These cavities, which are every-
where distributed throughout the bodies of insects, we have described
above, according to their most general forms, as air tubes or tracheae ;
they constitute the respiratory organ, which is consequently neither
external nor partial, but is distributed throughout the entire compass
of the cavity of the body in uniform perfection. The structure of the
respiratory organ will, therefore, be fully known when we shall have
proved that these air tubes and no other portion of the body actually
constitute it. Commencing with this proof, the subsequent divisions of
this chapter will be occupied with the mechanism of respiration, and
its effects upon the corporeal functions.

§ 227.

With respect to the proofs that the tracheae are the actual respi-
ratory organs of insects, the most superficial anatomical inspection of an
insect shows us that air is found in these tubes, and that we nowhere
find internal apertures to these tracheae, but constantly external ones.
Besides, air is seen to pass through the external orifices, or spiracles,
when living insects are cast into water, as air bladders rise from them
to the surface of the water. But Treviranus’s * experiment is the
strongest proof ; he placed the large green locust ( Locusta viridissima )
beneath a turned up glass filled with water, and then saw an air bubble
rise from the spiracle between the meso- and meta-thorax, which regu-
larly decreased with the respiratory motion of the creature, and again
increased with its distension. Hausmann also observed an ascent and
descent of the water in a glass tube closed above, the superior space of
which contained air and a green locust, and this took place syn-
chronally with the inspiration and expiration of the insect f. Other
facts which prove the function of the air tubes as respiratory organs
are, for instance, the speedy death of all insects whose spiracles are
closed with oil or gum, so that no fresh air can enter the tracheae,
besides the ascending to the surface of all such water insects which
have no branchiae, and lastly, the projection to the surface of the air-
tubes whilst the remainder of the creature is immersed in the water.
In addition to these direct observations upon the respiratory function of

* Biologie, vol. iv. p. 158. t De Animal, exsang. respirat., p. 8.

C C

386

PHYSIOLOGY.

tracheae we have other indirect proofs derived from their structure.
These are their anatomical conformity with the tracheae of the higher
animals, their distension into bags and bladders, which correspond with
the cells of the lungs and its bags ; and, lastly, the deficiency of a
peculiar respiratory organ, which would be the more necessary in insects,
from their being covered with a hard integument, which could not
exercise that function. All these facts confirm the tracheae to be the
true and sole respiratory organs of insects, and that air containing oxy-
gen is received into them through the spiracles, air tubes, or branchiae.

§ 228.

If we now return to the mechanism of respiration, we shall find that
it presents itself throughout the animal world as a rhythmical motion
of the body, whereby the medium containing the oxygen is brought into
incessant contact with the respiratory organs. This motion in insects
is consequently for the purpose of introducing atmospheric air within
the tracheae, which object is attained by the opening of the spiracles
which close the apertures of the tracheae. If the abdomen of the insect
distends at the same time as the spiracles open, the air must necessarily
pass into the tubes which are now opened, and when the abdomen
contracts, the just inspired air will consequently be forced out again.
Thus all respiratory motion presents itself as a rhythmical compression
and expansion of the cavities of the body, and especially of the abdomen.
The muscles which produce this motion are the same as those described
above as connecting the several parts of the skeleton together, namely,
the straight dorsal and ventral muscles of the abdomen. The thorax
appears to participate less in the contraction of the cavities of the body,
at least no contraction or dilatation of it is to be detected in insects
quietly breathing; and also the intimate and firm connexion of the
several parts of it together prevents such an alteration of its compass
in repose. But whether the cavities of the tracheae are also contracted
upon the considerable compression of the abdomen, is uncertain.
Nitzsch * has in many instances observed that there was no alteration
during respiration, whereas he detected in the large air bladders of the
Diptera and of the Hymenoptera a distinct compression upon the con-
traction of the abdomen, but which evidently appeared to proceed from
the latter, and not from a contraction of the air bladder itself f . Hence,

* Comment, de Respirat. Animal, p. 38.

Ibid. p. 39.

OF RESPIRATION,

387

therefore, the rigid spiral filament which encircles all tracheae is
especially adapted to its constant distension, precisely as is the case
with the cartilaginous tracheae of the superior animals. Consequently,
by means of the elasticity of this filament, the trachea spontaneously
distends upon the distension of the abdomen, the compression of which
had decreased its compass ; and possibly it is as much distended beyond
its natural size, by the introduction of air upon inspiration, as it had
been previously contracted by the contraction of the abdomen, at least
Comparetti’s experiments * upon locusts opened alive appear to indicate
as much, but it cannot be kept constantly contracted or distended
beyond its usual size owing to this filament.

In general the respiratory motion is very unequal ; it is either
quicker or slower, according to the state of excitement or repose of the
entire system. It appears also to vary considerably in the several
orders. Sorg observed t in Lucanus Cervus from twenty to twenty-five
contractions in a minute, whereas in Locusla viridissima J there were
from fifty to fifty-five, and in Deilephila Euphorbia § only twenty.
In a cockchafer, whose elytra I had cut half off, I could detect no
pulsation at all, even with the greatest attention, and by means of a
lens, so long as it remained inactive and as it were asleep ; but upon
taking it into my hand, the warmth of which aroused it, pulsations
were to be seen, at first, it is true, very irregular, both in intensity and
the interval that elapsed between them, but it at last breathed regularly
when preparing for flight, and there were now about twenty-five
contractions in a minute ; but the abdomen after each contraction
gradually decreased, never subsequently distending so widely as at first,
but likewise it compressed itself more and more, so that there was an
equal ratio between the decrease of its dilatation and the increase of its
contraction. Shortly before taking flight it moved its whole body as it
were convulsively, the head was protruded and withdrawn, pro- and
mesothorax were also loosened from each other and again brought
together, and, lastly, the valve of the cloaca was widely opened, and it
appeared to struggle during its violent respiration as if desirous of
disencumbering itself of an oppressive load. But all its endeavours

* Obs. Anat. de Aura Interna comp. p. 290, according to Treviranus’s Biologie, vol.
iv. p. 161.

t Disquisit. Physiol, circa Respirat. Insectorum et Vermium, p. 27.

+ Ibid. p. 46. § Ibid. p. 66.

388

PHYSIOLOGY.

were in vain, for its clipped wings made flight impossible. IAbellulcei
which are held by the wings behind, may be very well examined, and
the pulsations of the abdomen are very distinct, but no motion is to be
detected in the thorax. The number of these pulsations is greater than
in the cockchafer, but not so great as in the green locust. I estimate
them at from thirty to thirty-five in a minute. I consider, besides,
that the pulsations increase when the voluntary motions, for instance,
that of flight, are in exercise, which I conclude from the respiration of
a Libellula held in the above manner, increasing upon its endeavours
to free itself. During this, however, the spiracles of the abdomen did
not appear to inspire, and the contractions of the abdomen recommenced
only after the motion of the thorax. Treviranus* concluded, from
similar observations, and, indeed, justly, that the spiracles of the
abdomen respire during repose, whereas those of the thorax are especially
in action during flight. He cites as a proof, that the same muscles
which contract the cavity of the thorax, our straight dorsal and pectoral
muscles as well as the oblique lateral and dorso-lateral muscles, effect
the first expansion of the wings by the general contraction of the thorax,
and, subsequently, in conjunction with the true alary muscles, produce
the motion of flight by the alternating distension and contraction of
the thorax. During this motion of the thorax, air must necessarily
pour in and out, particularly as the expiration of the abdomen pro-
gressively increases, as is proved by my observations upon the cockchafer,
and the deeper it becomes, the earlier do the spiracles of the thorax
commence breathing, and this supposition is strongly supported by the
motion of the head and prothorax. At the very moment, however, that
the beetle flies off, it compresses its whole abdomen together, and this
is continued during its whole flight, a clear proof that the whole function
of respiration now is effected by the spiracles of the thorax. We may
also note that the sudden breathing of the abdomen in insects upon their
settling after flight, namely, in the flies, bees, and wasps, tends to
support it. The longer the creature reposes, the slower and more
regular the pulsations of the abdomen become. This opinion also of
the respiration through the spiracles of the thorax gives a sufficient,
explanation of the humming noises produced by most insects during
flight, as I shall prove in detail below, for it cannot be conceived that
the mere flapping of the wing can produce it, but that it proceeds

* Das organische Leben, t. i. p. 262.

OF RESPIRATION.

389

from the air streaming in and out of the thorax during flight. We
find also the motion in the wings of insects even at rest during their
chirping and crying, for instance, of the great grasshopper, to harmonise
with this opinion, for without the air streaming out of the thorax upon
the fluttering wings, not a tone could be produced. Therefore, the
voice of all insects is no mechanical friction of portions of the skeleton,
but in them, as elsewhere, it stands in immediate connexion with the
respiratory apparatus and its outlets.

§ 229.

The spiracles themselves participate somewhat in the pulsations of
the entire body, at least in the larger ones which lie exposed upon the
surface of the body on opening and shutting of them, synchronal with
the in- and ex-piration has been observed. We also know, from
the preceding description of all the forms of these spiracles, that only
those which lie exposed are supplied with a peculiar apparatus for
the opening and closing of their lips, whereas those which are
concealed beneath portions of the skeleton exhibit either none or
only a partially closing margin. Such spiracles consequently do not
appear to be able to be closed, but the air seems constantly to pass in
and out with each breath. Other writers, on the contrary, maintain a
complete closing of the spiracle in some insects by means of extraneous
substances which lay in front of it. Reaumur was the first to observe
this closing of the spiracles in a pupa by means of a viscous substance,
and Sprengel * confirmed it. If now such a substance shall have
been observed in insulated cases, which may not be doubted, from the
positive assertion of Sprengel, it can occur only as an exception, per-
haps, in consequence of the diseased state of the caterpillar ; or it was
perhaps a peculiar secretion which was separated around the spiracle,
and at a moment of danger, for instance, upon being touched, flowed
in front of the spiracle, to prevent the application of something preju-
dicial j subsequently, however, when the caterpillar no longer feared
the presence of its enemy, was again absorbed, or mechanically removed ;
perhaps also the substance may have got there by accident. In all
cases, however, free respiration would be impeded by it, and this
stoppage could not last long without becoming prejudicial to the insect.
It appears, therefore, probable to me, that all pupa in which such

Comment, de Partib. § 4.

390

PHYSIOLOGY.

a stoppage of the spiracles has been observed, were either dead or upon
the point of death. But that the function of respiration may be long
interrupted in pupa, is attested by a number of experiments, and,
therefore, it is not at all improbable that the pupa may have exhibited
signs of life even when its spiracles were stopped up.

The earliest physiologists, viz. Malpighi and Reaumur, instituted
experiments upon the effects of stopping the spiracles with oil or gum,
and obtained the result, that if the stoppage were long continued, it
would cause the death of the insect. More recently, Moldenhawer *,
in proof of his view that the spiracles were not the orifices of the
respiratory organs, made many experiments by stopping them with oil,
and the result obtained from his investigations was, that not merely
stopping the spiracles, but even merely brushing it over with oil, was fatal
to the insect system. But this is not the case. G. R. Treviranus f,
who repeated many of his experiments, observed death to ensue only
upon the stoppage of all its spiracles, and not when the body or portions
of it were brushed over with oil ; and indeed upon the complete stoppage
of all the spiracles, it was some hours before death was produced. This
was the case with insects found under water. But the effects of the
stoppage were very various : caterpillars lived longest ; perfect insects
were sooner killed ; some, even upon a partial coating of oil, for instance,
a wasp, the breast and venter of which was covered with oil of almonds,
died in a few minutes. But as it is precisely upon the breast and
ventral portions that the orifices of the spiracles are placed, we may pre-
sume that they were stopped in this experiment. That it does not prove
fatal to cover some only of the spiracles, is proved by an experiment
upon a Meloe , the ventral spiracles of which were closed. Its preceding
activity remained almost unaltered, for the spiracles of the breast, which
Treviranus does not indeed know in insects, remained free, and through
these the beetle could breathe

Whereas it has been observed upon the covering of some of the
spiracles only, namely, those lying upon the same segments, there
ensued a partial laming of that portion of the body thus deprived of

* Beiträge zur Anatomie der Pflanzen, p. 309.
f Biologie, vol. iv. p. 151.

+ Das organische Leben, p. 257. The majority of observations here made upon the
situation of the spiracles in the several orders is erroneous, as the description we have given
above will prove.

OF RESPIRATION.

391

air, Reaumur and Bonnet * among the earlier naturalists, and
Treviranus among the moderns, have made experiments upon this
point. According to Bonnet, the oil inserts itself within the spiracle,
and by that means still more impedes respiration. Treviranus, who
stopped only the posterior spiracles of the caterpillar of Cossus ligniperda
with oil,* observed a trembling, and raising of the last abdominal
segment, but which, however, soon disappeared, after which the cater-
pillar exhibited no further morbid symptom. The same was the case
with a green locust, the thoracic spiracles of which were stopped with
oil : at first the legs appeared to become weaker and motionless, but it
subsequently recovered. My opinion is that this phenomenon of a
partial laming can present itself only immediately after the closing of
the spiracle, for subsequently air will pass from other spiracles into
those tracheae whose orifices have been closed, particularly as all the
tracheae stand in immediate connexion together, at least in the majority
of insects. It is only so long as the organisation is deprived of this
auxiliary assistance, that symptoms of lameness can appear. But even
without this assistance, it is scarcely advisable to seek in animals which
stand only upon a central grade of organisation for the uniform pheno-
mena observable in the more regulated conditions of life of the superior
animals. How long a time cannot insects pass beneath water or in
spirits of wine without respiring, and yet recover from their stupor !
In the latter they indeed speedily die, but I know many instances of
beetles having been immersed in spirits of wine for twelve hours, and,
upon being removed from it, recover all their functions. But it is
much more fatal for insects to inspire air impregnated with the fumes
of evaporated spirits of wine ; it is true that here they die more slowly,
but at the latest in the course of half an hour, and when once thoroughly
made torpid, they do not again recover.

§ 230.

The mechanism of respiration in insects which live in water is not
in general different from that of those which live constantly in the air.
But this observation refers especially to those only which breathe even
in this medium through spiracles, whereas the process in those which
breathe through gills is somewhat different.

Those water insects which breathe through spiracles must come to

Contemplations de la Nature, t. ii.

392

PHYSIOLOGY.

the surface of the water when they wish for fresh air, and bring that
portion of their body provided with these apertures in communication
with the air above the surface. Among the beetles there are two
families especially which live in the water, namely, the Hydrocantharides
and Hydrophilus. The mechanism of respiration differs in both. The
Dytici, when they wish to breathe, bring the posterior extremity of
their body to the surface of the water, and they then separate the last
segment of the abdomen from the elytra, and thus admit air beneath
the elytra within the space between them and the abdomen ; they then
close it by pressing the last segment firmly to the abdomen, and
return with their fresh supply to the bottom of the water. Here
this air is so long inspired by the spiracles, which are situated also
within this cavity between the elytra and the abdomen, as it is fit
for respiration, after which the insect returns to the surface of the
water, again to renew its supply. We thus observe in these insects
the same process as we find in those which live in the air. The
Hydrophili breathe differently. These, as Nitzsch * has observed and
described in detail, do not bring the apex of the abdomen, but the head,
to the surface of the water, and then project one of their clavate
antennae, the whole clava of which is covered with fine hair, until it
comes into contact with the air. But they so twist the clava that its
base is exposed to the air and the apex touches the breast, which, as
well as the whole underside of the insect, is clothed with short silky
pubescence. By this means a communication is made with the external
air and that beneath the water covering both the clava of the antennae
and the whole under surface of the insect to which it adheres by means
of the coating of down, and by means of this communication fresh air
is transmitted to the venter of the insect, and by the same means the
expired air is also removed, and the air is likewise transmitted from
the ventral surface beneath the elytra, where it is in- and expired by
the spiracles there situated. It is to the air thus adhering to the venter
that the Hydrophili are indebted for their lightness. It is with diffi-
culty that the majority can keep themselves at the bottom of the water
by clinging to substances there, and, when once at the surface, only by
the help of other bodies, for example, the stem of a plant, down which
they creep, can they recover their situation beneath. The great
Hydrophilus piceus alone, by means of its stronger muscular power,

Reil’s Archiv, für Physiologic, t. x. p. 440.

OP RESPIRATION.

393

can work itself beneath the water, and swim about in it, although but
slowly, if unassisted, whereas the Dytici swim with the greatest facility
on all sides. — A third type of water beetles, the Gyrinus or whirlwig,
also conveys an air bladder with it when it dives, which he can accom-
plish only with difficulty and the greatest exertion, or by means of
other assistance ; he, however, receives the air posteriorly between the
abdomen and the elytra, which is the easier to him as he swims freely
about in circles upon the surface. The larvae of the Dytici and
Hydrophili likewise breathe through spiracles which are situated at
the anal extremity ; they therefore only require to bring the end of the
tail to the surface of the water when they wish to respire. They are,
therefore, seen with a raised tail and pendent head hanging to the
surface by means of their plumose anal leaves. As soon as an enemy
approaches they hastily seek the bottom, but in the course of a few
seconds resume their former position. The perfect insect, however,
can remain longer beneath the water, as it conveys a supply of un-
decomposed atmospheric air with it.

The majority of the remaining insects which dwell in water breathe
through tubes, with the exception of those which breathe by means of
gills. The mechanism of this mode of respiration scarcely differs from
that of the general mechanism of respiration. By raising the air tube
to the surface of the water, the influx of fresh air is admitted to the
trachea^ and this ensues upon each expansion of the cavities of the body,
whereas by means of each contraction the previously inspired air is
again rejected. But it appears probable to me that expiration is
effected not solely by the posterior tubes, but also through an aperture
immediately behind the head in the first segment of the body. I have
indicated these apertures in the description given above of the respiratory
apparatus of the rat-tailed maggot j they are also found in the majority
of the larvae of the Diplera which do not live in water, for instance, in
the maggots of the Muscce , and also probably in the larvae of the gnats,
and in these they then develope themselves to the subsequent air tube
in the thorax of the pupa. As now these anterior apertures remain
constantly in the water, they cannot serve for inspiration, but being
present they cannot be superfluous in the organisation of the larva ;
besides, nothing appears more probable than that the inspired air is
again expired through these anterior apertures.

394

PHYSIOLOGY.

§ 231.

Respiration by means of gills is found only in such insects as live
wholly in the water. The situation, form, and differences of these
organs have been given above ( § 126 ) in sufficient detail : we will
merely add here somewhat upon the mechanism of this mode of
respiration. By their deficiency of external apertures the gills are
chiefly distinguished from the other organs of respiration. The reception
of atmospheric air within the tracheae is thereby naturally rendered
more difficult, for its imbibition through the tunic of the gills must
proceed more slowly than its mechanical reception through numerous
apertures. The gills, consequently, form large broad leaves or long
bunches of hair, around which circulates the medium containing the
oxygen. A second condition of the reception of this gas by means of
gills is the constant motion of these organs, by means of which motion,
fresh particles of water, saturated with this gas, are brought into
contact with the gills. This motion of the branchiae varies accord-
ing to their situation and form.

Lamellate gills, situated at the sides of the abdomen, move like the
fins of fishes from front backwards, so that throughout the whole series
of these branchial leaves a constant undulating motion is perceived.
The first lamellae bend forwards, whilst the posterior ones strike back-
wards, and while the former strike backwards, the latter are bending
forwards. Thus the motion of all the gills is not contemporaneous,
but both progressive and alternating. By this means these larvae do
not swim in thrusts, but regularly, as by means of a portion of the
leaves of their gills they are constantly propelled the while another
portion reposes, and by this portion they are kept in motion when the
preceding is again inactive. By this continued motion of the branchiae,
the larva is constantly changing place, and thereby an incessant influx
of fresh air is promoted.

But if the lamellate or hair-shaped gills are placed at the anal
extremity of the body, motion is produced by the serpentining of the
abdomen, just in the same way as worms without swimming leaves move
in water. Thus the larvae of the Agrions swim and breathe at the
same time. And, lastly, if the gills lie in the colon itself, as in the
larvae of AEschna and Libellula, by the opening of the anus and the
distension of the colon, water is received in the cavity of this organ.

OF RESPIRATION.

395

and by its compression again rejected : and by the rejection of the
water it is that these larvae move.

Hair-shaped gills, which are situated upon the thorax, appear but
rarely to move independently ; in the majority of cases it is by means
of the motion of the entire animal, which is effected by the serpentining
abdomen, that these gills come in contact with fresh water. It is in
this manner that the pupa of Chironomus swims, and its whole motion
is consequently a respiratory motion, for these pupa take no nutri-
ment. A variation from this is the serpentine motion of the anterior
portion of the body when the animal has attached itself by its tail.
This motion also, which Nitzsch * observed in the pupa of Chironomus
plumosus, is a mere respiratory motion. Lastly, if the pupa dwells in
an open case, the entire bunch of gills moves either within it or on
its exterior : thus the pupa of Simulia appears to breathe. Whereas
the contact of fresh water with the bunch of gills, which in the larvae
of Phryganea are situated within the case, is effected by the motion of
the entire insect, in which fresh water is received anteriorly within the
cylindrical cavity, and, when expired, is again rejected by the posterior
aperture.

§ 232.

The question now arises, how do the insects breathe which dwell
within the internal cavities of other animals whither little or no
atmospheric air can reach ?

To answer this question, we must first illustrate the cases in which
insects are found in the interior of other animals. All these cases
refer to two chief differences, for either these insects live in cavities to
which atmospheric air can easily and does actually reach, and in which
case their respiration has nothing problematical and wonderful ; or else
they live in cavities which are thoroughly closed from the admission of
any air. The first case is found in the instance of the larvae of the
( Estri . These dwell either in the cavities of the nose or stomach, or
beneath the skin, in tumours in horses and the ruminantia. The air
can reach all these cavities, which also contain atmospheric air, and
indeed those larvae which live in tumours constantly protrude their anal
end, where the two spiracles are placed, out of the tumour, and thus

Comment, de respirat. Animalium, p. 40.

396

PHYSIOLOGY.

breathe like all others, or rather like the majority of the larvae of the
Diptera. The second instance, however, is found in the Ichneumons,
which do not live in the intestine, but in the cavity of the body of other
insects, between the intestine and the skin. That these creatures must
breathe admits of no doubt ; and indeed that they breathe precisely in
the same way as the larvae of the other Hymenoptera, namely, through
spiracles, is as certain as that they do not at all differ in their organi-
sation from those larvae. We can, therefore, adopt no other supposition
than that such larvae participate in the respiration of the insect upon
which they are parasitic, and that they breathe the air that passes
through the tracheae into the cavity of the body, or that they pierce a
trachea, and, remaining in its vicinity, respire the air pouring from it.
Such a wound to the respiratory apparatus would not produce death,
for it has still sufficient unwounded tracheae, and it would require only
to be a small branch that would admit of the passage of sufficient air for
the minute larva of an Ichneumon. Those caterpillars infested by-
parasites are always evidently ill, and this disease may proceed perhaps
from the interruption in various parts of the function of respiration,
and this interruption, together with the constant decrease of the fatty
substance of the pupa, may deprive it of its remaining strength, and
thus slowly kill it. After the death of the pupa, the remainder of its
internal organs are consumed by the parasite, or else the numerous
parasitic larvse pierce the skin of the caterpillar, and thus kill it before
it can change into the pupa state.

§ 233.

Having now shown the various kinds of mechanism by which
atmospheric air is admitted to the internal organs of respiration, we
further ask what is the object of this admission of atmospheric air, and
what changes does it itself undergo ? The reply is given in the result
of the various experiments of Sorg, Hausmann, and others, upon the
decomposition of air during the breathing of insects, and it is, “ All
breathing insects deprive the air of a considerable portion of its oxygen,
and give off in lieu of it carbonic acid/* The quantity of oxygen
withdrawn by breathing varies according to the size of the creature,
and the intensity of its respiration, and the quantity of carbonic acid
given off varies just as much. But thus much appears confirmed, that
considerably more oxygen is consumed by the creature than carbonic

OF RESPIRATION.

397

acid given off. And the more perfectly developed respiring animals
are, the less are they enabled to deprive atmospheric air of its whole
contents of oxygen : before its complete consumption they appear
languid, and, as it were, apoplectic, and they die upon the con-
tinuance of this state, or if they have not a fresh supply of air.
Whereas many insects, particularly butterflies, as animals upon a
lower grade of organisation, so entirely consume the oxygen in the air,
that in many experiments that have been made, not the hundredth
portion of that gas has been found left in it*. But the loss which
the air suffers by the withdrawal of the larger quantity of oxygen, in
lieu of which but one half the quantity of carbonic acid is given back
to it, appears to be replaced by a second excretion, consisting of azote.
One portion of this azote is given off by the lungs or air tubes, and
another portion, especially, by the perspiration of the skin. But as this
perspiration can be but trifling through the hard integument of insects,
if it be not indeed wholly deficient, they consequently must produce
less azote but a proportionably greater quantity of carbonic acid.

These are the chief results of the experiments upon the respiration
of insects. In proof of them we will give a tabular view of other
experiments of Treviranus, without adding more recent ones of our
own, occasioned by our less familiarity with such experiments, and
from our deficiency in the necessary auxiliaries and instruments.
And indeed the results of the experiments of so experienced and
competent an observer may well suffice.

* Sorg, pp. 65, 67.

398

PHYSIOLOGY.

Proportions of Absorption in the same time (100 minutes) and
quantity (100 grains').

Name of the Insect.

State of the
Thermom.
above °.

Quantity of
Respired
Air.

Excreted

Carbonic

Acid.

Absorbed

Oxygen.

Excreted

Azote.

Apis mellifica, neuter

11,5

27,2

0,82,

1,33

0,53

Another with violent mo-

48,6

2,25

2,77

0,52

tion and in the sun

Bombus lapidarius A.

12,5

3,8

0,31

0,43

0,12

B. -

23,7

1,70

C. -

10,0

0,72

terrestris in the sun

14—23

11,0

1,74

muscorum - -

46,2

0,64

0,82

0,18

Eristalisnemorum ( Meig .)
Pontia Brassicse ^Cater-

16—16,5

7,4

0,50

0,80

0,30

pillar)

14—13

2,8

0,16

0,28

0,12

Rapse A. after

starving 28 hours

8,3

0,72

2,26

1,54

B. on dying

13,5—17

2,0

0,20

0,37

Vanessa Atalanta A. after

3 days starving - -

13—28

27,0

2,65 (?)

2,85

B. the same

and weakened by the
preceding experiment -

105,0

1,50

2,35

Libellula depressa A.

17—16,5

6,2

0,37

0,74

0,37

16?5 i4

7,5

6,1

0,33

0,04

0,93

0,06

0,60

0,02

Cetonia aurata (larva)

A. - -

16,5

2,9

0,21

B. after 2

days starving

13,5—14,5

1,5

0,06

0,07

Melolontha horticola

13—15

2,0

0,07

0,17

0,10

Feronia nigra

11—15

4,8

0,23

0,56

0,33

If we still draw further results from the above experiments, we shall
find in these also a confirmation of the law deduced from the respiratory-
pulsations, namely, that in the sun and upon the general excitement of
the body the respiration is more violent and intensive than in repose or
in the shade. A working bee in the former situation inspired almost
double the quantity of air, consumed once as much more oxygen, and
gave off three times the quantity of carbonic acid, whereas the quantity
of rejected azote remained the same. The same result was produced
by several experiments made by Sorg* Hunger and the perfect satiation

OF RESPIRATION.

399

of the appetite likewise exercise great influence upon the function of
respiration, and indeed hunger, as in general, acts also enervatingly upon
respiration. Hungry insects breathe more slowly, but also longer, than
well-fed ones inclosed in the same quantity of air. The latter, how-
ever, produce, proportionately, considerably more carbonic acid. A
Cetonia, which was starved for three days, inspired less by half as
much air and rejected only one quarter as much carbonic acid as a
well-fed, healthy individual of the same species. The results are
similar in butterflies experimented upon under the same circumstances.

That the developing egg respires precisely in the same manner,
and under the same conditions, as the subsequent perfect insect, has
been proved above by experiments in our description of the develop-
ment of eggs.

§ 234.

Upon a careful investigation of respiration by means of gills, the
same results are produced ; the gills also imbibe oxygen, and give off
carbonic acid. But the question suggests itself whether in insects
which breathe by gills, these gills, as in the other animals writh
universally distributed blood-vessels, imbibe merely oxygen and expire
carbonic acid, or whether they inspire perfect atmospheric air and
expire the remainder, containing carbonic acid and azote, having sepa-
rated the oxygen from it. We must first inquire, whence do the gills
derive their oxygen ?-— Do they decompose the water, consisting of
oxygen and hydrogen ? — Or do they merely decompose the atmospheric
air contained within the water ? All experiments convince us that
the air only which is contained in the water is changed, and not the
water itself. Therefore, all animals die in distilled water deprived of
air, and, what is still more, insects die even in well water, which
contains more carbonic acid and in which less air is intermixed than in
the water of rivers or ponds. This prejudicial effect of well water
extends even to those insects which breathe through air tubes and
spiracles, and which for this purpose ascend to the surface of the water :
these also die quicker or slower in well water. But this does not
answer the question whether insects imbibe oxygen or air through the
gills. I think I must conclude that they extract the latter, from the
following considerations.

In the first place, because the larvae which breathe through gills
exhibit the same internal apparatus as those which breathe through
spiracles, and indeed generally possess larger internal air tubes than

400

PHYSIOLOGY.

the rest. Did the gills merely imbibe oxygen, smaller narrower vessels
would suffice.

Secondly, if pure oxygen were found in the tracheae of insects that
breathe through gills, they would be able to live a longer space of time
even in such media as contain no oxygen, for instance, until the
oxygen contained within their tracheae was consumed. But this is
not the case. Those larvae which breathe through gills are deprived of
life as quickly in spirits of wine as those which respire in the ordinary
way.

Thirdly, did insects with gills inspire pure oxygen, so would all
other insects, as the structure of their respiratory organs is the same,
be enabled without inconvenience to breathe pure oxygen. But this
is also not the case. Insects in pure oxygen breathe at first more
violently than irregularly, and die in the course of a few hours, before
near all the oxygen is consumed *.

It hence appears necessary to adopt the conclusion, that even in
insects breathing through gills there is a direct transmission of
atmospheric air through the branchiae into the tracheae.

§ 235.

If we next ask the object of all respiration, and the effect it exercises
upon the preservation and promotion of life, we shall find it to consist
especially in the alteration of the blood. Observations upon the
difference of the venous and arterial blood of the higher animals proves
that oxygen intermixed with arterial blood colours it more brightly,
and thus promotes its easier assimilation, although not by the mere
colouring, yet by the other changes it produces in it, the testimony of
which is its brighter colour. A similar alteration will necessarily take
place in the juices circulating in the bodies of insects, but in proof of
which we are the less enabled to give a striking instance, from, in the
first place, the blood of these animals being wholly colourless, and, from
the universal distribution of their respiratory organs, whence, conse-
quently, this alteration of the blood is constantly everywhere taking
place. In insects, therefore, arterial blood can alone be found, and the
motion of the juices which has been detected in insects of different
orders can consist merely in its general distribution, and not (as in
animals with perfectly distinct arteries and veins) have likewise for

Compare the Observations of Sorg, as above, pp. 19, 44, 98.

OF RESPIRATION.

401

©bject a motion to and from the organs of respiration. This will be
fully proved in the following division of this chapter.

But from the arterial blood all, and especially the animal, organs,
derive that portion which is peculiarly theirs, and which is transformed
in them. Hence respiration is the first and chief cause of the florid
health as well as of the equal and uniform nourishment of all the organs
of the animal. The muscles and nerves particularly appear to derive
advantage from respiration, in consequence of the change thereby
occasioned in the blood. Thence is it also that in animals with pre-
ponderant and highly developed organs of respiration muscular and
nervous activity prevails. That this is the case in insects, at least
with respect to their muscular power, requires no further proof; many
experiments and observations, and, indeed, daily experience, convinces
us of it. With what a monstrous expense of muscular power do not
these little creatures labour ! We have merely to reflect upon their
rapid and continued flight, upon the migrations of locusts, upon the
solid and compact woods which others destroy with their minute
mandibles, upon the powerful pressure which they are enabled to make
by their voluntary muscular force, when, for instance, a beetle is
taken in the hand, and it endeavours to free itself from its restraint.
With respect to their nervous activity, I will refer only to the sub-
tlety and strength of their sense of smell, particularly as this more than
any of the other senses stands in close connexion with respiration.
But their hearing is also acute, and, above all, their sight. Where
is there found such an accumulation of the organs of sight ? Where
such a relative size in any other class of animals ? Where so much
caution in the observation of their enemies, and patience in the com-
pletion of a once commenced undertaking ? but which patience must be
attributed to the acute perception of their senses and their great mus-
cular strength.

Hence respiration is, as well as the reception and digestion of food,
a chief cause of the undisturbed progress of all the animal functions ;
both go hand in hand, and the one is useless without the assistance of
the other.

§ 236.

Another property which, if not produced by respiration alone, yet
stands in an intimate connexion with it, is the peculiar warmth found
in many animal bodies, especially in the mammalia and birds. Without
entering here upon the several explanations of the causes of this equal

D D

402

PHYSIOLOGY.

temperature in both orders, in illustration of which we refer to the
condensed and learned comparisons of G. R. Treviranus *, we will
at once proceed to relate the observations that have been made upon the
subject of this heat in some insects.

These insects are the bees and the ants. In the bees Swammerdam
was the flrst to observe a peculiar warmth of the hive in winter, during
a very low external temperature f. He supposed this warmth was partly
to keep a portion of the honey fluid and partly to assist the eggs in
hatching and to prevent the bees from freezing. Since Swammerdam
similar observations have been made by Maraldif, Reaumur, and Huber.
Reaumur observed a thermometer standing at — 6J° external tem-
perature rise in the hive to -f 22^° ; according to Huber the average
temperature of the hive in winter is 86° — »80 F. This warmth
increased upon his causing a general motion among the bees by dis-
turbing them, and so much so, that the small glass window in the hive
soon became hot, whereas, when the bees were quiet and undisturbed,
it felt almost cold ; and indeed the wax of the combs melted several
times and ran down. From this experiment especially it has been
wished to conclude that the warmth in the hive is produced by the
motion of the bees, particularly by their occasional general fluttering,
which Maraldi considered to be the sole cause of the high temperature
of the hive. According to Huber §, however, this occasionally repeated
fluttering of the bees is produced by them merely to create a current of
air, whereby fresh air is introduced, and that rendered noxious by
continued respiration removed. In summer also, and not merely in
winter, do they do this, and thereby even at that season produce an
equally moderate temperature in the hive, which does not exceed that
of the external air. The same has been observed in ant hills, in
which the thermometer upon an external temperature of -f 10° rose,
according to Juch ||, to + 17°. In the wasps and humble bees, also,
which likewise live in society, we may with great probability infer a
similar phenomenon.

If after such facts it is undeniable that insects under certain circum-
stances can produce a higher but equal temperature, nothing further

* Biologie, t. v. p. 64, &c. Das organische Leben, t. i. p. 413, &c.

*|* Biblia Naturse, p. 161.

X Mem. del’ Acad, des Sc. de Paris, 1714, Ed. d’ Amst., p. 420.

§ Nouvelles Observ. sur les Abeilles, t. ii. p. 338, &c.

II Ideen zu einer Zoochemie, vol. i. p. 92.

CIRCULATION OF THE BLOOD.

403

may be thence concluded than that this warmth is produced only in
their social assemblage. Mere mechanical motion is, however, not
sufficient, for this produces in summer a lower temperature; the
single insect, on the contrary, produces no warmth, but is exposed
to the varieties of the external temperature, and dies when this sinks
below zero. Hence it merely remains possible to suppose that warmth
is developed by respiration.

We have learnt from a preceding paragraph that respiration increases
upon motion, and especially on flight, and that consequently there must
be a greater quantity of oxygen absorbed by the body. But the
condensation which the oxygen necessarily undergoes upon intermix-
ture with the blood, as well as the whole process of combustion, must
evolve heat, and this heat upon expiration must pass from the body of
the insect to the surrounding medium. If, therefore, many breathing
insects are collected together in a small space, heat must be produced
even during their quiet slow respiration, which the thermometer evinces ;
but if the swarm be put in motion, and if the bees flutter with their
wings, they breathe, consequently, more strongly and more intensely,
and, therefore, a greater quantity of earth is necessarily evolved.
Hence even every individual breathing insect would develope some
heat, which, however, from its rapid assimilation with the external
temperature, is not perceived. But in small spaces, and where many
individuals are inclosed together, this evolution of heat would certainly
be detected in other insects *. But the reason why the temperature
of the hive in summer is even less, or, at least, equal, upon the same
motion, to that of the external atmosphere, is to be explained by the
current of air produced by the motion by means of which fresh air is
introduced and the warmed air removed, as well as that each draught,
even upon the introduction of warm air, produces coolness.

§ 237.

III. FUNCTION OF THE DORSAL VESSEL. CIRCULATION OF
THE BLOOD f.

The most general physiological importance of the circulation of the
juices has been stated in the introduction to this chapter, and indicated

m Compare Hausmann de Anim. Ex. Respirat., pp. 68, &c.

It is quite impossible that we should here repeat all the different opinions of earlier
anatomists and physiologists upon the function of the dorsal vessel : we hope it will suffice
to assure our readers that all the most important treatises upon this subject have been
resorted to, and their most useful facts inserted.

D D 2

404

PHYSIOLOGY.

as a connecting link between digestion and respiration. The juices
prepared by the intestinal canal require the addition of oxygen from
the air before they can be assimilated with the corporeal mass, and for
this purpose they pass through the vessels to the respiratory organ.
Hence it appears that insects, from the universal distribution of their
respiratory organ, require no conducting of the juices, and it was this
consideration which, prior to a motion of the blood being observed in
them, that was sought to explain their deficiency of blood-vessels, and the
consequent deficiency of a circulation was thus illustrated as imperative.
We nevertheless find in insects a regular motion of the juices, as was
first discovered by the observations of Carus *, and subsequently con-
firmed by Wagner +. From the experiments of both these naturalists,
the following general result of the mode of this motion of the juices
has been found.

§ 238.

The juices prepared by digestion pass through the tunics of the
intestine into the free cavity of the abdomen among all the organs
there situated. It here presents itself as a clear and somewhat greenish
fluid, in which oval or round globules swim, which are likewise
transparent, and from to of a line in diameter. This fluid is
received by the dorsal vessel, or rather by its posterior portion, which
we have described as the heart, and which consists of a series of con-
secutive chambers furnished with apertures and valves (§ 117); through
these apertures during its distension, and then by means of the con-
traction of the same organ, through which also the lateral apertures are
closed by means of the valves lying in front of them, it is transmitted
from one chamber to the other, and then from the last into the aorta
The number of the contractions and expansions of the heart within a
certain time varies according to the stage of development and the state
of the temperature. The several chambers also do not simultaneously
contract, but, commencing posteriorly, they proceed successively, so
that the last and first frequently expand together, whilst the central

* Entdeckung eines Einfachen vom Herzen aus beschleunigten Blutlaufes in den
Larven netzflüglicher Insekten. Leipz. 1827. 4tb.

f Isis, 1832, p. 320.

^ We must here remark, that this structure of the heart, ascertained to exist by the
observations of Straus, was received and taught by even the earlier physiologists. See
Bonnet’s Contemplation de la Nature, t. i.

CIRCULATION OF THE BLOOD.

405

ones are still contracted. Thence proceeds the apparent undulating
motion which is perceived in the heart through the integument of the
body. From the anterior free aperture of the aorta the blood is driven
by this motion into the lateral space of the body contiguous to the
aorta, and it thence passes into all the vacant spaces of this cavity into
the antennae., feet, and wings, and thence, being continually driven on,
it pursues its course at the sides of the body, until it has again reached
the ventral cavity, where it then becomes mixed with the fluid there
found, and which has been subsequently formed by the constant activity
of the intestine, and upon the next expansion of the individual cham-
bers it passes again upon its preceding course.

§ 239.

The motion of the heart itself was observed by the earliest
anatomists. Malpighi even observed the contraction of the dorsal
vessel progressing from behind forwards, and Swammerdamm as well
as later anatomists have confirmed this observation. But as all con-
sidered the dorsal vessel as completely closed, it could lead to no insight
into the circulating system of insects, and all the observations upon the
manner of this motion of the dorsal vessel arrived at no important result.
Herold * alone, who made the dorsal vessel especially the object of his
investigations, recognised more distinctly its undulating motion. This
undulating motion may be readily understood from the recently
explained structure of the heart. Thus all the chambers do not simul-
taneously contract, but always one after the other, so that during the
contraction the posterior one drives its contents into the one before it,
and during its expansion again receives blood from the cavity of the
body. As this alternating contraction and expansion passes from one
chamber to the other, the motion of the entire heart, like the peristaltic
motion of the intestinal canal, appears to progress in an undulating
line, although the motion is not in the entire heart, but only in an
individual chamber ; but the motion of these chambers passes so quickly
from one to the other, that the first and the last frequently expand at
the same time, whilst those lying between still contract. W ith respect
to the number of the contractions and expansions, differences have been
observed in them, which partly, as in respiration, proceeded from the
temperature, and were partly dependent upon the stage of development.

Physiologische Untersuchungen über das Rückengefäsz der Insekten. Marb. 1823, 8vo.

406

PHYSIOLOGY.

Accor j;rg to Herold, the dorsal vessel of a full-grown caterpillar, in a
temperature of from 16° — 20° Reaum., made from 30 to 40 pulsations
in a minute, but sank in a temperature of from 10° — 12° down to from
6 to 8 pulsations in the same time. In younger caterpillars, the pulsa-
tions of the dorsal vessel, under similar circumstances, were quicker,
namely, from 46 to 48 times in a minute, in a temperature of 18°,
whereas in greater heat and with a quicker motion, in conjunction with
great exertion, the rapidity of the pulsations still further increases, but
they then appear so irregular and numerous, that no positive number
can be given. According to Suckow *, the heart of the pine caterpillar
( Gasiropacha pini) beats 30 times in a minute, but sinks down during
the pupa state to 18 pulses in the same space of time. In the just
disclosed caterpillar the pulsation is slow and irregular, but subse-
quently its rapidity increases so much, that it then makes from 50 to 60
pulses in the minute. Herold says that the pulsations- of the butterfly
increase the 'moment it commences to strike with its wings, and purposes
flying off, whereas he observed during copulation no alteration of its
quickness.

§ 240.

The assertion of a motion of the juices is founded upon observations
made upon the following insects.

Among the Dictyotoptera , all such larvae as live in water exhibit
it very distinctly. In the larva of Ephemera, a motion of the globules
of the blood has been observed in all the peripheric parts, which,
according to Wagener, extend even to the last joints of the antennae
and of the feet. This motion was slower the more the water evaporated
in which the larva was contained, but increased again upon the addition
of fresh water. The stream of all the peripheric parts collect into two
chief currents, which pass backwards on each side of the body, and send
off other currents to the exterior margin of the segments, but which
speedily return to the main branch after having passed through the
branchiae there situated f. Vessels inclosing these streams have never
been observed, and, indeed, the frequently partial change of course
distinctly proved the total deficiency of such organs. Individual cur-
rents have also been observed to extend even above and beneath the
intestinal canal, and to bend over to the main stem of the opposite side

* Anatomisch-physiol. Unters, über Insekten und Krustenthiere, p. 37.

■f Cams in the Nova Acta Phys. Med. vol. xv. Pt. 2, p. 8.

CIRCULATION OF THE BLOOD.

407

without being guided by a determinate canal, but, on the contrary, the
globules of blood evidently passed between the fatty body and other
internal parts. In the vicinity of each aperture of the heart portions
of the stream of blood bent over to the heart itself, and upon each
expansion passed into it, being received by those apertures. The
blood poured forth immediately from parts that were cut off, namely,
from the end of the tail, curdling into a thick greenish granulated
mass.

In the larvae of the Agrions there has been observed the motion of
the dorsal vessel, the lateral returning main currents, a stream running
upon the entire margin of the rudiments of the wings on the exterior
taking its course inwardly and on the interior returning, from which here
and there also globules passed in the contiguous passages between
the parenchyma of the wings, a powerful current also passes through
all the anal leaves, explained as gills, and flows inwardly upon the
under side of the central tracheae, but on the upper side again returns ;
and, lastly, a stream of blood is observed which advances in throbs,
and which probably flows from the anterior aperture of the aorta,
bending on each side to the eye, and thence proceeds beneath and back
again posteriorly.

In all perfect insects of this order, namely, in the wings of just-
disclosed Libellula (L. depressa ) and Ephemerce ( E . lutea and mar -
ginata ) Carus likewise saw a distinct motion of the blood.

Among the Neuroptera, those larvae which live in water exhibited
the same appearances. Distinct contractions were constantly seen in
the heart of the caddis-fly larva, which is divided into seven or eight
partitions and two lateral returning main streams, whence the globules
of blood passed into the apertures between the several chambers.
Several perfect insects also of this order, namely, Hemerobius chrysops ,
Semblis bilineata, and Semblis viridis , exhibited in their wings, and
the latter also in their antennae, a motion of the juices.

In those larvae which live in water, of many of the Diptera , namely,
of the gnats, Wagener observed a distinct pulsation in the dorsal vessel,
in which its contraction was visible in several of the chambers of the
posterior end. But even those very transparent larvae he observed, on
contrary, no motion of the globules of the blood. I myself, notwith-
standing having made several experiments, it is true with not very
perfect instruments, have been unable to detect such globules of blood.
In one instance, and also in a second similar one, namely, in the

408

PHYSIOLOGY.

larva of Notonecta glauca, Carus considers that the globules of blood
are too small to be seen through the microscope, and that it is from
this cause that the motion of the juices is not to be detected in the
body.

Among the Hemiptera, Wagener observed through the transparent
sides of the body of the young larva of Nepa cinerea distinct streams
of moving globules passing from the front backwards ; he could also
observe the pulsating dorsal vessel contracting in its chambers. In
the common bed bug ( Cimex lectularius) I have perceived the pulsa-
tion of the dorsal vessel, and also an indistinct motion of fluids at the
sides of the abdomen.

The remaining observations, chiefly compiled from Carus*, refer
chiefly to the circulation of the blood in insects not living in water.
Among the beetles, he observed it principally in the transparent
elytra and wings of Lampyris italica and splendidula, Melolontha
solstitialis and in a Dyticus ; then in the prothorax of Lam-
pyris splendidula. It here had the appearance of a strong current,
which came from the abdomen, and which, towards the end of the
pronotum, divided on each side into arms, that, upon each margin,
turned backwards In the Ortkoplera, on the contrary, he vainly
sought it in the wings, but Ehrenberg, according to the communication
of A. v. Humboldt, has seen a motion of the juices in a Mantis f.
The transparent wings of the Diclyotoptera and Neuropiera have
likewise here and there exhibited a motion of the juices, as well as the
wings of Libellula depressa, Ephemera lutea , E. marginata , Hemerobius
chrysops, but most distinctly in Semblis bilineata and in the antennae
of Semblis viridis. In the former, he saw the streaming blood pass
upon the anterior margin through the chief ribs, and distribute
itself upon the whole margin to the apex ; it returned back through
the ribs lying nearest to the posterior margin. Through the central
connecting transverse ribs, blood also passed from the proceeding to the
returning current. In the Hymenoptera , no motion of the juices was
perceived in the wings, and just as little in the Diptera In the
Lepidoptera, also, it still remains doubtful ; but Carus thinks he may

* Nova Acta Soc. n. c. C. L. vol. xv. Pt. 2, p. 1, &c.

f Bericht über die Natur historischen Reisen der H. H. Ehrenberg und Hemprich.
Berlin. 1826. 4to. p. 22.

\ In Eristalis tenax, Meig., and E. nemorum, M., I have recently observed blood pour
out of the roots of the wings during their motion, when the wing itself wfis cut off.

CIRCULATION OP THE BLOOD.

409

adopt a motion of the juices in the germen of the wings in the pupa of
some Lepidoptera, from the result of several of his experiments.

§241.

After such facts, I consider the asserted circulation of the juices as
proved. Carus was formerly inclined * to limit the circulation to those
insects still in their stages of development, and therefore concluded that
it disappeared upon their transformation into the perfect state. This
opinion he subsequently gave up +, upon being convinced of the contrary
by his own experiments; and it also is positively contradictory to the
generally adopted physiological significance of the circulation, for what
in this respect is the case in young animals, must also be found in old
ones. Indeed it is true that in many insects an alteration takes place
in the reception of food, and its quantity becomes less, and that thence,
consequently, there must be found in them a slower digestion as well as
a smaller quantity of separated lymph, but it must not be forgotten,
that, precisely at this last period, the compass of the body is smaller,
whereas its internal organs are larger, and that these have already
attained their perfect development, and require but a small addition to
be retained in action ; and that, lastly, the whole internal cavity of the
body presents less free space in which the stream of blood can be
distributed. These various causes appear to me to explain the decrease
of the circulation ; and indeed in the higher animals the pulse is lower
in age than in youth ; wherefore, then, should not the same relations
be found in insects ? But that a circulation is found in these creatures
in their perfect state, is proved by direct observation ; must these, then,
be considered as exceptions to the rule, and that which is the rule in all
other animals, form the exception in insects ? I see no foundation for
such a conclusion.

§ 242.

With respect to the physiological importance of the circulation in
insects, I conceive it consists especially in preserving a general motion
of the fluids, by means of which all the portions of it are subjected to
an equal deposition of oxygen. If the lymph passed through the
intestinal canal into the cavity of the abdomen, and remained there
stationary, those parts of it which encompassed the tracheae would

* Entdeckung, &c., p. 21. f Nova Acta Ph ys Med. vol. xv. Pt. 2, p. 14.

410

PHYSIOLOGY.

alone be oxidised ; and, indeed, the fluid would not pass equally into
the distant members, but that portion which once found itself in the
cavity of such a member would there remain without being equally
supplanted by fresh juices. But hy this progressive motion of the
whole body of juices this partial stagnation is prevented, and each
organ furnished equally with fresh juice fitted for assimilation. Both
the large streams of blood which run along and between the large
lateral stems of the tracheae, are constantly receiving fresh oxygen
from the tracheae, and carry with them the fresh lymph secreted by
the intestine, and then give off the freshly-oxidised blood to the heart,
which, by its rhythmical pulsation, conveys it on, and rejecting it by
the free orifice of the aorta, drives it to all the parts of the body. The
returning main streams, consequently, are comparable to the arteries of
the lungs, or rather, as in the Mollusca , to those large veins which,
collecting the blood from all parts of the body, return it through the
lungs or bronchiae to the heart. The passage of the oxidised blood
into the heart is occasioned by its expansion and contraction, which
takes place synchronally with the respiratory motion of the whole body,
and particularly of the abdomen, and these individual motions of the
heart are partially produced by its muscular tunic, and partially by the
muscles of the wings which bind it to the dorsal plates. The muscular
tunic of the heart contracts itself and makes the systole. The muscles
of the wings, by their contraction, again expand the heart, and produce
the diastole : when the blood streams in through the apertures and by
the former, it is driven into the aorta. Hence throughout the whole
body a constant oxidisation of the blood is taking place, as, even in
the most remote members, tracheae are distributed, and there oxidise
the juices they found. But these juices also do not rest, but participate
in the general motion. True venous blood is consequently deficient in
insects, and if both the lateral streams have been called veins, this name
is only so far tenable as there may be detected in it a returning motion
of the blood to the heart.

§ 243.

But how can a motion of the blood be imagined without vessels ?
This question absolutely appears of great importance, particularly as
Carus thought it necessary that there should be vessels in certain parts of
the body. This opinion, however, will necessarily be limited to the vessels

CIRCULATION OF THE BLOOD.

411

which are found in the ribs of the wings, and which we have mentioned
above. I detected such vessels in many insects which I then examined,
namely, in Dyticus tnarginalis , Copris lunaris , Philanthus pictus , &c.,
but I yet doubt, from more recent investigations that I have made in
the bright and partially transparent pupae of some capricorns, namely,
Prionus faber and coriarius, the correctness of my above mentioned
opinion. In the rudimentary wings of these pupae I saw with un-
assisted eyes perfect tubes as silvery-white glittering filaments con-
taining air. These tubes in the upper wing or elytron gave off no
branches, but ran undivided in a direct line from the base to the apex.
But at the extreme base they collected into two main stems, the one
of which takes its course at the anterior margin, and the other upon
the sutural margin, both originating at the thorax as a simple stem.
The anterior one has two and the posterior one four straight radiating
branches, which run parallely. The tubes of the inferior or true wing
were divided, but likewise also only towards the apex. They also
originated from two similarly disposed main stems, the anterior one of
which likewise sent off two and the posterior one four branches. I
could distinctly see this by means of a simple lens. Upon its inspection
with the microscope, these tubes were observed filled with air, which was
interrupted at certain parts, so that the tubes appeared to contain
disconnected air-bladders. I could not even yet detect by means of the
microscope the structure of the tubes, which was only visible upon
removing the external tunic of the elytron, and the tube then lay
distinctly in the parenchyma before me ; an extremely fine filament
was then seen, which wound itself spirally around the circumference
of the tube, and left a tolerably wide space between it. On each side
of these tubes there was a bright stripe, as if a channel lay free in the
parenchyma contiguous to the trachea. I now repeated my investiga-
tion in other insects which had been immersed for some time in spirits
of wine, but I found neither in the vessels of the elytra, nor in those
of the wings, a spiral twisting, and just as little in dried specimens.
Thence I might conclude that the spiral filament becomes invisible by
immersion in alcohol as well as by drying in the air, at least under
the microscopic power that was at my command, but that it never-
theless existed in all the vessels that take their course through the ribs
of the wing ; that consequently all these vessels must absolutely be con-
sidered as tracheae, and that blood-vessels are not to be found even in
the ribs of the wings.

41 2

PHYSIOLOGY.

Jurine’s* and Chabrier’s t observations upon the structure of the
wings harmonise herewith ; whereas, according to Carus, there is a
threefold difference in the structure of the wings with respect to the
vessels contained within their ribs. Some, as the elytra of the beetles,
have blood and air-vessels ; others contain only blood-vessels ; the third,
lastly, as the wings of the Hymenoptera and Diptera, exhibit air-
vessels exclusively. But according to my opinion and observation, these
differences do not exist, but all the ribs contain merely tracheae or air-
vessels, whereas within the rib^ around the trachea there remains a
vacant space in which the juices can freely circulate, and it was in this
free space that Carus saw, in all those |instances where he perceived a
motion of the blood in the wing, the globules pass and return.

Hence also is it that the wings derive their true significance. Oken
even indicated that the wings of insects were no true members, but
as mere continuations of the skin in which vessels were distributed,
they were of analogous importance to the gills, and he thence called
them air-gills ( luftkiemen ) But if now, as I believe it is, proved
that the blood actually flows through them, their function as gills is
placed beyond a doubt. The partial interruptions of the ribs, Jurine’s
bullae, are the places where the blood flows immediately beneath the
thin membrane, and can there even imbibe oxygen from the air, which
is, besides, presented to it everywhere by the tracheae around which it
circulates. Chabrier’s observation, also, that a space filled with
moisture is found in the under wings of the beetles §, is evidence that
blood flows in the wings, and such a stream can only pass through the
ribs contiguous to the tracheae contained within it.

If the supposed presence of blood-vessels in certain parts of the body
is thus contradicted, it may likewise be inferred of the whole body that
it has no blood-vessel excepting the large dorsal vessel. Indeed
Joh. Miiller considers that he has detected vessels passing from the
heart to the ovary ; but these connecting filaments, as we have shown
above, are no vessels. The proposition which I have just stated
is therefore proved correct to its full extent. Yet this deficiency of
blood-vessels in the bodies of insects is by no means so extraordinary,
nor is it without parallel. In the membranes also of the developing

* Nouv. M4th. de Classer les Hymenop Geneve, 1807. 4to. p. 48.

*j* Essai sur le Yol des Insectes. Par. 1822. 4to. p. 42.

X Natur. Philosophic, 2nd Ed. p. 418. No. 3337.

§ Essai sur le Yol, &c., p. 19.

CIRCULATION OF THE BLOOD.

413

embryo, the blood originally flows without vessels ; and only after the
stream has acquired some degree of regularity, do the vessels form
themselves around it. The same appears to be the case in the motion
of the juices in the lower animals. In these also the circulating fluid
forms for itself a passage through the parenchyma of the body ; it
grooves as it were a course for itself, in which it afterwards constantly
continues. This course is in insects attracted especially to the large
tracheae, because the vital air, that substance to which all blood must
attain, is transmitted through them. Were the thick tunics of a
vessel to be formed around it, the deposition of oxygen could not so
easily take place ; and indeed in insects it would have greater diffi-
culties to contend with than in any other class, for in them the
tracheae, even to their extreme ends, retain their hard spiral filament,
whereas in the vesicles and cells of the lungs and gills it disappears,
whence the oxygen can more easily pass through the delicate mem-
brane of the respiratory apparatus, and arrive at the likewise delicate
tunic of the blood-vessels ; but in insects it is more strongly retained,
and would be even more so if the blood-vessel also had a thick
membrane. It thence appears to me that the deficiency of blood-
vessels is necessary to the undisturbed corporeal functions of insects ;
their organisation merely required a central organ whereby the motion
of the juices is promoted, and by means of which it is regulated
and guided ; and this organ is their dorsal vessel. The course
through it being originally traced, and the first impulse to the mo-
tion of the blood being given by the spontaneous motion of the dorsal
vessel, the free stream of blood necessarily follows this direction until
it again returns within the sphere of the activity of this organ, and
is then again forcibly attracted to it, and, as before, involuntarily
driven into its preceding course.

414

PHYSIOLOGY.

THIRD CHAPTER.

THE METAMORPHOSIS.*

§ 244.

In the preceding chapters we have explained how the insect
originates, propagates, and subsists, without having noticed the several
stages of life it has to pass through, from the first origin of its being
until the time it is actively engaged for the preservation of its resem-
blance. We have indeed here and there drawn attention to the
differences which exist with respect to the mode of taking food and
its assimilation with the body between the undeveloped and the perfect
insect, but we have not yet explained the several successive periods of
development, nor shown their physiological character. This will be
the subject of the present chapter. We must now look around us for
the causes which determine the form of insects in general. We must
endeavour to ascertain why insects take this form and no other, and
exhibit a body thus composed of rings and limbs, and what necessary
changes a thus formed body must be subjected to, in order to maintain
its fundamental figure even through the several developments which
every organic, or, at least, animal being, is obliged to pass through.
But as an introduction to this investigation, we must prelude with
some general observations, which refer to the differences of all animal
forms, that we may be in a situation to discover from the differences of
these forms, the shape of insects and the object of this shape from their
opposition to the rest, and then only, when the cause of the articulated
body of insects is discovered, can we proceed with the consideration of
the several transformations peculiar to it.

§ 245.

The animal kingdom, like all organic matter, the essential character
of which is expressed in the idea of becoming or having become,
traverses a certain series of grades of development, upon which it

* In this chapter the §§ 245 — 248 and 251 have been entirely rewritten by the author,
and the former §§ 248 and 249 have been changed into the present §§ 249 and 250 — Tr.

THE METAMORPHOSIS.

415

ascends from its first simple beginnings to its highest perfection.
Nature attains these developments by antitheses. The immediate con-
sequence of such an antithesis, and which is visible in the homogeneous
mass of the body, is the antithesis between the interior and exterior,
whereby the internal cavity of the body which prepares the nutrimental
matter stands in opposition to its external surface, which con-
ditionates its form ; the further perfection of this first antithesis,
developes the various organs which stand in connexion with those two
organic systems. Thus from the originally simple digesting cavity of
the body, by degrees the intestinal canal and its various appendages
promoting digestion, viz. the glands, are formed ; and from the originally
uniform integument of the body, on the contrary, all those organs are
produced which promote and effect motion. The correctness of these
assertions is deduced from the history of the embryo forming in the
egg. Thus there appears in the several grades of development of the
animal kingdom, as it were a rivalry between the internal nutrimental
organs and the external organs of motion, and it therefore may be
readily imagined, in the varied direction Nature has pointed out for
its creatures to pursue, that in some animals the perfection of the
internal organs, and in others that of the external ones, has been
especially promoted. We call all those animals in which the first is
visible, namely, a prevailing development of the intestines, ventral
animals ( Gastrozoa ), but those in which the external organs attain
the greatest perfection, limb animals ( Arthrozoa ).

But the highest perfection of the animal kingdom is by no means
attained by these two grades of development, for both as partial
developments must still appear unperfected. There only is the highest
perfection attained where the external as well as the internal organs
are equally perfected, and both have acquired their highest grade of
development. That this highest development appointed by nature for
the animal kingdom may be attained, there must be a third chief
group in the animal kingdom, the members of which make themselves
apparent by this homogeneous perfection of the external and internal
organs. We have long known this third group by the name of
vertebrate animals ( Osteozoa or animolia vertebrata) .

The individuals of the animal kingdom which belong to these several
chief groups, it is easy to discover from the above character of each
group, and which the following Table exhibits : —

416

PHYSIOLOGY.

i. Group — Gastrozoa. The following classes belong here :

1. Infusoria polygastrica. Ehrenb. 2. Polypina sive
Corallina. 3. Medusina. 4. Ecliinodermata ►
5. Mollusca. Cuv.

ii. Group — Arthrozoa. Here belong the classes :

6. Endozoa. Annulata. 7- Rotatoria . Crustacea.
8. Myriapoda. Arachnodea. 9. Insecta.
hi. Group — Osteozoa :

10. Pisces. 11. Amphibia. 12. Aves. 13. Mammalia.
§ 246.

The forms of the thus discovered three chief groups of the animal
kingdom are adapted precisely to their internal organisation. The
first group possess a figure conformable to its organisation, namely,
that of a bag or sack, that it may receive in this sack its various
organs. In the highest animals, also, the same organs which in
animals of the first series are especially developed, also lie in large
cavities and bags, that are formed almost exclusively of soft parts. The
second group, which is constructed upon the predominant development
of the organs of motion, exhibits an elongate form, generally divided into
segments and limbs. Herein also they correspond in form with the
same organs of the higher animals, which characterise the second
series in the development of the animal kingdom, namely, the members,
which, as well as them, are elongate, and consist of joints and conse-
cutive divisions. The third group, consisting of the conjunct contents
of both the others, has a form partaking of that of both ; their bodies,
consequently, appear as central bags and cavities, whence the peri-
phrastic subdivided members proceed. They thus, therefore, repeat
the forms of all the other animals ; indeed, their form is, as it were, a
compilation of all other animal forms.

§ 247.

Insects, consequently, by reason of the predominant development of
their organs of motion, belong to the elongate animals, divided into
segments and divisions. By means only of such a structure is free
motion possible. One limb pushes itself forward, affixes itself, and
draws the other after it ; the alternating, affixing, and quitting is
repeated then by every successive limb, and thus the general motion of

THE METAMORPHOSIS.

417

the body is produced. In some worms, therefore, we can admit but
of two limbs, namely, an anterior one, in which the mouth lies, and
which, by the suction of the mouth, affixes itself, and a posterior one,
which possesses the sucking cavity, and which, by the help of this
organ, can attach itself. In the Annulata , which consist wholly of
rings, for instance, the earth worm, small setae supplant the sucking
cup ; in the higher Annulata , these setae develope themselves into feet,
which remain in the Crustacea , Myriapoda, Arachnodea, and insects ;
in the last, organs of flight are superadded. Thus insects maintain,
in accordance with the law of successive development, the highest
grade among all annulated animals or Arthrozoa.

§ 248.

It therefore appears that, in the further development of the three
chief grades of the animal kingdom, the place of abode and the thence
proceeding influence of the external world (the external medium)
has a very peculiar effect upon the animal organism. There are,
however, but three differences of abode, which are the water, the
earth, and the air. But in these three chief groups of the animal
kingdom, particularly in the second and in the third, we find three
groups subordinate to these chief groups, which are determined
by the places of abode. Amongst the Vertebrata these groups have
long been known as classes ; and are called fishes, as water-verte-
brata ; birds, as air -vertebrata ; and mammalia, as earth-vertebrata.
To these a fourth class is associated, that of the Amphibia, which
apparently is not to be arranged with them, but which, however,
presents itself as highly necessary. The living in water, air, and
earth are, notwithstanding their great resemblance to each other, so
strikingly different, that the animal organism cannot pass directly from
one grade to the other, but it requires a connecting member, wherein
the organisation is adapted to a residence in both elements, From this
transition I have called all such classes — classes of transition.

The group of Arthrozoa admit of being separated in the same
manner, if the division may be deduced from the mode of their develop-
ment. We obtain thus, therefore, in their four classes : —

1. The Water-Arthrozoa. Comprising the intestinal worms

( Endozoa ) and the Annulata.

2. The Class of Transition. Here stand, as the direct

links of transition, the wheel animals ( Infusoria rotatoria ,

E E

418

PHYSIOLOGY.

Ehrenb. ) and the crustaceous Arthrozoa ( Crustacea ,
formerly called Malacostraca by me, not the Malacostraca
of Leach).

3. The Earth- Arthrozoa. Here are arranged the Myriapoda

and the Arachnodea (or Arachnides ).

4. The Air-Arthrozoa. Which comprise the hexapod insects

( Insecta ).

Each of these groups has a peculiar organ whereby it is characterised,
and as the general character of the Arthrozoa is expressed in the pre-
sence of organs of motion, we shall necessarily have to seek for the
characters of the subordinate groups among those organs. The character
of the worms or water -Arthrozoa is, that in them we first observe the
presence of distinct organs of motion, but which yet are of no deter-
minate type, and which, therefore, sometimes present themselves as
sucking cups upon the head ( Cestodes ), or upon the head and belly
( Trematodes ), or upon the head and contiguous to the arms ( Hirudinei ),
then as setae ( Naidei , Lumhricini sive Chcetopodes ), and, lastly, as
short pedal warts with hooldets ( Annelides antennati, Lam.). In the
following class they transform themselves partly to swimming organs
(the rowing organs) and partly to jointed swimming and coursing feet,
both of which forms are simultaneously common to the majority of
Crustacea. In the earth- Arthrozoa the limbs are conformably shaped,
feet adapted only to running ; in the air- Arthrozoa, or insects, we
first find wings as the organs of motion for this element, they possess also
legs for running and exercising other functions like the earlier ones.

§ 249.

Is the law indicated by the earlier physiologists, and applied by
Oken, especially, to the natural system, correct, that the higher groups
are repetitions of the lower ones in their development ; or must we
rather, with Yon Bär *, thus explain it, that the development of every
class of animals admits of recognising the progressive perfection of the
animal body as well by morphological as histological separation, as
also by the progressive construction of a particular form from one
more general ? In either case it will necessarily be applicable to the
development of insects. It is evident that both propositions tend to

* C. v. Bär über Entwickelungsgeschicbte der Thiere. Königsb. 1828. 4to. vol. i.
p. 231.

THE METAMORPHOSIS.

419

the same point. No one who speaks of the embryo of man passing
through the lower grades of the animal kingdom can have imagined that
man at any period was ever of his embryo life an infusorium, polypus,
muscle, snail, worm, crab, spider, insect, fish, turtle, snake, lizard, and
bird ; but the assertion is nothing more than that man as man has once
in the progress of his development been upon that grade upon which the
several classes beneath him remain stationary in the progressive deve-
lopment of the entire animal kingdom ; and Von Bar’s proposition
expresses precisely the same thing, for in the successive development
of the animal kingdom there is found, just as in the development of
each individual animal, a progressive morphological and histological
separation as well as the gradual formation of a peculiar shape from
a more general one. The most general form of the Arthrozoon, as
which we have found the insect, is a body that is divided into rings
and segments ; and insects, therefore, must present us in their develop-
ment both with a progressive formation of a particular shape from this
more general one, as also with the morphological and histological
gradual perfection of their individual organs. The series of Gastrozoa,
as I succinctly call the first series, are, on the contrary, only so far
repeated by insects in their development as they themselves in their
own development have for object the progressive perfection of the
nutritive and propagative organs. This repetition, however, does not
extend to the external form, for this is the result of a new development
not yet visible in the Gastrozoa ; whereas the vertebrata which unite
in themselves both forms, viz. that of the Gastrozoa as well as of the
Arthrozoa, exhibit also formal approximations to the Gastrozoa in
their development. Only so long as it remains in the egg- case is
every insect a Gastrozoon, for it then has no other organs than the
nutrimental ; but upon quitting the egg-shell it becomes an Arthro-
zoon, and exhibits itself in its then appropriate jointed shape.

§ 250.

Hence, therefore, the essential character of the metamorphosis of
insects is found in the repetition of the lower grades of the Arthrozoa
by means of the development of the highest. No single class of
animals, we might say, confirms this repetition more distinctly than
insects. The maggot, caterpillar, or larva which creeps out of the egg
is of the same form as the earth-worm. Some of these maggots are
footless and headless, and move like the leech by affixing the first and

e e 2

420

PHYSIOLOGY.

last segments of their body,, in which, indeed, no distinct sucking-cups
are visible, but merely wart-shaped stumps of feet, at least upon the
last. This form, which we observe in the larvae of most of the Dipteraj
is consequently the lowest of all. And, indeed, what is still more, not
merely in the organs of motion, but also in the mouth, do they resemble
each other, the former, like the latter, possessing short hard-pointed
puncturing instruments, with which they pierce their food and then im-
bibe it. The second grade of larvae, namely, those maggots which are
provided with a head, but are without feet, as, the larvae of the Hy~
menoptera, and of many beetles, repeat another grade of the Annulata,
in which, as in Nais, there is a distinct head, but the feet are wanting.
The third grade of the Annulata , namely, those which reside in tubes,
and are furnished with large bundles of gills, find, among insects, their
representatives in those larvae of the May and caddis-flies, which dwell
in cases and breathe through gills. The fourth grade of Annulata , as
Nereis, Eumolpe, Aphrodite , &c., has, besides a distinct head, many
feet on the ventral side of the segments, and their analogies are, among
insects, the caterpillars of the Lepidoptera , and those larvae of the beetles
which are furnished with feet.

In the pupa state, the insect advances into the class of the
Malacostraca. Just as the pupa state is a mere transition in the
life of the individual, so also is the class of Malacostraca a true
transition group in the development of the Arthrozoa, for the Arthrozoa
contained in it strive to detach themselves from the life in water to
elevate themselves to the life in air. Thence arise the innumerable
different forms, and, indeed, the greater difference between the indi-
vidual organs found in them more strongly than elsewhere ; with perhaps
the exception of the amphibia, which stand in the same relation to the
vertebrata : and the advance from the life in water to the life in air is
nowhere observed more distinctly than in the order of the Malacostraca.
The Crustacea are true water animals ; they all live in this element,
and, quit it rarely and as an exception. The Myriapoda stand upon
the confines between the water and earth-dwellers : some incline to the
former and others to the latter. The Arachnodea, lastly, are true
earth-dwellers, particularly the scorpions, but some true spiders seek
the air as their medium, for they distend their web upon elevated
sunny places, and, floating in it, seem to endeavour to revel in the
purer air ; and, indeed, a few raise themselves upwards in the air, for
instance, A. obtectrix, which is raised by the wind upon its self-formed

THE METAMORPHOSIS.

421

clouds, and swims in the fluid element. The majority are inimical to
water : a few only seek it and dwell in it.

A very similar series of developments to those just observed in the
Malacostraca, do we find in the pupa of insects with a perfect meta-
morphosis. The lowest, as the pupa of the gnats, some other Diptera,
and the Phryganece, breathe like the Crustacea through gills, but
their number is small compared with the large order of the Crustacea ,
which thence proceeds that they merely briefly indicate this order,
and are not intended fully to repeat it. All other pupa breathe through
spiracles. Some of them, as the pupae of the flies, crepuscular moths,
and beetles, lie in the earth ; they represent the Myriapoda, of which
many but rarely visit the light of day, but dwell beneath stones and
in other shady places. The pupae of the butterflies and Noctuce seek,
on the contrary, the air, particularly those which hang themselves
freely in the air, that they may enjoy it upon all sides. Those that
are affixed may, lastly, be compared with the spiders that float in their
webs.

With respect to their internal organisation, the imperfect simple
tubular form of the entire intestinal canal, the predominance of the
circulation in all parts, as well as the mere rudiments of the sexual
organs, evince the analogy of the larvae to the- Annulata. The per-
fecting of the intestinal canal during the pupa state, particularly the
formation of the proventriculus at this period, and, lastly, the more
distinctly developed sexual organs, although the latter conditionates
no significant external difference, still further prove the analogy of
the pupa and the Malacostraca.

We have thus shown the repetition of the lower grades in the
development of insects with a perfect metamorphosis. But this entire
repetition has been expressed by Oken in the following words * :
“ Every fly creeps as a worm out of the egg ; then by changing into
the pupa, it becomes a crab, and, lastly, a perfect fly. ”

§ 251.

We have as yet taken no notice of insects with an imperfect
metamorphosis, and, indeed, because they are not subjected to the law
of repetition or analogy which is so distinctly expressed in insects with
a perfect metamorphosis ; for moulting is no metamorphosis, although

Naturgeschichte für Schulen, p. 577. 9th Class and pp. 581, 583.

422

PHYSIOLOGY.

the form of the body is somewhat changed; besides, all other Arthrozoa
are likewise subjected to this moulting. They differ from the remaining
Arthrozoa, namely, from those of the third group, merely by the pre-
sence of new organs of motion peculiar to them, and the presence of
these organs constitutes really their physiological and philosophical
character. But insects with a perfect metamorphosis likewise present
this character and a second one in addition, namely, the repetition of
all the earlier forms of the Arthrozoa during their period of development.
It is a positive fact, confirmed by the history of the development of all,
especially of the vertebrata, that the degree of perfection of an organism
or organ is the greater the more numerous the grades of development
are which it must traverse to attain its full perfection. If we apply
this law to insects, it follows incontestably that insects with a perfect
metamorphosis must be placed higher in the series of animal bodies than
insects with an imperfect metamorphosis.

We may now ask, why was such a difference of insects from each
other necessary ? Why could not all develope themselves, and propa-
gate in the same manner ? To this we may reply — Nature endeavours
to make every possible use of the means which she has conceived
allowable for the variation of a determinate type, that is to say, all the
forms that are elaborated by the normal progress of development, she
absolutely creates and produces as independent creatures. This law,
which we find everywhere confirmed, will furnish us with a key to the
necessity of a difference among insects with respect to their metamor-
phosis. I refer for this purpose to the four chief classes of the Arthrozoa ,
each of which is characterised by its place of abode and the possession
of peculiarly formed organs of motion, and we already saw above that
the presence of wings in any of the Arthrozoa suffices to raise it to the
class of insects. But we also perceive that Nature, if she will derive
differences merely from the organs of motion, possesses no further
means to found new variations, for she has already exhausted the
forms of these organs. Whence, then, should she obtain means for the
attainment of her object of producing the greatest possible variety, if
she did not resort to the last, which is the repetition of the earlier forms
in a higher grade of perfection ? She, therefore, avails herself of
this, and allows one portion of insects to be distinguished from all
the other Arthrozoa merely by the presence of wings, whereas the other
portion of already winged insects she raises so above the preceding, that
she conducts them, before they arrive at their final stage, through the

THE METAMORPHOSIS.

423

earlier forms of the Arthrozoa, which have remained stationary upon a
lower grade, and, at a certain period of their lives, furnishes them with
merely pedal warts, then with hooked, short feet, then with branchiae
and natatory laminae, and, later, in their pupa state, with rudimentary
wings, and, lastly, with perfectly developed wings. Thus I conceive
to be explained the necessity of both the chief groups among insects.

In insects with an imperfect metamorphosis there cannot, conse-
quently, be a passage through the earlier forms and grades of the
animal kingdom ; even the analogy which I formerly thought I detected
between them and the consecutive classes of the Gastrozoa, appears to
me now, upon a closer investigation, to be a merely playful endeavour
to discover resemblances, and which I consequently no longer value.
What I formerly, as a proof of such a repetition, deduced from the
successive development of the sexual organs, may, with equal justice,
be applied to all insects, or to all Arthrozoa, and, indeed, to all animals
whatsoever, in as far as in all, the perfecting of the genitalia progresses
with the gradual development of the creature.

Nevertheless, all insects, notwithstanding this difference from each
other, must be recognised as members of the same class, and, indeed,
by reason of the uniformity of the figure of the whole body, that is, by
its division into three chief parts. This division of the body, which,
among all the Arthrozoa, is peculiar to insects alone, is their second
most important truly physiological character, which proves the equali-
sation of the contention between the various organs of the body, and in
the limitation of each individual organ to a particular and impassable
sphere of action, most clearly illustrates the fixed laws of its type of
structure, which is^always a predominant character of highly developed
and perfected groups. The same law exhibits itself in the structure
of the mouth, the antennae, the wings, and, especially, in the number
and articulation of the legs, whence their number, restricted to six,
has always been considered as the safest character of insects.

§ 252.

Having thus explained the significance of the insect metamorphoses,
it still remains for us to define distinctly the several changes which the
insect undergoes during these stages. Indeed, in the anatomical descrip-
tion of the organs of digestion and generation, we have already spoken
of the changes they experience during the metamorphosis (§114 and
§ 153) ; but these changes have not yet been brought into connexion

424

PHYSIOLOGY.

with the other transformations of the body ; and, besides, we have not
yet at all spoken of the great discrepancy of the form of the limbs, nor
even of what is still more important, namely, the addition of new ones.
In the explanation of these subjects which we are now entering upon,
the insects with a perfect metamorphosis will chiefly occupy us, in so
far as in them only does a true transformation take place ; whereas we
shall speak of the insects with an imperfect metamorphosis only where
we take notice of the moulting, and upon our investigations into the
sprouting of the wings. We shall here, therefore, have an opportunity
of circumstantially referring to that law laid down by Von Bär, that
there is visible in the development a perfecting as well by the means of
morphological and histological separation as by the progressive forming
of a particular figure from one more general.

If an Arthrozoon, whose form consists of a longitudinally distended
and generally hardened case, composed of limbs and rings, is to enlarge
by growth, it must strip ofF its former covering and clothe itself with a
new one, as the old one interrupts the universal distension, and, indeed,
makes it wholly impossible. It is only in those Arthrozoa which dwell
in moist places, so that from their place of abode their integument
cannot harden in the air, which, therefore, constantly remains equally
soft and flexible, the casting of the external integument is rendered
unnecessary, and they therefore do not moult, but even in the higher
Annulata, for instance, in the leech, a moulting is observed, and still
higher, for example, in the Mctlacosiraca , it is the necessary condition
of growth. In insects, also, this change of skin must likewise take
place so long as they grow, and it is this change of skin alone which, in
insects with an imperfect metamorphosis, presents itself as the external
mark of metamorphosis ; but it is also proper to insects with a perfect
metamorphosis, among which it indicates, as well as among the preceding,
a transition from one stage of life to another.

The earlier physiologists differ in opinion from the moderns upon
the mode in which this new skin originates beneath the former.
Swammerdamm and Bonnet were of the opinion, in accordance with
the general idea of their age of the theory of encasement, that all new
skins already existed beneath the old one, and that the latter, without
any re-production upon the part of the larva, was merely stripped off.
Exclusively of the true object of moulting being overlooked in the
adoption of this opinion, the mere observation of the larva having con-
siderably increased in size immediately after the divestment, contradicts

THE METAMORPHOSIS.

425

it ; for if the new skin already existed beneath the old one, must it not
there exist in considerably smaller compass rather than in larger ?
That Kirby and Spence could adopt and explain this opinion as the
most correct, distinctly fixes their position in physiology, which, not
merely here, but almost everywhere, exhibits itself as an antiquated
one. Whereas, according to Herold’s* admirable observations, there
is not the least trace in the young larva of the new skin, but this first
originates towards the end of the first period of the caterpillar’s life, a
few days only before the old one is stripped off. It is then observed
that the mucous and muscular layers of the skin separate all round
from the epidermis, and then clothe themselves upon the superior
surface with a new epidermis. The development of this new external
skin occupies two or three days, during which the caterpillar appears
sickly and takes but little or no nourishment. Lastly, the old skin
divides longitudinally along the back, and the caterpillar frees itself
from its now separated skin by means of contortions and violent
motions, first emancipating its head and then drawing the body out.
The epidermis, all the external visible organs, and even the mandibles
and palpi, remain attached to the old skin. Upon the caterpillar
having quitted its old case, it appears very languid, its body is soft and
easily injured, so that during its change of skin even a slight pressure
is sufficient to kill or wound them, but it speedily resumes its former
strength, and it then devours with renewed voracity, as if eager to make
up for lost time. Contemporaneously with the formation of the new
skin, the intestinal canal has also enlarged, thence after its moulting
the quantity of food becomes greater, the digestion more perfect, and
the formation of the fatty mass is more rapid and in larger quantities.
In general, this first moult takes place about the twelfth day of the
life of the caterpillar. The second moulting, which occurs after another
lapse of from six to eight days, presents the same phenomena, and has
the same effects ; and the third also, which takes place after another
six or eight days. But its voracity constantly increases, so that a
larva does not now merely consume three or four times its own weight
of food, but it also increases considerably in corporeal mass ; as, for
instance, the comparative weight of a full-grown caterpillar of the goat
moth to that of the young one just crept out of the egg is, according to
Lyonet, as 72,000 to 1. A growing flesh-fly takes in twenty-four

* Entwickelungsgeschichte der Schmetterlinge, p. 26, &c.

426

PHYSIOLOGY.

hours 150 times its own weight ; but the common caterpillar of Euprepia
Caja, which weighed thirty-six grains, and every twelve hours rejected
from fifteen to eighteen grains of excrement, increased only one or two
grains in weight in the same space of time *. The increase in weight
appears to be much greater in carnivorous larvae, for, according to
Redi t, the maggots of the flesh-flies, which at first weighed one grain,
,so increased, that each, on the following day, weighed seven grains,
which gives a proportion of increase, in twenty-four hours, of from
1 to 200.

After the third moulting, when the larva has acquired its full size,
the rudiments of the wings begin to form beneath the skin, upon the
first and second segments. They at first present themselves as short
viscous leaves, the substance of which greatly resembles that of the
mucous tunic, and to which many delicate tracheae pass, which dis-
tribute themselves throughout them. These rudiments increase with
the growth of the caterpillar, and betray themselves, even externally,
by both the segments of the caterpillar, upon which these rudimentary
wings are found, appearing swollen and spotted. Their enlargement
probably takes place by the assistance of the blood flowing into them.
Simultaneously with the perfecting of these rudiments the intestinal
canal increases in compass, and, as a consequence of this increase there
is a greater accumulation of the fatty mass. A transformation is also
taking place in the anterior feet of the caterpillar, for the larger legs
of the butterfly begin to form. But, as a similar transformation is
going on in the oral organs, the caterpillar loses its desire to eat and
power of mastication, it ceases to receive food, and prepares itself for
its last moulting, viz., for its change into the pupa. It seeks for this
purpose an appropriate place where it can lie, hang, spin, or attach
itself, and it accomplishes this, its last business, the same as its earlier
ones, with great care and consideration. After its situation and web
are prepared it reposes a few days, then strips off its skin, and now
presents itself as a pupa, with the visible limbs of the butterfly.

It is striking that insects, notwithstanding such a great, and, we might
almost say, unexampled, capacity of production which is exhibited both
in their rapid growth and the increase of the body in mass as well as
in the development of new parts and the enlargement of the old ones
during the pupa state, display but very slight traces of a power of re-

Kirby and Spence, vol. i.

f De Generat. Insectorum, p. 27.

THE METAMORPHOSIS.

427

production. Beckmann * and Goeze t have imparted experimented the
results of which are — that the former, in Agrion virgo, and the latter in
Semblis bicaudata, Fab. ( Perla , Geoff.), once observed a leg, which
was smaller than the rest, whence Goeze concludes that this leg must
have been lost, and subsequently replaced by a new one. To these
former observations we may add some more recent ones of Heineke J,
wThich are absolutely of greater importance. On the 25th of July he
cut off both the antennae of a Blatta Madeirce, after which it moulted
on the 8th of August, and now acquired two new, but much shorter
ones. He repeated the same experiment in the pupa of a Reduvius ,
where he obtained the same result. In perfect insects also, subject to
no further moulting, namely, species of the genera Forjicula, Gryllus,
Locu.sta, and Acridium , he mutilated in the same manner, but even in
the space of two months they acquired no new limbs, but cast off the
old ones shortly after they were injured. These results entirely har-
monise with the reproduction of the spiders ; these also renew their
lost limbs only so long as they yet moult, whereas after their last
moulting they cast off their mutilated ones, but acquire no new ones.
We must, therefore, ascribe to insects, at least to those with an imperfect
metamorphosis, the power of replacing lost limbs, with these restric-
tions. It does not appear to be different in insects with a perfect
metamorphosis, for mutilated caterpillars are said to obtain new limbs,
that is to say, legs, after the next moulting. But it is remarkable that
these limbs do not germinate whilst the insect remains in its old case.
I think this circumstance is explained by the hardening of the integu-
ment, whence it is to be considered as it were dead, and thence I deduce
the reason of the known fact, that wounds given to insects cicatrise
only upon the next moulting, and consequently never in their perfect
state. It must also be attributed in a great measure to the deficiency
of blood vessels, for by their assistance cicatrisation and the resupply
of flesh is promoted, namely, the constant streaming of the blood to
the wounded spot, is the first cause of its subsequent living recon-
nexion. By means of the blood the lips of the wound are stuck
together, and hence is formed the cellular tissue which unites the
divided parts. Both blood and cellular tissue are consequently the
means which nature makes use of to replace lost or divided animal

* Physinkalisch-cekonomische Bibliothek, vol. viii. p. 20.

f- Naturforscher, part xii. p. 221.

X Isis, 1801, p. 1359. From the Zoological Journal, vol. iv. p. 422.

428

PHYSIOLOGY.

parts ; and now* as the first stands upon a very low grade in insects,
and the second is wholly deficient, consequently a cicatrisation of
wounds can never be effected. But if beneath the wounded skin a
new one is formed it uninterruptedly covers the wound of the old one,
and after moulting the larva appears healed, if the wound be not of a
description to affect its life, and thus interrupt all future changes of
the skin.

§ 253.

In our representation of the metamorphosis we have omitted one
phenomenon which was mentioned in earlier parts of the work (§ 114 —
127), namely, the simultaneous moulting of the intestinal canal and
tracheae, with that of the external integument. Bonnet * and Swam-
merdamm f, the first physiologists of their age, especially with respect
to the class of insects, maintained this opinion, and from their works
it has passed into those of modern physiologists ; whereas Herold, in
his history of the development of the butterfly, says, that such a change
of the tunic of the intestinal canal never happens, and that in the tracheae
it occurs only in the large main stems {. In fact, we must confess that
if the stripping of the skin is, as we have above remarked, merely
caused by its gradual hardening in the air, and the consequent impos-
sibility of the distension of the increasing body, it does not require that
we should thence admit of an equally requisite change of the internal
tunic of the intestinal canal, nor even of the tracheae, except in their
large main stems, into which much air passes, and that, therefore.
Bonnet's assertion reposes either upon a false observation, or was per-
haps wholly invented by him for the support of his theory of encase-
ment. But in opposition to this, independent of the credibility to
which a man like Bonnet may lay claim, the testimony of Swammer-
damm speaks, and who certainly did not lie, or say more than he saw :
he remarks, that at the posterior end of the stripped skin, where it is
twisted up and folded, he observed the moulted colon, and that after
the moulting of the larva of the rhinoceros beetle the internal tunic of
all the tracheae, even to their most delicate extremities, were visible in
the stripped integument §. I have distinctly observed the same in the
moulting of the Libellulce ; in these, not merely the main stems, but

* Contemplations de la Nature, tom. ii. p. 48. »}■ Biblia Naturae, pp. 129, 134, 239, &c.

+ Pp. 34. and 88. § Biblia Naturae, p. 129, b.

THE METAMORPHOSIS.

429

also many auxiliary ones, were divested of their tunic, and likewise the
internal tunic of the colon remained attached to the peeled case. We
have likewise above drawn attention to the uniformity of the external
epidermis with the mucous tunic of the internal organs, and by a
similar pathological phenomenon, shown their affinity. Thus, the
observations of equally credible witnesses and the several theories clash
together. It is difficult to discover the truth in the midst of such con-
tradictions. To conclude that in one order such a changing of the
skin exists, but not in the other, appears inadmissible, as nature in
general pursues in its process of development a certain uniformity.
Perhaps, however, we may find an outlet if we adopt that in smaller
individuals the internal tunic of the intestinal canal is more easily
absorbed, whereas in the larger ones, furnished with a coarser mucous
membrane, it is rejected. Many observations speak in favour of such an
absorption, namely, the absorption of the mucous membrane of the egg-
tube at its lower extremity, where it stands in connexion with the
oviduct after it has developed the lowest egg at this spot, and then has
passed into the oviduct itself (§ 210). But the perfect explanation
and determination of this doubt remains still as the problem of careful,
prolonged, and comprehensive experiments and observations.

§ 254.

The number of moultings of the larva until its full growth appears to
vary considerably in different families and genera. “ It may be
assumed in general that they change their skin three times. This is
the case in all insects with an incomplete metamorphosis. After the
first change the larva has merely increased in size, but during this
second period of its existence the rudiments of the wings form beneath
the skin ; consequently, after the second moulting, these incipient wings
present themselves externally as small leaves, which cover the sides of
the first abdominal segment ; these larvae are called nymphs it
being analogous to the pupa state of other insects. When this pupa
again moults the insect attains its perfect condition ; the at first short,
soft, thick wings spread in the course of a few minutes to their future
full size, then speedily dry in the air, when the at first distinct circu-
lation of the blood in the ribs gradually disappears, and the metamor-
phosis of the individual is completed. It raises itself with difficulty

* The passage in inverted commas is a MS. alteration from the original, commu-
nicated by the author. — Tr.

430

PHYSIOLOGY.

in the air by means of the first strikings of its wings, which succeed
but imperfectly, and it then seeks a more elevated spot whence to
exercise its new function with fuller effect.

Some genera, which from their abode in water prior to this period,
make a transition to living in the air, form in a remarkable manner a
perfect exception to the law, that with the casting of the pupa case the
metamorphosis of the individual is concluded. It is universally known
of the Ephemer a, that in about half an hour, and indeed frequently
only some minutes, after they have quitted the pupa case, again moult,
and then only are able to copulate and procreate. This observation
may be repeated without the least trouble in July and the commence-
ment of August, when the Ephemera in watery situations quit the
water towards evening by myriads. The just excluded Ephemera
flutters immediately, although with difficulty, out of the water, and in
the course of a quarter or half an hour, but in the smaller species in a
shorter space of time, it seeks an elevated object, for instance the stem
of a tree, the post of a bridge, houses that are close at hand, and
even individuals standing upon the bank, and here clings firmly with
extended legs. Speedily afterwards the dorsal case splits in its middle,
upon which the insect with violent motion first frees its head and
anterior legs from the old skin, which is succeeded by the other legs as
soon as the anterior ones have affixed themselves, and then at the same
time, but gradually, by the wings and abdomen. Prior to this moult-
ing the creature has not acquired its usual markings and dark colour,
which we perceive immediately after the new change of skin ; and it is
also remarkable, that after this change all the limbs, particularly the
longer anterior legs and anal setae of the male, become both more
slender and longer than before. The horny case of the eyes is the only
part which does not participate in this moulting. An analogous pro-
cess is found to take place in the pupa of the Phryganece and Semblodes ,
which in that state repose without taking food, and are consequently
endowed with a perfect metamorphosis, for, according to De Geer *, it
quits its place of repose, beneath the water, and creeping up the sides
higher than the surface, there casts its pupa case. I am inclined to
surmise from my own, indeed not fully comprehensive observations,
that the already perfected insect creeps forth, and then reposing for a
time, moults a second time. During this repose the wings especially

■f* M4moires sur l’Hist. des Insectes, tom. ii.

THE METAMORPHOSIS.

431

are formed, which in the just excluded insect possess but half their
size, but fully develope themselves after this renewed change of skin.

Among insects with a complete metamorphosis the caterpillars of the
butterflies moult, according to Kirby and Spence *, frequently ; but
thrice, according to Cuvier f . After the last moulting they become
pupae, and after the casting of the pupa case butterflies. The cater-
pillars of the Noctuce, on the contrary, moult four times, but some of
the large ones, which live for two years as caterpillars, much more fre-
quently, for instance, Euprepia villica, from five to eight times ; Eu-
prepia dominula, nine times ; and Euprepia caja, ten times J. The
time between two moultings also varies much, which appears to depend
partly upon the size of the insect and partly upon its length of life.
The larger ones require a longer and the smaller ones a shorter period.
In general the interval between two moultings varies from eight to
twenty days, excepting that those Lepidoptera which change into pupae
late in the summer or autumn, then lie the whole winter as pupae, and
are only fully developed upon the following spring. These pupae change
their larva-skin very early, mostly in the course of a few days, whereas
others remain long in it. This is the case in the larvae of the Tenthre -
donodea ; even after the pseudo-caterpillar has spun its cocoon, it still
remains for some weeks in its old skin, and only shortly before its time
of exclusion does it strip off its dried up larva case. This is at least the
case in the genus Cimbex, but in the smaller Tenthredos, for instance in
Lophyrus, in which the pupa state is of short duration, the larva skin is
earlier cast. Some larvae, namely, the maggots of many of the flies,
( Estri , Syrphodea, and Notacantha change into pupae in their larva-case.
All these larvae likewise possess the remarkable peculiarity that they do
not moult, but retain their old skin from the commencement of their
existence. It is in connexion with this peculiarity that we observe the
stronger folding of their external tunic, as also their abode in damp situ-
ations ; some larvae of the Syrphodea alone, namely, the larvae of Syr-
phus , which prey upon the Aphides , make an exception to this dwelling-
place, whereas on the other side many larvae moult which live in moist
places, namely, all the larvae of the Dipt, er a, with many joints to their
antennae, for instance, tho se of the gnats and Tipulce , which distinguish
themselves from the preceding by the possession of a distinct head. The

* Introduction, vol. iii. Nouv. Diet, d Hist. Nat. vol. vi. p. 289; vol.xx. p. 372.

•f Lemon’s d’Anat. Comp. vol. ii. p. 547.

+ Kirby and Spence, vol. i. Lyonet, in Lesser Theologie des Insectes, vol. i. p. 167 *).

432

PHYSIOLOGY.

reason, therefore, why these larvae do not moult cannot lie exclusively
in their damp place of abode ; nor that their existence as maggots is
but of short duration, as, for example, in the common flesh fly from
eight to ten days, but it must be found in other conditions of their organ-
isation which have not yet been discovered. Besides, this phenomenon
also proves that the development of insects of different orders, and even
of the different families of the same order, can take place in a different
manner, and that, therefore, the assertion that the intestine also moults
in some orders, whereas in others it does not, is not so wholly gratuitous;
but we will nevertheless not decide, having made no observations upon
the subject. The determination in another instance is just as difficult,
and in which also the observations of several naturalists stand in direct
contradiction : this is the case in the maggot of the bee. This, accord-
ing to Reaumur and Huber’s observations *, like all the apode larvae
of the Hymenoptera , consequently in by far the majority, does not
moult, but merely gradually grow larger. Whereas Swammerdamm
says expressly that he has observed the moulting of the larva of the
bee f, and that he has likewise found the inner tunic of the intestinal
canal in the caecum behind the stomach of the maggot of the hornet J.
However the case may be, we prefer adopting the first opinion, as all
these larvae exhibit a very great conformity with those of the Diptera,
which certainly do not moult. This conformity refers not merely to
the larva, but likewise considerably to its mode of life, in as far namely
as that the larva of the (Estri , as well as the maggots of the pupa-
phaga, are true internal feeders. But they in so far differ from each
other that the hymenopterous larva casts its skin when it becomes a
pupa ; the larvae of these Diptera , however, change into pupa within
their larva skin. In Stratiomys , indeed, the shape of the larva remains
unaltered, and it was thence that Knoch considered this larva an
annulate worm, in which the larva of the Stratiomys lived as a para-
site I) : in the rest, however, the soft skin of the larva shrinks up into
an egg-shaped, hard, annulated case, in which the pupa is concealed,
with its free and visible limbs. The other Diptera, which moult as
larvae, cast their larva skin before changing into the pupa state ; this
is the case, for instance, in the larvae of the gnats, of the Asilica , Xylo-
pkagi, and many others.

* Kirby and Spence, vol. iii. d* Biblia Naturae, p. 163, a. lb. p. 133, a.

|| Neue Beiträge zur Insektengeschichte, PI. I.

THE METAMORPHOSIS.

433

§ 255.

The changes which take place within the larva during the several
moultings are unimportant. But formerly, where we spoke of the
changes which the intestinal canal and the sexual organs undergo
during the metamorphosis (§ 114 and 143), and which we have since
recently referred to, we noticed that the changes of these organs com-
mence only during the pupa state, and that consequently the cater-
pillar retains the same form of the intestinal canal and the same figure
of the sexual germs, and that both merely increase with its growth, in
compass and in the structure of their tunic. But, upon the larva pass-
ing into the pupa state, a change of the internal organs takes place, as
well as of the external figure. These changes we have indicated at the
above place, but those undergone by the larva we explained earlier
(§ 60) ; it, therefore, merely remains for us to make a few observations
upon the character of these transformations.

With respect to form, by it the law laid down by Von Bär, of a
progression from a general to a particular figure during development,
receives full confirmation. The intestine of the larva is simple, broad,
generally straight, and without many convolutions ; its divisions are not
strongly marked, but pass gradually into each other. During the pupa
state, however, it transforms itself to a longer, much convoluted tube,
separated into several divisions, which now exhibit a distinct difference
of texture; and indeed new organs are added of which there was
formerly no trace, namely, the proventri cuius in the Carahodea , the
sucking bladder and caecum in the Lepidoptera, the villi in the ilium
of the flesh eaters, &c. In the flies, in which indeed the intestine upon
the whole shortens, each individual division, however, and particularly
the ilium, acquires a more determinate form and a more compact struc-
ture ; the sucking stomach more distinctly separates itself, its orifice
lengthens, as also does the oesophagus. In the sexual organs there is
a more distinct difference of structure : parts which previously had a
great resemblance to each other, namely, the testes and ovaria, from
day to day increase in dissimilitude ; and other organs, of which before
there was no indication, gradually form themselves from simple pro-
cesses to long convoluted canals ; lastly, the pupa itself exhibits a vast
discrepancy of form. The larva was a worm composed of equally large
rings ; the pupa, on the contrary, possesses the entire form of the sub-
sequent insect, and differs, therefore, with respect to the forms of its
rings chiefly by the difference of size found between several, namely,

F F

434

PHYSIOLOGY.

those of the thorax and abdomen. This dissimilarity is founded upon
the more determinate figure divaricating more from the general one
which the three segments of the thorax have adopted, a dissimilarity
found to exist not only between them and the segments of the abdomen
but also between them individually.

With respect to the second, the histological and morphological sepa-
ration, the first we have already superficially touched upon. The
tunics of the intestine do not indeed become uniformly more compact
and firmer by the metamorphosis, but in general only in those cases in
which the perfect insect ftakes the same food as the larva, namely, in
the Carnivora. In the Lepidoptera the increased development in-
creases the necessity of better and more delicate nutriment, conse-
quently the butterfly does not require so compact an intestinal tunic as
the caterpillar. The latter has to elaborate and extract the entire sub-
stance of the plant, the former merely feeds upon the most delicate
juices of flowers, namely, their honey. The thick fleshy proventriculus,
armed with horny teeth and plates, most perfectly exhibits the histolo-
gical separation. From the thin membranous cardia of the stomach of
the larva during the short pupa state this powerful and muscular organ
has been produced; from this same thin tunic processes have arisen,
and thus its cavity has distended upon all sides. But in conjunction
with this the general cavity of the ilium decreases, the muscular fibres
contract, and form a compact firmer membrane than that of the stomach
of the larva. And lastly, the morphological separation is even more
decided ; similar rings transform themselves into the most dissimilar
divisions of the body, and in these divisions large muscles grow from
small beginnings, new organs of motion are also associated during the
pupa state, and the old ones become lengthened generally as well as
in their several joints, and, indeed, what was formerly a single joint
becomes divided into from four to five, namely, the tarsus ; or an organ
which consisted of three or four joints now exhibits ten, twenty, and
sometimes as many as fifty. Eyes even, the most important of all the
organs of the senses, originate ; and at a place where previously the
situation of the head was indicated, merely by the orifice of the mouth,
an entire head is formed with all its requisite organs.

§ 256.

The preceding paragraph shows us that the character of the meta-
morphosis of insects is found to be now restricted to its progress

THE METAMORPHOSIS.

435

from a, in every respect, general form to one more particular and deter-
minate. This character displays itself most distinctly in the perfect
insect in the separation of the entire body into three particular divi-
sions, each of which comprises its peculiar organs. It likewise stands
in the closest connexion with the general ideas of development, and of
the higher perfection of organic natural bodies, in as far as by this
structure of the body the individual organs are more distinctly separated
from each other, and each has acquired its determinate situation and a
more artificial composition. The head is the bearer of the organs of
the senses,' the thorax of those of motion, and in the abdomen the
organs of vegetation are placed. That portion of the body, conse-
quently, which in the series of Gastrozoa predominated has become in
the insect if not the smallest yet the most simple and least developed,
whereas that in which all the organs are situated that characterise the
Arthrozoa, which are the organs of motion, namely, the thorax, is, with
respect to its composition and development, the most perfect. But we
have above seen (§ 158) that the organs of motion fall into active and
passive. But this separation is first found distinctly expressed in the
Arthrozoa. We certainly find the active ones or muscles universally
among the Gastrozoa, and also indications of the passive ones are found
in the internal bony parts and partial skeleton ; but a perfect skeleton
of hard parts to which the muscles can be attached is first found in the
higher Arthrozoa, namely, the Crustacea and Insecta , and which
presents itself as an external ossified or horny integument. The most
simple form of this external integument is the ring, all particularities
and individual divarications have consequently proceeded from the
annular form, and must, therefore, admit of being referred back again
to it. The first change, however, which the ring in the progress of deve-
lopment suffers is, that it separates into a superior and inferior half ;
thus are formed the rings or segments of the abdomen, as well as of
many larvae and caterpillars. Whence the lower half thickens in its
centre, and from this spot sends processes inwardly, which also occa-
sionally form into a ring, and thus a smaller ring is inclosed within
the larger one, but both of which touch at one spot, namely, where a
half diameter drawn from the centre touches the circumference. This
inner ring, or the processes which indicate it, receive the nervous cord
within it, whereas all the other organs are encompassed by the larger
external ring. Thus are formed the most perfect segments, namely,
those of the thorax.

f f 2

436

PHYSIOLOGY.

If we compare this structure of the parts of the skeleton with those
found in the vertebrata we discover a not unimportant uniformity in their
fundamental composition. That point namely from which the arch of
both rings proceeds is analogous to the body of the vertebra ; the bow
of the smaller ring presents itself as the foramen medulläre, and that of
the larger ring those moveable processes which hang attached to the
vertebrae, and which are called ribs ; the superior and generally smaller
half ring, lastly, which unites the two arches of the lower half ring to a
whole ring, represents the sternum placed between the ends of the
ribs. Hence, thus we obtain as the fundamental form of the skeleton
of the insect the vertebrae with their radiations, just the same as these
bones form the foundation of the trunk and head-bones of the vertebrata.
The difference between both is found only that in the vertebrata the
radiations of the vertebrae take an opposite direction, whereas in insects
they project on one side only. Besides, this view, which appears to
contain so much truth as not to require a proof in detail, is by no
means new, but has been advanced by several comparative anatomists,
namely, Geoffroy St. Hilaire *, Robineau Desvoidy +, and more
recently by Carus J. We need, therefore, merely refer to the labours
of these learned men, particularly to the last, and those who shall
consider this comparison an absurdity, we draw their attention to his
detailed representation ; it here suffices to have found the result in
a simple development.

§ 257.

But that the vertebrae here lie upon the surface, whereas in the
Osteozou they are encompassed by soft parts, is grounded upon the entire
formative type of the Arthrozoa, which is no other than that the
skeleton in them is always external, whereas in the Osteozoa it has
become internal. But why this is so ordained by nature we can only
answer when we shall have seen why nature has produced Gastro -,
Arthro -, and Osteozoa, and to answer this would be stepping beyond
those limits within which human investigation is restricted, especially
in its inquiry into final causes ; consequently a miscalculation of its
capacity. But one thing strikes us with astonishment, namely, that in

* Annales des Sciences Physic. Part iv. 1820, p. 96 — 133., whence translated in
Meckel’s deutschen Archiv für die Physiologie, tom. vi. p. 59.

f Recherches sur l’Organisation vertebrale des Crustaces, &c. Paris, 1828. 8vo.

+ Yon den Urtheilendes Knochen und Schalengerüstes. Leipz. 1830. Folio, with plates.

THE METAMORPHOSIS.

437

the Arthrozoa the vertebrae lie upon the ventral side, and in the Osteozoa
upon the dorsal. This arises from the situation of the nervous cord ;
if this lie upon the ventral side it then attracts the vertebrae to it, for
it is the earlier, they being formed around it. The nervous system in
general, as well as every individual nerve, seeks the best protected
parts, therefore, in the Gastrozoa, as well as in the Arthrozoa, its main
stem lies at the ventral surface, that it may conceal itself beneath the
other organs. If, then, the ganglionic ventral cord of the Arthrozoa be
analogous to the spinal cord, or as others prefer considering it, to the
dorsal ganglionic chain lying contiguous to the vertebrae, which may be
doubted since the discovery of a distinct nervus sympathicus proceeding
directly from the brain ; then the encompassing parts of the skeleton
will necessarily be analogous to those parts of the skeleton of the ver-
tebrata, which inclose that cord. But we prefer considering the ventral
cord of the Arthrozoa as the true spinal cord, from its passing within
the canal formed by the horny skeleton, and not contiguously, as would
necessarily be the case upon the adoption of its identity with the dorsal
ganglionic chain. According to this representation, therefore, insects
run with their back turned forwards, or rather underwards, and what
is called back in them is the true ventral side. This idea has been
long since suggested, and was immediately, like everything that diverges
from common views, strongly disputed ; but the proofs cited in opposi-
tion do not appear tenable, as will be evinced by what follows in sup-
port of our opinion.

The situation of the intestines perfectly confirms our view. That
organ which lies most approximate to the vertebral column of the ver-
tebrata is, with the exception of the vessels which are deficient in
insects, the oesophagus and the intestinal canal ; even so in insects, it
lies immediately over the nervous cord, directly upon the inner horny
arch when it is closed, or still between its branches. In the vertebrata
next to the intestinal canal proceeding from the back towards the belly
we find the lungs and the heart in the thorax, in the ventral cavity the
intestine touches the ventral surface, in the pelvis the sexual organs
namely, the gravid uterus, lie in front of it. We find exactly the same
arrangement in insects : the lungs are omitted, as they are universally
distributed; in the thorax proceeding from the back towards the breast
we find the heart with its large vessels. In the ventral cavity, whither
the heart also extends, it is likewise placed externally, and indeed the
return of the aorta to the back is indicated in the two main currents

438

PHYSIOLOGY.

passing from the head and proceeding laterally, inclining downwards.
Thus also in insects the motion of the blood first proceeds forwards and
upwards, and then backwards and downwards. The sexual organs,
lastly, lie in front of the intestinal canal, therefore above, immediately
beneath the heart. This situation is shown above in the ovaries ; in
their rudiments also in the caterpillar it was remarked that they lie
above the intestinal canal. The orifice only of the sexual organs differs,
as in insects it lies beneath the anus, whereas, according to analogy, it
should lie above. Nature appears to have pursued a determinate object
in this situation, which agrees with that found in fishes, but which
could not be subjected to the twisting of the insect body; but what
this object is remains undiscoverable. This only is evident, that the
genitalia in insects lie as much in front of the intestinal canal, calcu-
lating from the spinal cord, as in the mammalia and other animals. A
second objection, besides that of the altered situation of the sexual
aperture, which could be made to this twisting of the insect’s body,
might be deduced from the situation of the mouth, which does not lie
laterally with respect to the spinal cord, but upon it, like the former.
But the twisting of the anterior half of the head occasions this, and
that such a twisting is actually the case is proved by the co-relative
situation of the cerebrum and cerebellum, both of which, in fact, do not
lie upon one side, but upon the opposite sides of the oesophagus, namely,
the cerebrum above, on the true ventral side, the cerebellum beneath,
towards the true back. This wholly irregular relation of the parts can
only be explained by a twisting of the anterior portion of the head.
The organs placed upon that part of the head naturally participate in
it, and thus the mouth came beneath, whereas properly it should lie
above, were it in harmony with the entire structure of the insect. But
how is such a twisting consistent with the simplicity of the case of the
head ? The reply to this question appears difficult, but in fact it is
not so when we consider that the head as well as the body consists of
vertebrae. Their number is regulated by that of the cerebral ganglia ;
in the vertebrata there are three, namely, the cerebellum, the posterior
lobe of the cerebrum, and its anterior lobe. This anterior lobe, the
ganglion of smell, is deficient in insects, as they have no particular
organ of smell, and consequently we find in them only two ganglia,
namely, the ganglion of sight and the cerebellum. Thus their skull is
divided into two vertebral arches. These are also ver*y distinct in the
head Qf the larva ; the posterior one, in which the cerebellum lies, is

THE METAMORPHOSIS.

439

the largest, and consists of the throat as the base, and of the two large
temples which meet at the vortex, as the arch. Between them a
triangular piece lies anteriorly and above, the clypeus, which has the
eyes at its lower angles, and the mandibles at its base ; beneath, the
chin lies next to the throat, which thus closes the second arch indicated
by the clypeus. Both together form the second vertebra ; it enlarges
during the metamorphosis, and thereby pushes back the arch of the
posterior vertebra. The oral organs are attached to it, and it contains
within it, the cerebrum, or the ganglion of the eyes. The clypeus is
the body, or vertebra itself, the branches of which, or arch, bend
downwards to the chin ; the chin itself is the upper plate of the ver-
tebral ring, or part corresponding with the sternum. The mandibles
hang attached as limbs to this vertebra. The eyes also are situated
upon the anterior vertebra, and which indicate posteriorly its limits,
in as much as their horny external surface appear, as it were, introduced
in the free space between the two vertebrae, or rather have separated
them from each other. Thus, therefore, the optic nerve passes just
in the same manner between the two vertebrae, as the nerves of the
spinal cord pass between the arches of the vertebrae. The posterior of
these vertebral arches, namely, that for the cerebellum has, as well as
the thoracic vertebrae, its internal processes, or the second ring, which
corresponds with the true vertebral arches. It, therefore, originates as
a furcate process from the throat, and embraces the cerebellum with its
branches. When these branches unite they form the tentorium, or the
small band which divides the occipital aperture into two halves. But
we do not find anything analogous in the first vertebra ; did it exist, it
would necessarily proceed from the clypeus or the forehead.

§ 258.

The opinion, therefore, that the trunk of the insect is formed upon
the same type as that of the vertebrate animal is thus corroborated :
we have exhibited even the same analogy in the head. The chief
difference of the two organisations, however, consists in the back
in the insect being turned downwards, but in the vertebrate animal
upwards. What Von Bär* cites as a proof in opposition to this
assertion, viz. — that the upper side of insects is the distending side,
the lower the bending side, and that, therefore, as in the vertebrata, the

Entwickelungsgeschichte der Thierc, p. 246.

440

PHYSIOLOGY.

former is more densely covered with hair, and more deeply coloured
than the latter — does not at all suffice ; for, in the first place, in very
many insects, particularly in the beetles, the under side is that which
makes the greatest bow, and, therefore, the distending side, and often, as
in the bees, is the most densely haired, and besides the darker colouring,
as the consequence of a greater effect of light, is no proof in opposi-
tion. This is evinced by the universally brighter colour of the upper
side of the abdomen in the beetles, in which the elytra oppose the
effect of light. What also he cites in opposition from the situation and
posture of the extremities is also inapplicable ; for the extremities pro-
ceed precisely from the same side as they do in the vertebrata, namely,
from the dorsal side. In all the vertebrata the extremities are attached
to particular bones which stand in connexion with the vertebral column.
These bones are, for the anterior extremity, the scapulae, and for
the posterior one the ilium, of the pelvis. We refind these portions
of the skeleton also in the Arthrozoa , at least in the most perfect among
them, namely, the beetles ; but they do not lie superficially attached
to the vertebrae and its arches, but as external cases they are con-
nected with the ring which is formed by the vertebra and its processes,
and necessarily at the spot where they properly belong, namely, between
the vertebra and the sternum. This approximation of the shoulder-
plate to the vertebral column is very distinct in the anterior extremity
of the vertebrata, it descending closely contiguous to the vertebrae ; in
the posterior extremity, however, where the ribs are wanting, it is
even traced, in as far as here the ilium borders immediately upon the
vertebral column, and when the sternum here, the os pubis is wanting,
it presents itself as an arched process, upon the vertebral series of the
pelvis. The same is the case in insects ; here also the ribs are compressed,
and the scapulae take their place. We, therefore, obtain in insects both
a shoulder-blade and a pelval piece ; the first is also the plate, called
by us the scapula, the latter our parapleura, the ischium of Straus,
which, properly, should be called the ilium. The most distinct proof
that these pieces merit their names is the fact that the muscles which
move the thighs, namely, its flexor, thence proceed, and that conse-
quently the femur is attached to these pieces. In the anterior legs it
is the omia which correspond with them in situation and function
Analogous to the dorsal and ventral plates these three plates might
therefore, be called the promium, mesomium, and metomium, whereas
the dorsal plates should now be called pro-, mcso-, and metasternum

THE METAMORPHOSIS.

441

and the ventral plates, pro-, meso-, and metanotum. But why do the
thighs articulate with the vertebras itself? — why not with the shoulder-
blade, as it is present ? These questions could be suggested only by a
superficial observer, with reference to the posterior femur, for upon
the anterior and intermediate pairs the shoulder-blade actually forms a
portion of the articulating socket*. The posterior femur also, or
rather its ball, which is usually called the hip, joins the parapleura
above, and this forms a portion of the articulating socket f. Likewise
in the downward bent margin of the parapleura the small articulating
socket is formed for the round ball of the top of the femur which
revolves in the large hip socket. Lastly, the aperture through which
the muscles of motion pass into the thorax is always found between
the pleura and the sternum, and is partly encompassed by the former
and partly by the latter.

Thus the composition of the insect body and the analogy of its
individual plates with the bones found in the vertebrata, is fully proved,
and we obtain as the result that

The head consists of two vertebrae, the one of which is twisted in
opposition to the other

The thorax consists of three vertebral rings, each of which is sub-
divided into the true vertebra, the shoulder-blades and a sternum.

The abdomen consists of nine vertebrae, each of which again consists
of the true vertebra and its arch, which are either the analogies of
the ribs or frequently merely represent the transverse processes of the
vertebra and the ventral sternum, the horny ventral covering. The
last of these vertebral rings, namely, the anal and sexual vertebra, is
also twisted, so that the vertebra with the anus lies above, and the
ventral plates with the sexual apertures lie beneath. These abdominal
vertebrae have no internal processes ; they retain their original most
simple larva form, and generally present themselves as simple but
more frequently halved rings. In some cases, for instance, in the
locusts, from the lateral parts of the half ring other free moveable half
arches project into the cavity of the abdomen, which both in situation

* See PL IX. No. 2. f. 2., No. 3. f. 5. ; PI. X. No. 1. f. 6., No. 3. f. 5.

+ PI. IX. No. 3. f. 5.

X This composition of the head from two vertebra or rings is confirmed by Ratzeburg’ s
observations upon the development of the larvae of the Hymenoptera. See Darstellung
und Beschreibung der Arzneithiere, vol. ii. p. 175, PL 23, f. 47 — 50 and f. 88 — 91

442

PHYSIOLOGY.

and function perfectly agree with the ribs. But I have never been
able to find a second series of vertebral arches for the nervous cord.

§ 259.

We must now proceed to the comparison and explanation of the
limbs. We have shown above that the wings are no limbs, but gills
(§ 243). For the completion of this uniformity, which is already
exhibited by their structure from two external membranous layers and
the currents of blood distributed between them, we have only to show
that these gills lie precisely where when present the gills are always
found. If we, therefore, commence with the superior groups, we shall
find that in them the branchial apertures lie at the anterior part of the
neck, and, consequently, upon the ventral side. In some amphibia,
namely, the Batrachians, they are found exactly at the same spot.
The same in the fishes. In these they are protected additionally by
means of a bony covering which opens posteriorly and beneath, and
therefore towards the venter. In the Mollusca, the branchiae lie more
or less upon the back, as it is called, but their back is nothing else than
the true belly, from the very same reason, that in them also the main
nervous mass takes its course along the so called ventral disc.

We thus obtain this general law for the situation of the branchiae,
viz. that they are placed laterally, but inclining to the venter, and
thence descend to the venter. The wings have the same position; they
originate between the scapula and sternum, consequently upon the
external side of the body, and thence descend to the ventral side. In
those insects furnished with gills, they also lie at the same part ; they
always originate at the side where the main stems of the tracheae lie,
and thence rise upwards, either wholly so or partially inclining back-
wards, as in the larvae of the Ephemera and Vhryganece. As long as
the insect dwells in the water, its rudimental wings are true water gills,
but so soon as it has quitted the water, they transform themselves into
air gills, for in both cases fluids circulate in their vessels, which,
doubtlessly, receive oxygen from the air. The beetles exhibit the most
perfect conformity, for in the entire hardening of their body the wings
also have become horny, and now supplant the place of gill covers.
The Orthoptera approximate to this structure by their pergamentaceous
superior wings, but many Hemiptera approach still closer, for in them
half the wing is horny. Thence we must remove the wings from the
category of limbs, they being merely gills which are occasionally moved

THE METAMORPHOSIS.

443

in the air, just as the gills are incessantly moved in the water ; the
insect, therefore, uses them for flight, as the former are used by larvae
for swimming. The endeavour of some naturalists to see arms in the
wings, and to indicate in their ribs the arm-bones with their joints and
inflexions, cannot therefore be justified. The wings present me with
no other resemblance to limbs than that they move and assist the pro-
gression of the creature. If this be the sole character of the arm or of
the leg, I will then admit that they are either arms or legs, but, other-
wise, certainly not.

§ 260

But there is less doubt of the legs being analogous to the extremities ;
indeed, they have always been considered as such, and the entire leg
as well as its individual joints have been thence named. The first
question that suggests itself is — Are the legs forms truly analogous to
the arms and legs of the vertebrata? To this we may safely reply in
the affirmative, for these limbs are similarly situated, and often consist
of just as many, and sometimes, indeed, of more divisions. The similarity
of situation is shown above, where we have treated of the scapulae of
the vertebra representing the true scapulae ; we have there seen that
the legs hang attached to a distinct plate between the vertebra and the
sternum, which corresponds with the scapula or the ilium of the pelvis,
and that it is from this plate that the majority of muscles come, positive
facts which prove an important analogy.

With respect to the division of the limbs, we always find in insects
at least five but never more than nine joints ; of these, the first and
third, with the smallest second, form a joint articulating upwards ; the
fourth with the third one articulating downwards ; the fifth with the
fourth one again articulating outwards ; the following joints, lastly, sit
where they present themselves upon the fifth, and take a straight
direction, and also participate in its motion, yet the entire foot can
bend downwards and again distend itself. A perfect conformity with
the anterior limbs of the superior animals has been supposed to be
found in these articulations. It has been endeavoured to explain the
first joint, the coxa of entomologists, as the humerus ; the second
smallest, as the separated olecranon, the analogue of the patella ; and
the third, the femur of entomologists, as the antibrachium ; the fourth
joint, the tibia of entomologists, would then be the carpus ; the fifth,
the metacarpus ; and the subsequent ones, the joints of the toes or
phalanges. This explanation becomes absolutely necessary, if the legs

444

PHYSIOLOGY.

of insects be considered the analogues of the anterior limbs ; but I
prefer considering them as the posterior limbs,, and, indeed, because
those are the least perfect, not only in structure, but also in function.
Where, therefore, true limbs first present themselves, there must they
be considered as the inferior ones or legs. Both, however, the arm and
the leg differ from each other in the angles of their joints, being opposed
so that the angle which in the anterior extremities open outwards, on
the posterior ones open posteriorly. But these differences are not found
in the extremities of insects ; the anterior ones are merely distinguished
from the posterior ones by their situation, for their corresponding angles
all open upon one side. Hence, therefore, the hip is not the thigh, but
the hip, and the trochanter and femur form conjunctively the thigh.
The hip is the head of the femur, the trochanter its neck, and the femur
its tubular body. This division of the femur into three parts is occa-
sioned by the feet being in insects so placed, that they proceed as it
were from the lower end, and direct themselves upwards, in which
direction they possess considerable power of motion, which was only to
be attained by this mode of articulation. If in solitary cases more
mobility is required, the trochanter must be divided into several pieces,
and this is exemplified in the genus Pimpla (§ 83. 2.). If, however,
it be the elbow or olecranon, in this instance we must adopt the exist-
ence of two successive patellae, for which there is no analogy ; but if a
division of the thigh into three parts may be imagined, it is still more
possible to conceive its subdivision into four. If now the coxa,
trochanter, and femur be the subdivided superior thigh ( femur ), the
tibia must necessarily be the lower thigh (tibia). The angles of both
joints fully harmonise with this view, in as far as they always open
either posteriorly or inferiorly. The first large joint of the tarsus then
indicates the metatarsus, as the basal bones are wanting, and the
following are then the phalanges. They vary considerably in number;
sometimes they are entirely wanting, but never more than four exist.

If after this explanation, which must still appear forced, from the
deficiency of the basal bones of the foot, we look around us for an
analogy in the higher animals, we find the most perfect conformity in
the structure of the foot in birds. In these, also, the basal bones of
the foot are deficient, and in them, also, there is a variation in the
number (from one to four) of their phalanges. This variation is found
in every individual bird, in as far as each of its four toes, commencing
inwardly, increase one joint, so that the innermost, generally the

THE METAMORPHOSIS.

445

posterior one, has one joint, and the three anterior ones, in regular
rotation, two, three, and four joints. In insects, on the contrary, this
variation is distributed throughout the whole order, so that their one
toe of each foot exhibits either one, two, three, or four joints : it is more
unusual for some toes to have three and others four joints, as is the
case among the beetles, for instance, in the Heteromera.

It is hoped that no one, after this comparative view, will take
objection to the explanation of the leg joints ; he will but find a con-
formity of insects with birds, to which, in the course of our treatise,
we have frequently referred, and he must therefore be necessarily
convinced of the correctness of what we have advanced. Birds are in
every respect concentrated insects, and insects birds deprived of their
internal skeleton.

FOURTH CHAPTER.

OF MUSCULAR MOTION.

§261.

The collective motions of animals are produced by a distinct system
of organs, which we call muscles. With respect to the structure and
arrangement of these organs in insects, we have already stated all that
was requisite in the third chapter of the preceding division ; we conse-
quently consider as known both the structure of the entire apparatus
of motion as also of its individual parts, and proceed at once to the
consideration of their functions.

We obtain as the first and chief difference in motions their subdivision
into voluntary and spontaneous.

Under the spontaneous motions we consider all those which are not
subject to the influence of the will, and which take place in the insect,
from the commencement of its life to its death, precisely in the same
manner, and which can never be wholly or for any long period inter-
rupted, so long as life is to proceed uninterruptedly. We know, from
what has preceded, that all these organs are encompassed by a peculiar

446

PHYSIOLOGY.

muscular layer, which, by means of compression and distension, produce
a certain change in the compass of the vegetative organs, which partly
contracts them and partly allows them to relapse to their former com-
pass, and that it is only in consequence of this motion that the functions
of every individual part and organ can proceed uninterruptedly. These
motions are especially visible in the several parts of the nutritive
system, where they present themselves as the peristaltic motion of the
intestinal canal, as the respiratory motion of the tracheae, and, lastly,
as the pulsations of the heart. All these motions have been described
sufficiently in detail in a former chapter, where we have spoken of the
functions of the nutrimental system, and where we discerned in them
the true cause of the entire process of nutrition, which commences with
the reception of the food. The motions of the sexual organs are less
apparent, as they become visible only at certain periods. Yet in the
male sex there appears to be, from the moment of puberty, an undis-
turbed production of semen. This semen, by means of a motion not
dissimilar to the peristaltic motion of the intestine, arrives in the vesica
seminalis, whence it passes during copulation into the female organs.
After this act the activity of the female organs commences, which
exhibits itself as a peristaltic motion, both in the egg-tube and in the
oviduct, and where it terminates in the production of the collective
egg germs.

Upon surveying the common expression of all these motions, we
recognise nothing further in them than a spontaneous re-action on the
part of the organism to external irritation at least, external in reference
to the organ which is moved. This irritation consists in the food, for
the intestinal canal, the atmospheric air for the tracheae, the blood
for the heart, the semen secreted by the testes for the male organs,
and for the female organs the male semen also which is conveyed into
them.

§ 262.

The stimulus, however, which determines the action of the voluntary
muscles is the will only of the creature ; the insect has but to will, and
in the same moment its legs are in motion, and it flaps its wings and
hastens away. The common property of both, therefore, consists in
their requiring a medium of irritation, the differences we find in the
phenomena are that this excitement for the involuntary muscles is
physical and corporeal, and that for the voluntary is spiritual. Both

THE METAMORPHOSIS.

447

descriptions of muscles, however, may be affected in the same manner
by one and the same excitement, for electricity effects both a contraction
of the heart and the same phenomena in the muscles of the limbs.

The first thing we perceive in the activity of any determinate muscle
is a contraction of itself. By means of this contraction its compass
enlarges, its texture feels more compact and firmer, and the entire
muscle is in a state of excitement. How this excitement is produced
we know not, but thus much is ascertained, that the nerves exercise
great influence upon the motions of the muscles. But the nature of
this influence we must leave undetermined whether, as some physiolo-
gists suppose, generation produces the necessary power for acting upon
the muscles, or whether, with others, it be to be considered as merely
the conductor of the excitement from its point of production to the
muscle. We are most fully convinced of the importance of the influence
which the nerves exercise upon the motion of the muscles when galvanic
electricity is applied to a nerve and a muscle standing in connexion
with it, or upon its application to the former alone. Alexander von
Humboldt, whose great genius first announced itself in a surprising
manner in the illustration of this difficult and then insufficiently-
laboured field of physiology, has supplied us with some interesting
observations, even in reference to insects *. He saw animated con-
tractions in the limbs when the nerves passing to them w7ere touched
by the poles of a voltaic pile, re-actions which continued for a space of
twenty minutes, and which admitted of being prolonged three times
that space upon the nerves being artificially prepared with alkalis and
oxidised muriatic acid. He also observed in the thigh of a Blatta
oriental is, touched with gold and zinc, from two to three successive
shocks ; indeed “ the thigh raised itself up, and held itself some
seconds trembling in the air.” He further remarks : “ Upon galvanising
the spinal marrow of a Blatta orientalis with silver and well-burnt
carbon, I observed its posterior portion move to and fro and press with
its feet.” Even in the body of a Vespa crabro, the head of which
had been cut off fourteen hours before, the same admirable observer saw
the limbs tremble upon the application of the metallic stimulus.

This trembling of the limbs after the effect of galvanic electricity
speaks also in favour of an oscillation of the muscular fibres in insects as
well as in the superior animals. This oscillation was formerly denied

* lieber die gereizte Muskel-und Nervenfaseir. Berlin, 1797. 8vo. vol. 1, p. 273.

448

PHYSIOLOGY.

in insects, and its deficiency explained from the imperfection of their
nervous system. But the muscular and nervous system of insects is as
perfect as that of the Cephalopoda, and there can be no objection to
admit it in the former, since it has been proved to exist in the latter *.
We undertand in this oscillation an undulating motion of the fibres,
which is seen together with the contraction, and which, for instance,
exhibits itself in partially pressed muscles, as a trembling motion which
frequently seizes the entire limb. The incessant vibrating motion in
many parts of the body of many insects, for instance, the motion of the
antennae in the Ichneumonodea, the trembling of the wings in repose,
the palpitation of the extremities of the feet in Chironomus , &c.,
appear to be less the result of voluntary muscular motion than of the
oscillation peculiar to all perfect muscular substance.

§ 263.

This muscular activity is therefore the foundation of all the motions
exercised by insects. These motions may be referred to four principal
kinds, namely, walking, jumping, swimming, and flying. But few
insects are restricted to the first and most simple of these motions, the
majority possess the power of flight in addition ; some can only walk
and leap, as the flea ; some can walk, leap, and fly, as the grasshopper;
many can walk, fly, and swim ; whereas there are none which possess
the power of swimming and flying in conjunction. Many larvae can
only walk and swim, others creep and swim ; no perfect insect, how-
ever, possesses the last mode of motion exclusively.

If we now investigate the first, most simple, and most universally
distributed of these modes of progression, walking, this also may be
subdivided into several kinds, from the structure of the motive appa-
ratus. The first, and most simple, which is the progression of maggots,
without the help of feet, and is properly merely an advance upon the
ventral surface, is a sort of slow creeping. The maggot thus progresses
by means of the longitudinal contraction of its body, whereby the
distended and, as it were, swollen head is pushed onwards, this then
affixes itself by means of the lower and strongly projecting ventral
surface of the first abdominal segment, which appears to act something
like a sucking cup, and then draws the body as far as possible after it.
The posterior extremity, which in general is furnished with distinctly

K. A. Rudolphi Grundrisz der Physiologie, vol. ii. part i. p. 290, 294.

OF MUSCULAR MOTION.

449

projecting pedal warts, then likewise attaches itself, and thus the body-
pushes itself forward by gradual contraction of all the segments, which
begins behind. The alternating attachment of the anterior and pos-
terior ends is repeated as long as the maggot is in motion. We find
this mode of progression in all the apodal larvae of the Diptera , and
they accomplish it better upon uneven, rough surfaces ; upon a smooth
surface their progress is imperfect, and then frequently the short pedal
warts refuse their office. Some of the larvae of the Diptera , whose
pedal warts, as well as occasionally the entire body, are covered with
short horny spines or bristles, can perform this creeping motion more
quickly and securely, but the mechanism is just the same. As an
instance of the first kind of creeping we may cite the larva of the blue-
flesli fly ( Musca vomiloria, PI. I. f. 25.) ; and, as the representative of
the second, the rat-tailed fly, the larva of Eristalis tenax (PI. I. f. 32.).

The motion of larvae with thoracic feet and one or two pairs of anal
prolegs (the geometer caterpillars, PI. I. f. 35.) next follows. In them
the step-like advance is more distinctly performed by means of the at-
tachment of the first and last abdominal segments. The whole of the
middle of the body bows itself into an acute arch, so that thereby the
anterior and posterior feet are brought closely together; the posterior
feet then remain affixed, but the anterior ones are so far pushed for-
ward with the extended body until it lies parallel to the surface; they
then also affix themselves, and draw the posterior ones after them by
the arching of the body.

The motion of the caterpillars furnished with thoracic, ventral, and
anal legs is indeed the same, but it so far differs that all the segments
possessing legs participate in the attachment. This attachment is now
no longer from behind forwards, but, after the pairs of thoracic feet have
advanced and affixed themselves, the ventral feet follow in succession,
until the last pair, or the anal prolegs, move forward whilst the ventral
feet still further advance. Thus the whole body is producing a con-
stant undulating motion as the raising and attachment of the conse-
cutive series advance in regular progression.

Lastly, the walk of six-legged larvae very much resembles that of the
perfect insect. In both, one of the anterior legs, generally the right
one, makes a step which is followed almost simultaneously by the left
anterior leg and right intermediate one. Whilst now the right anterior
leg is making another step the left intermediate and right posterior
ones make the same movement, and thus support it ; whereas the left

G G

450

PHYSIOLOGY.

posterior leg makes a simultaneous movement with the left anterior and
right intermediate. This contemporaneous motion of the several legs
does not generally take place so exactly synchronally, but rapidly in
succession, so that all the legs of each side are occupied in a constantly
progressive advance. The anterior and posterior legs appear to take the
greatest share in this advance, and the intermediate ones seem only
to support them. Thus, the anterior and posterior legs of one side and
the intermediate of the opposite side appear to progress together. But
this successive motion is distinctly visible only in insects walking
slowly, but, when running, the interval of time is so short between the
movements of each individually that the contemporaneous motion of
different legs is scarcely perceptible, and we can only discern an alter-
nating advance and remaining behind of the two legs of one pair as
well as the rapidly successive advancing motion of all the legs of one
side.

In this motion of the entire leg every joint, each in its particular
manner, participates, so that the hips revolve upon their axis, the femur
approaches to it, and the angle between the femur and tibia becomes
more acute when the leg bends, whereas all lie more in a line when the
leg is extended. The anterior legs, however, bend in an opposite direc-
tion to the rest, for they are extended when they advance ; the others,
on the contrary, upon the same movement are bent, whereas, if the
posterior ones extend themselves, the anterior pair must necessarily
bend. Hence arises the differences in the insertion of the muscles in
the hips. The chief object in the anterior pair, namely, is the advanc-
ing motion and clinging, but in the posterior pair it is a pushing
forward, which is attained by means of extension. Thence the anterior
and posterior legs have more extensors than flexors (at least in Melo-
lontha , see § 179) •, whereas the intermediate participate chiefly in the
advancing motion of the anterior legs^ of the opposite side, and have
consequently more flexors than extensors : an advance forwards is espe-
cially prescribed to them, we therefore find their flexile apparatus more
developed than the extensional.

§ 264.

Leaping, also, is in general effected by means of the legs ; but, as
exceptions, we find peculiar organs and apparatus adapted for the
purpose.

When the legs leap it is again the posterior ones which produce the

OF MUSCULAR MOTION.

451

chief motion, and they are then therefore altogether larger, and also
some of their joints are more fully developed. This development chiefly
affects the thigh ; it is not only longer than in the anterior legs but also
much thicker, particularly at its lower end when it is very long, or in
the middle when it but little exceeds the rest in length. In the first
case it is obclavate, and in the last it is either ovate or conical. When,
therefore, a leap is to be made, the posterior leg bends at its knee joint
as much as possible; usually the femur and tibia then touch each other.
The tarsus is also so much bent back that its superior surface touches
the tibia, but the entire femur is so depressed that its axis is parallel
to the surface upon which the insect rests. In this position, with its
anterior legs somewhat withdrawn, the insect stops for some seconds,
as it were to collect itself, when it distends all and chiefly the posterior
legs with considerable force and rapidity, and by means of which it
throws itself from the surface. We therefore perceive that it is chiefly
the extensors which produce the leap ; they are consequently through-
out the whole posterior leg, and particularly the thigh, the strongest
and largest, whence it is also that the greater convexity of the thigh
is always above, and not beneath.

The line described by the insect in its leap, if, for instance, when
winged it should not expand its wings, and by their action supporting
the leap continue it by flight, is that of all projectiles, namely, para-
bolic, which is explained by the gradually increasing gravity of the body,
and in consequence its decreasing power of flight. But the extent of
the leap depends partly upon the force with which it is made and
partly upon the size of the body, but particularly upon the latter, so
that we may consider as a law that the larger the body of the leaping
insect the less is the extent of its leap, and the flatter is the parabolic-
line. Both, however, depend upon the flexure and correlative position
of the femur and tibia, so that the smaller the bend the shorter and
flatter is the leap. Thus every insect regulates both the direction and
height of its leap by the position of its feet and the force of their
extension.

The power of leaping in insects, from the lightness of their bodies,
and the relative strength and size of their muscles in general, is consi-
derable, and doubtlessly greater than in any other animals. No
mammal can leap proportionately so high and far as the flea, which of
all insects possesses this power most strongly developed, for in one leap
it will spring a height exceeding two hundred times the length of its

g g 2

452

PHYSIOLOGY.

body. The following genera of minute Coleoptern , Hymencptcra , and
Hemiptera class themselves with it in this power of leaping, and wre
place them in the order of the progressive decrease of the function ; for
instance, Haltica, Orcliestes, Eupelmus, Chalets, and other Plero-
malidce, Jassus, Aphrophora, Chermes, Livia , &c. The larger Cicada,
grasshoppers, and locusts do not leap so well. We also find a few
minute Diptera possessing this power ; for instance, many species of
the genera Ceratopagon and Tacky dromia, in the first the males espe-
cially, but in general their activity is but small, which is probably
occasioned by their softer integuments, whence the contraction of the
muscles is much less, but which also may be partly ascribed to the less
perfect development of the muscles themselves.

The two families of insects in which ,we detect peculiar organs for
leaping are the Elaters and the spring-tails ( Podura , Smynthurus, &c.)

In Elater, the articulation of the pro- and meso-thorax gives them
the power of leaping, but it can only be accomplished when the insect
lies upon its back, whence, should it by any accident be placed in this
position, it could not readily recover itself, owing to its short legs and
flat back ; nature has therefore supplied it with assistance in the mode
of the articulation of the two thoracic segments. For this purpose the
mesonotum and mesosternum are prolonged into a projecting tubular
process, which is fitted to a cavity in the pronotum and prosternum ;
upon this process we find in the middle of the anterior margin of the
mesonotum a hook-sliaped joint, bent upwards, adapted to a cavity in
the posterior margin of the pronotum. At the base, close to this hook,
there are two smooth flat articulations, which likewise fit two flat
cavities in the pronotum. The mesosternum has, on the contrary,
exactly in its centre, a deep funnel-shaped groove, into which a conical
process of the prosternum fits ; upon the anterior margin, close to this
large groove, there are two smaller cavities for the reception of two flat
processes, which lie at the base, close to the conical process of the pro-
sternum. Their connexion is effected by a tubular membrane, which
passes from one segment to the other. If now the insect lie upon its
back, by means of the muscles which connect the two dorsal plates
together it raises its body upwards, so that the pronotum, moving upon
the processes of the mesonotum, bends back upon the dorsal surface of
the body. It now suddenly contracts with all its force the connecting
muscles of the two thoracic segments, as well as the others which run
down from the mesonotum to the prosternum, and it thereby strikes

OF MUSCULAR MOTION.

453

violently with the somewhat raised margin of the pronotum, and the base
of the elytra against the ground, which throws it upwards, yet, as this
blow does not proceed from the centre of the body, but its anterior
portion, this part receives the greater impetus, in consequence of which
the body turns over in the air, and it consequently falls with its ventral
surface to the ground. It retains itself in this position by the sudden
clinging of its legs, and so prevents the effects the concussion would
otherwise have of throwing it up again. The dagger-shaped process of
the prosternum, which tits into the funnel-shaped groove of the meso-
sternum, has no other purpose in this motion than to regulate and pre-
serve the direction of the prothorax during the contraction, without
participating in the least in the blow.

In the spring- tails a furcafe process originates at the ventral plate
of the penultimate and ante-penultimate abdominal segments, which in
repose lies extended towards the head along the belly, and reaches to
about the posterior legs. By the insect striking this process rapidly
and with force against the surface it is enabled frequently to make an
extensive leap. During this leap the fork is directed posteriorly, but
as soon as it again touches the ground it again bends forward. In
Smyjithurus, Lat., De Geer found, besides, a conical process at the
sternum, whence the creature projected two long flexible filaments when
it wished to affix itself*. Probably these filaments also participate in
producing the leap, which is much greater in them than in Podura .

§ 265.

In swimming, insects are assisted either by their legs or other organs,
which, in conjunction with other functions, exercise also that of fins.
Among these organs may be classed the branchial leaves of the larvae
which live in water, of which we have before noticed their incessant
motion backwards and forwards, whereby the larva moves and breathes.
This is however the case only in those larvae which have lateral
branchial leaves ; a portion of the rest, for instance the larvae of the
Agrions, move by the serpentine motion of their abdomen, and the
leaves at their caudal extremity, which act as a rudder. Thus also do
the larvae and pupae of the gnats move. Others, again, swim like the
leech, by a serpentining of the abdomen ; which motion sometimes
describes an undulating line, and sometimes, as in the red larva of

* Mdmoires, tom. vii. p. 20, PI. 111. f. 7, 8.

454

PHYSIOLOGY.

Chironomus plumosus, it is produced by means of a lateral convolution
of the anterior portion of the body, whereby its posterior end strikes
forwards.

But all perfect insects, as well as the larvse of those with an imperfect
metamorphosis, which live in water, swim by means of their legs.
Among the Coleoptera it is the family of Hydrocantharides which
possess this faculty, for example, Hydrophilus, Elophorus, and the
whirl wigs ( Gyrinus ) ; other insects which live in water, as many Cur-
culios , Helodes Phellandrii, Donacia Zosterce , Elmis , Potamophilus,
Parnus , cannot swim, but creep about, clinging to different objects.
In the other orders we find but a single family of the Hemiptera whose
limbs are adapted to swim, namely, the genera Notonecta , Sigara,
Naucoris, and also in an imperfect degree the genus Nepa. They all
are, like the majority of insects, from the quantity of air contained in
their bodies, as well as from the lightness of their constituents, of less
specific gravity than water, and consequently float upon the surface
without any exertion of their own, when they contract their limbs.
The respiration of atmospheric air, to which all these genera are
restricted, is thereby facilitated to them. It is thence also that many
water-beetles cannot quit the surface when they have remained for
some time in the air ; the air then exercises so great an attraction
upon them that their swimming power is not able to counteract it,
and they consequently remain in this condition until they succeed in
overcoming it. This may be observed in any Gyrinus ; it first whirls
itself about upon the surface before it can dive. Other beetles have so
little specific gravity, that even with all their endeavours they cannot
get beneath the water when any accident has removed them from their
places of concealment to the surface. This is the case in many of the
smaller Hydrophili, for instance, in Hydrophilus orbicularis and the
Elophori, These, therefore, never swim, but creep about, clinging to
objects beneath the water ; if they quit their hold they immediately
rise to the surface, and struggle here until they meet with a reed, that
serves them as a ladder to descend by. Even the powerful Hydro-
philus piceus swims very awkwardly, and has great difficulty to
continue beneath the water.

The great Dytici are the best swimmers, namely, Dyticus dispar,
or Rceselii. The whole form of its body is flat compared with its
size, much narrowed anteriorly, and laterally has a sharp edge, which
gradually increases in bulk to where its posterior legs are placed.

OF MUSCULAR MOTION.

455

and then again narrowing by degrees, contributes very considerably to
facilitate its swimming. The legs also, particularly the posterior ones,
are flat, compressed, and either upon one or upon both edges thickly
furnished with long setae or bristles. The first joint of the tarsus has
a very free motion, and can so place itself that either the sharp edge
or broad flat surface of the entire foot is brought forward and opposed
to the pressure of the water. In the first case the motion finds little
resistance, and easily cuts through the water, and in the last the
pressure of the water acts as a resisting medium against the broad flat
surface of the foot, which is increased to about double its width by
means of the Ions; fringes, and thus the beetle is enabled to advance. In
addition to the repulsion which the rowing of the insect occasions we
may also add the pressure exercised by the water itself, occasioned by
the specific gravity of the insect. Were the beetle placed horizontally
in the water it would thereby be raised upwards, but its posture is
not horizontal, its axis forming an acute angle with the surface, and
indeed the head is the deepest situated. By means of this position its
swimming is much facilitated, as the pressure of the water from beneath,
acting against an oblique surface, pushes both sidewards and upwards.
The rowing of the beetle therefore has only to overcome that portion of
the pressure which urges upwards, and then, without further exertion
on its part, the beetle swims forward. If, therefore, it applies more
power than is requisite for its swimming direct, it necessarily descends
obliquely, and we consequently always observe it to dive in this direction,
and never perpendicularly. But its own muscular activity is, however,
the chief cause of its motion in water. This muscular motion is exer-
cised principally by the posterior legs, which bend forwards as far as
possible, when the narrow edge is directed anteriorly. In their dis-
tending motion all the joints bend, but particularly those of the foot,
so that their broad surface is opposed to the pressure of the water ; at
the same time, but probably merely mechanically, by this pressure the
stiff marginal fringe is expanded, so that by lying closely contiguous
it forms as it were the face of the oar which the insect uses in its
posterior legs. The violent extension of the leg to where it meets its
opponent of the opposite side, behind the body, then propels it, and a
repeated rowing continues the commenced motion.

The genera Nolonecta, Naucoris, and Sigara swim in the same
manner, but with this essential difference, that in them the ventral
surface is directed upwards, and the keel-shaped back is directed
downwards.

456

PHYSIOLOGY.

§ 266.

Flight, the last of the voluntary motions to be considered by us, is
the most difficult to explain of all, as not only the muscles which are
attached to the organs of flight, but all those found within the thorax,
participate in producing it, and therefore it is not merely the wings
during flight but the entire thorax, by means of the motion according
to its several plates, which are detected as contributing to effect it.
We can consequently distinguish two chief motions which are visible
during the flight of an insect, namely, the individual motion of the
wings themselves, and the contemporaneous motion of the thorax. The
above described respiratory motion of the thorax during flight is iden-
tical with the latter, so that the same motion which effects the in- and
expiration of the air from the thorax produces also the flapping of the
wings.

The motion peculiar to the wings consists in their expansion and
bending backwards ; the expansion is produced by the extensors and
the bending back by the flexors. From § 178 we know that the
extensors are by far the largest of these muscles, and that they vary in
compass according to the varying size of the anterior and posterior
wings. By the contraction of an extensor, therefore, the wing is
expanded, and by the continuance of this contraction it is retained in
this position. In those orders with four membranous wings or coria-
ceous anterior wings we find no difference in the position of the wings
during expansion. The anterior ones lie in front of the posterior ones*
and in one plane with them, sometimes separate and sometimes con-
nected with them by means of a peculiar apparatus. In the beetles,
however, in which the anterior wings are transformed to hard elytra,
their position is quite different. Sometimes these elytra are not at all
expanded during flight, and this is the case in the genus Ceionia and
in the earwig. In other instances the elytra are expanded it is true,
but in a very different direction, namely, perpendicularly upwards ;
whereas the wings are extended horizontally, as we observe in Necro -
phorus , in the genus Histcr, and in many Staphylmi. In many other
beetles, lastly, they lie in the same direction with the wings, yet not in
general upon the same plane, but a little higher. In all these cases,
therefore, the elytra do not participate in the blow of the wing, but
they retain the same position and situation during the whole flight.

The remaining muscles of the thorax, but particularly those of the
two segments upon which the wings are placed, and which above

OF MUSCULAR BIOT I ON.

457

(§ 176) we have called the dorsal-, lateral dorsal-, lateral- and furcate
dorsal-muscles, are those which act in common for producing the respir-
atory and volatile motions, and therefore must be examined here more
closely as to their effects. One of them, the straight dorsal muscle,
which is expanded between the meso- and meta-phragma, acts parallely
to the axis of the body ; it arches by its contraction those plates within
which it lies, and thereby produces the inflexion of the wing. In
insects with connate thoracic segments it is assisted in this function by
the oblique, lateral dorsal muscles, which likewise sit quite alone upon
the dorsal plate and its processes, particularly the metaphragma. By
means of it, therefore, the blow downwards of the wing is produced,
and as it also arches the entire thorax, and likewise also distends it, it
promotes the inspiration of air. In opposition to them the lateral and
furcate dorsal muscles act. By their contraction they approximate the
dorsal plate to the sternum, draw it down to the latter, and thereby
effect the raising of the wing. They also contract the cavity of the
thorax, and thereby promote the expiration of the air. By the alter-
nating contraction of these muscles, opposed in their effects, the flap-
ping of the wing of insects is produced. It is therefore the result of a
distension and contraction of the thorax, in which naturally its lateral
radiations, the wings, must immediately participate ; this is another
reason for considering the wings as mere continuations of the membrane
of the thorax, which, only in consequence of their change of function
occasioned by internal respiration, have received their peculiar extensor
and flexor muscles.]

If after this very general survey of the mode of flight in insects we
look around us for some peculiar divarications of individual orders, we
shall find it expressed, especially in the position of the entire body, as
well as of its individual limbs. With respect, in the first place, to
taking flight, we shall even find some differences in the manner in
which this is executed. Those that likewise possess the power of
leaping, namely, the Grylli and Cicada , do it most readily. They
raise themselves by a leap from the ground so soon as they may be
urged to take flight, then expand their wings already floating in the
air, and proceed in the direction already given by the leap. Yet
are these insects not good and continuous fliers, with the exception of
the migratory locust, but the majority return again to the ground at a
very short distance from their place of starting. With the same ease
do all other flying insects take wing which bear their wings always

458

PHYSIOLOGY.

expanded, for instance, many flies, butterflies, Hymenoptera, and many
Libellulce. In the latter, also, they remain in the same position during
repose that they are found in during flight ; the insect, therefore, does
not require to expand and direct them. Thence arises the facility with
which these creatures raise themselves into the air ; thence, also, as
well as from their lightness of structure and small size, the facility of
their motion in the air, and the long continuance of their flight. Beetles,
and especially the largest ones, have the greatest difficulties to overcome
in taking flight. We observe in them distinctly the great exertion
not only of the muscles of flight, but all the other organs of the body
also labour to support their flight ; and the cockchafer in particular,
which, doubtlessly, every one of our readers has observed in this occu-
pation, gives us a distinct idea of the great labour these little creatures
are obliged to apply to the execution of one of their most ordinary
occupations. We see it at first, as it were conscious of its increasing
labour, slowly raise itself, expand its antennae, and, in the endeavour
to free itself of a burdensome and hindering load, adapt itself to its
purposed course by violent respiratory motions of its abdomen. It has
hardly cast this burden from it, when it forthwith commences with
considerably increased activity its pedestrian journey, seeking for some
elevated spot whence it may commence its aerial expedition ; and if it
do not speedily find one, its anxiety to fly urges it to endeavour from
the plain surface, but this impatience is frequently punished by the
failure of its exertions. But, having reached an elevated spot, it raises
its elytra during the violent backward and forward bending of its head,
then suddenly expands them as well as the wings, and at the same
moment makes its first elevating blow, after having, at the same time,
compressed the whole abdominal cavity by means of the flexible dorsal
integument, and thus driven all the air out of it. Thus, during flight,
respiration takes place only in the thorax, and the abdomen resumes
that function only when the creature alights after its completed course.
But then its first motions are very violent and powerful.

The position of the body during flight in the air in this and other
beetles is not the usual, viz. the horizontal, but inclined obliquely
towards the horizon, in which inclination the head takes the more
elevated, and the anal extremity the lower place. The cause of this
oblique position I think may be found in the preponderance of the
abdomen, particularly during puberty, owing to the turgidity of the
internal genitalia, over the smaller and lighter thorax and head ; at

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459

least in those insects in which no such preponderance of the abdomen
can occur, partly from its smallness, as in the flies, and partly on account
of its thinness and lightness, as in the Libellulce, we observe no such
obliquity during flight : whereas in other insects in which the abdomen
itself is heavier, for instance, in the Bornbi and wasps, we observe a similar
posture, yet its greater weight does not incline the thorax from its hori-
zontal position, but the abdomen alone, which is affixed at one small spot,
hangs down. In other insects, again, in which the very long and also
heavy abdomen forms by far the most considerable part, it is placed in
such a position as not to incline the thorax during flight considerably
from its horizontal position. Among these is found the genus Fcenus ;
which raises, during flight, the abdomen with, in the larger species, its
very long ovipositor, perpendicularly upwards, or even sometimes bends
it forwards, so that the chief pressure is directed towards the centre of
the body. But there requires less strength to advance the thus pressing
abdomen, than if, stretched directly out, it drew the entire body down-
wards, and daily experience can teach us how much more easy it is
to balance a long stick upon the flat hand or the tip of a finger, than
to carry it with an extended arm. Most external organs adapt them-
selves to the same law, for the legs are in general contracted to the
body, and but very rarely stretched out posteriorly. But the antennae
appear always to maintain their extended position during flight, but
which position is transformed in the Cerambycidce, furnished with long
antennae, into a gentle curvature inclining outwards and backwards.
In this position they contribute much to maintain an equilibrium with
the abdomen, that it may not sink still lower.

This inclining posture of the whole body is, however, of no conse-
quence to the execution of flight, but the likewise oblique attachment
of the wings to the thorax is especially so. This oblique attachment
is distinctly seen if a line be drawn through the direction of their
affixion, and this is conceived to lie in the plane of the axis of the
thorax when both are found to cut closely behind the thorax, and even
sometimes upon its posterior limits *. The wings consequently during
flight do not move perpendicularly to the body, but on an oblique plane ;
and are also acted obliquely upon by the pressure of the air, so that
upon rising they appear bent upon the posterior margin, and upon
sinking they also appear raised. This difference of osture is occasioned

* See Plates IX.— XIV.

460

PHYSIOLOGY.

by the irregularity of the nervures, for upon the anterior margin
stiff, firm and inflexible nervures are found, but upon the posterior
margin there are none, and in its vicinity there are only soft, thin and
flexible ones. Also the oblique position of the wing to the direct plane
of its motion effects the entire progression in the air ; so that by the
pressure of the air going obliquely against the surfaces of the wing, it
acts like any other power upon an oblique plane which admits of being
divided into two so called parallelograms of force, one of which is lost,
but the other acts perpendicularly, yet somewhat less effectually than
the original force. An equal force, which, like that of the stroke of
the wing, presses downwards, presses also upwards in the stroke, which,
likewise, may be divided into two forces, one of which is lost. We
thereby acquire, therefore, two moving forces, both of which, it is true,
stand perpendicularly to the wings, but yet cut each other in their
direction, as the posture of the wing is different in its rising and sinking.
These two moving forces consequently form, when we add to them
their parallels, a third parallelogram of forces, and the diagonal of
this parallelogram, drawn through the angles where both forces meet
in the horizontal plane fixed by the centre of gravity, describes the
line of flight.

Had not nature concurred in all these adaptations, had, for instance,
the surfaces of the wings stood at right angles to the plane of motion of
the wings, progression in the air could not have taken place, but the
insect must necessarily have stopped short in the air upon the very first
stroke of its wings, as the pressure from above and beneath would have
been opposed in a linear direction, and, in consequence of the rapidity
of the motion of the wings, would have neutralised each other. But
this is actually the case in some volatile motions, namely, in hovering,
or the stopping at one spot in the air. The insect can give voluntarily
such a posture to the wings, that the propelling forces oppose each
other in a linear direction, and the consequence of which is, that it
remains hovering at one spot in the air. But it requires much exertion,
whence it is that the strokes of the wings follow each other more
rapidly, and the buzz during it is shriller and louder. We particularly
observe this capacity of hovering in the Diptera, which, in consequence
of the narrowness of the base of their wings, possess the power of moving
the wings on all sides, and among them again we observe it most perfect
in the Bombylii , Anthracodea, and Syrphodea , likewise in many true
genera of flies, viz. Miliogramma. This order also is distinguished

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461

from the rest with respect to their flying apparatus, by being deficient
in posterior wings, instead of which they possess balancers. We have
before ( § 1 68 ) expressed our opinion of their supplying the place of
posterior wings ; modern experiments have confirmed this opinion in as
far as they anatomically agree with the wings, namely, in consisting of a
simple but somewhat more compact neurated membrane, which, as well
as the membrane of the wing, is a continuation of the epidermis, and
forms a closed, and, in these, a smaller pedunculated bag. Into this
peduncle a tolerably thick trachea passes, but which, however, is not
more than half as thick as the foot-stalk, and which, as soon as it
reaches the knob, ramifies within it in many branches. With respect
to the function of this poiser during flight, Schelver* has already
proved that they are essential to it. He cut off the balancers of
several Diptera ; they indeed still flew, but only short distances. I
have convinced myself of the correctness of his assertions by many
experiments : every fly which was deprived of these organs had lost
the art of flight ; they indeed flew a distance of from one to two feet,
but then rolled over, and fell to the ground. If then they were
urged, they made a fresh endeavour to fly, but which again failed in the
same way, as well as in all subsequent ones. To convince myself if
any other mutilation of the body would affect the capacity of flight, I
now likewise cut off the scales, but the result did not justify my
expectations. Erislalis tenax flew with the same rapidity and skill
after as before the operation, the same as if it had suffered no loss.
Schelver, indeed +, gives a different result to the same experiment, but
he errs ; I have frequently repeated my experiment, and always with
the same consequence. The results to the capacity of flight from the
loss of the legs are also not correct, for a Tipula , from which I removed
every leg but one, flew as well as before the experiment, but the loss
of all the legs appears to injure that operation.

§ 267.

Having thus explained the different motions of insects, we still have
to make a few general observations upon the force and duration of
muscular motion. Both attain a degree in insects which remain to be

* Beobacktungen über den Flugund das Jesumme einiger Zweiflugligen Insekten.
Wiedemann’s Archiv, vol. ii. Ft. 2, p. 212.

•f* lb. No. 4.

462

PHYSIOLOGY.

discovered in other animals, and is probably nowhere surpassed. I
think I discover the cause of this, for such small and insignificant
creatures, remarkable phenomenon in the preponderance of their
respiration ; for wherever we meet with the function of respiration,
and especially of the respiration of atmospheric air, preponderating, we
find in conjunction the faculty of powerful and continuous muscular
activity. Thus in this view also there is an affinity between insects
and birds, as both classes exhibit the high importance of respiration
to the entire organisation, and, as a consequence, the most powerful
muscular activity.

The muscular power exhibits itself likewise in each of the four
several modes of motion. The rapidity with which certain insects
progress on foot is admirable, and presents itself in a very distinguished
degree in the last family of the beetles, namely, the Carabodea. Their
allies also, the Staphylini , display very rapid motions both in running
and in flight, but especially in the former. Even among the most
minute insects do we find rapid runners, for instance, among the flies,
in which the genus Tcichydromia of the family Empidodea derive their
name from it. But it is not solely in the rapidity of their motions
that we recognise the muscular power of insects, but also in their
faculty of coursing about upon perpendicular walls and vibrating
surfaces. This faculty they especially owe to their sharp claws, and
to the clinging organs placed at the extremity of their foot. Many of
these, namely, th e pulvilli of the bees, wasps, and flies, are true sucking
cups, which at first lay themselves flatly upon the object, and then by
their concavity and rarefaction of the air beneath them clutch closely
to it. But yet considerable muscular power is requisite for an animal
to continue hanging with its whole body suspended by its own limbs
by voluntary muscular force.

Still more admirable is the rapidity with which many insects
that prepare for themselves cavities and subterranean dwellings are
able to execute them. This rapidity also presumes great muscular
power, and especially a great duration of the force. How rapidly, for
instance, does not the larva of the ant-lion dig its pit, which can
receive within its cavity at least a dozen insects of its own size ! How
speedily do not the fossorial wasps dig a hole for the reception of their
eggs after they have first placed in it a caterpillar as large as them-
selves, and frequently weighing at least half as much again ; and yet
the common Ammopkila sabulosa carries off its prey with the greatest

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463

facility ! Who has not observed an ant-hill, and admired the industry
with which these little creatures labour ! Whom has the fact escaped
that two or three pismires, or, according to the size of their prey, live
or six of them, convey away a large caterpillar, which has by accident
come within the limits of their fortifications, and bear it, notwith-
standing its violent resistance, to their purposed spot ! In such
undertakings they frequently work in opposition to each other, and,
under such circumstances, the colossus remains for a time immoveable,
retained by equal powers acting in opposition to each other. Lastly,
the burying-beetle, how quickly does it not bury its corpse ! From
four to six of them are sufficient to bury a moth several inches deep in
the course of a quarter of an hour, and even a single beetle would
execute this certainly monstrous labour in the course of an hour. Let
us only reflect upon the capability of even a dozen men burying a whale
in one hour ; and yet the proportions with respect to size are more
favourable to the execution of the project in this last case than in the
former.

But the force and duration of muscular motion exhibits itself most
conspicuously during flight. We admire the continuous flight of the
migratory bird and the rapidity of the swallow, and yet the most
common insects exhibit the same phenomena. The well-known dung-
beetle flies in warm summer evenings with a rapidity which yields in
nothing to the swallow, although it is not one-tenth part its size. The
(Estri, Tabani , and flies which pursue cattle and horses with a voracious
thirst for blood, excite by the humming noise of their flight the poor
objects of their rapacity to escape by resorting to their quickness, but
they do not thereby secure themselves from their persecutors, who,
quicker than them, at last discover a suitable place of their body for
the exercise of their parasitic occupation. We may frequently convince
ourselves of their rapidity when riding upon a horse about to be attacked
by an (Estrus , upon spurring it to its full speed, for it constantly
remains in the vicinity of the animal, at about two or three inches
distance from its body, and even at last, when convinced of the im-
possibility of executing its purpose, it flies away still faster than the
rider, preceding him with incredible rapidity upon his own path. The
most remarkable instance of this kind is possibly that related by an
English traveller *, who was travelling with a steam-carriage that was

* In the Philosophical Magazine.

464

PHYSIOLOGY.

propelled at the rate of twenty miles an hour. This carriage was
accompanied a considerable distance by a humble-bee ( Bombus subinter -
ruptus, Kirby), not merely with the same rapidity, but even with
greater, as it not unfrequently flew to and fro about the carriage, or
described zig-zag lines in its flight, in addition to which the wind was
against them. Leeuwenhoek relates an instance in which a swallow
in a long avenue pursued a Libellula of the genus Agrion for the space
of an hour without catching it*; the little creature continued at least
six feet below its pursuer, and at last escaped it. These few instances
will convince us of the muscular power of insects. A detailed descrip-
tion of their different modes of flight would lead us too far ; we
consequently refer to Kirby and Spence’s Introduction to Entomology :
in the 23rd letter in the second volume will be found an interesting
collection of such instances.

We have as yet cited no convincing instances of the duration of
muscular motion, but they are in fact of rarer occurrence than those
which exhibit the power and rapidity of flight. Certain phenomena,
however, namely, the migrations which certain insects occasionally
undertake, prove that even in this view the power of insects is not
insignificant. As a wandering insect, the migratory locust is most
celebrated. We do not here speak of the devastations that this terrible
creature frequently produces, but merely of its flight. This is indeed
but slow and heavy, for the locust flies but a short space above the
ground, unless opposing objects intervene and cause it to rise higher,
yet still of not shorter duration. In their migrations, which, in 1774,
devastated Siebenbürgen and Hungary, and which even advanced as
far as Vienna, swarms were observed several hundred fathoms thick,
one of which occupied four hours in passing a high tower, and thus
long at least must every individual have flown. The intelligence of
an American newspaper is still more striking f, which relates that the
ship Georgia, upon its voyage from Lisbon to Havannah, upon the 21st
of November, was in the vicinity of the Canary Islands, but yet 200
English miles from land. A calm came on, which was succeeded by a
light wind from the north-east. Now for the space of a whole hour
locusts fell upon the ship and the surrounding sea, which covered its
entire surface, yet they were not at all fatigued, but jumped and
endeavoured to escape their pursuers. If we even conclude that these

* Kirby and Spence, Introd. vol. ii.

t lb. vol. i.

OF MUSCULAR MOTION.

465

locusts were conveyed even a considerable distance from land by high
winds, yet must a great portion of their journey be ascribed to
their own continuous muscular power, for otherwise they would have
fallen much earlier into the sea, but as the abated wind no longer
supported their flight like the violent one, their strength decreased and
they fell down. Other instances are found of the continued voyages
of Libelluloe to considerable distances. We have before mentioned the
rapidity of their flight in a case observed by Leuwenhoek. Indeed
these little creatures do not more excite our astonishment by the light-
ness and rapidity with which they fly, than by the duration of their
motion. They incessantly swarm and hover about meadows, brooks
and ponds, their favourite places of resort, without ever reposing any
length of time ; and as if they wished to excite still more the rage
of their pursuer by their playful motions, they hover in front of him
the moment he thinks to capture them, and yet do not allow him to
attain his object. Several instances are on record of their migrating
in vast multitudes. Kirby and Spence in their classical work *
have cited several, and I myself have twice been an eye-witness of such
migrations. They proceeded rather low, in innumerable multitudes,
in an undulating body over the heads of their astonished spectators,
without the least apparent cause of their collection or migration
offering. On the evening of the day they dispersed, and on the follow-
ing day, all the streets of the town over which the swarm passed were
animated by the returning members of this numerous society.

We will here conclude our description of the motions of insects.
Much that was highly interesting and much that might be still said
upon these subjects from the natural history of these creatures, we have
necessarily left unnoticed, as our object was but to state the chief
results and most general phenomena. The very interesting work of
Kirby and Spence contains such a multitude of these details, related in
a charming style, that, had we wished to have been more copious, we
could but have repeated their animated description. We must conse-
quently refer our readers for what relates to the external relations of
insects entirely to the work of those learned and well-informed gentle-
men.

* Introduction, vol. ii. p. 12.

II II

468

PHYSIOLOGY.

FIFTH CHAPTER.

OF THE SOUNDS AND NOISES EMITTED BY
CERTAIN INSECTS.

§ 268.

The investigation into the sounds emitted by insects during their
motions does not inappropriately follow the description of these several
motions, for the causes of these sounds appear to exist in these motions
themselves. It was formerly supposed that the majority of these sounds
were produced by the motion of the wings alone, without taking the
least consideration of the apertures that are found upon the body of
the insect, and through which, upon every respiration, air streams in
and out. The mechanical friction of the wings together, or of the
latter against the thighs, were considered as the causes of the loud cries
of many grasshoppers and locusts, and also the vibration of the air
caused by the strokes of the wings was considered as all that produced
the hum in the flight of bees, wasps, and flies. If even the friction of
portions of the integument together, for instance, of the pronotum upon
the face of the mesonotum in many beetles is apparently the sole cause
of the noises emitted by them, yet in the majority of other instances a
mere mechanical friction is not sufficient to produce so strong and shrill
a tone, for it is doubtlessly frequently the air streaming out of the stigma,
and thereby putting vibratory bodies in motion, that produces these
sounds : and just as easily as this is considered to be the cause of the
noises emitted by the Cicada , may it also be proved to be that of
the humming of the bees, wasps and flies. An experiment of this
description is the theme of the present chapter : we therefore pursue
the path, in our investigation of this subject, which nature seenis to
have traced, and shall commence with the sounds produced by mere
mechanical friction, which will be followed by the hum heard during
flight, and we shall conclude with such noises as are produced by
peculiar organs.

OF SOUNDS.

467

§ 269.

By the friction of parts of the integument together, all those sounds
are produced which we observe in beetles of the different families. The
best known family in this respect, and which also produce the loudest
sounds of this description, are the capricorn beetles. Almost all the
species of this very extensive group emit, upon being touched, a
tolerably loud, chirping, uniform sound, varying only in its intensity,
and which is produced by the friction of the posterior margin of the
pronotum upon the prolonged anterior portion of the mesonotum which
projects somewhat into the cavity of the prothorax. Both the surfaces
are very smooth, but not otherwise distinguished, so that the mere
mechanical friction of the one against the other must be regarded as
the sole cause of the sound produced. Indeed the same sound may be
produced after the death of the creature, by rubbing the two parts
together. Whether this sound have any determinate purpose, for
instance, attraction, cannot be decided with certainty, but thus much
is the case, that both sexes equally produce it, and, particularly,
only in such situations as affect their free and voluntary motion. I
have never found that any Cerambyx made it, unless disturbed or
touched, and precisely when those restraints were most violent the
sound was then loudest ; for instance, when impaled by a pin, and
he endeavoured with all his limbs to free himself from his thraldom.
The same is the case in all other insects which produce sounds by the
same means. We also detect similar sounds in the dung-beetles, viz.
in Geotrupes ster cor arms y vernalis, Copris lunaris, and others of the
family of Lamellicorns, as in Trox sabulosus. The only difference is,
that these beetles produce it by rubbing the abdomen against the
elytra. Of this we may easily convince ourselves by taking such a
beetle between our fingers, and turning its belly upwards ; we then
distinctly see the up and down motion of the abdomen. The sound is
also prevented if a pin be introduced between the abdomen and the
elytra, so that the former cannot touch the latter. The burying beetle
( Necrophorus vespillo), the lily beetle ( Lema merdigera, and another
species of this genus), even a swimming beetle ( Hygrobia Hermanni,)
and many others, produce similar sounds in the same manner. Indeed,
according to Latreille*, the Pimelias emit similar sounds by rubbing

Hist. Nat. torn. x. p. 264.

H H 2

468

PHYSIOLOGY.

either their legs together or against the body. Bugs also (viz. Cimex
[ Reduvius ] subapterus, De Geer*) and the Mutillce (M. Europcea )
produce such sounds upon being touched f, the former by the motion
of its head, probably, therefore, by rubbing the occiput against the
margin of the prothorax.

Hence, consequently, all these sounds are doubtlessly expressions
of pain or displeasure, precisely as many of the higher animals only
under similar circumstances make their voices heard, but have otherwise
no use for them.

§ 270.

The second kind of sounds which insects produce are those which
wre hear during their flight, and especially by the Hymenoptera and
Diptera, but also by the beetles, Orthoptera , and bugs. That these
sounds are not produced solely by the flapping of the wings, we may
easily convince ourselves, for if the wings be cut off, the fly produces
its former sound, although somewhat weaker. Hence, therefore, the
question occurs. Which is truly the organ of sound ? The reply will
readily suggest itself when we shall have first more closely investigated
the conditions under which the noise originates. If any fly, for instance,
the very common Eristalis tenax , be held by the legs, and the wings
left free, it will endeavour by the violent motion of its wings to
emancipate itself, and emits a loud buzzing sound. If the wings be
half cut off, the vibration of the wings continues, and the sound becomes
shriller ; but if they be quite cut off, we observe their roots still in
motion, and the sound becomes a little shriller, but also weaker than
before. Thus, therefore, the presence of the wings has no influence
upon the production of the sound, and at most but a trifling one in
causing a change of tone. But there are other organs besides the wings
upon the thorax which might be the causes of the sound, namely, the
scales behind the wings, the poisers, and the spiracles which lie between
the meso- and metathorax. If the scales be removed, the sound is not
at all affected ; it remains unchanged as long as the wings can vibrate.
If the poisers, lastly, be cut off1, this produces no difference of sound,
and a fly deprived of all the external organs which tend to assist the
flight, can, so long as the mere stumps of the wings remain to vibrate,
produce a distinct but somewhat weaker and higher sound. The
spiracle alone remains, therefore, to be considered as the cause and

M^moires, tom. iii. p. 190.

t Kirby and Spence, vol. i.

OF SOUNDS.

469

instrument of the sound. To convince myself of this, I closed both the
spiracles with gum, and then urged the fly to vibrate its wings, but it
was scarcely to be induced to do so, yet when it occasionally tried it, no
sound was produced ; only after an interval, when the spiracle was freed
from its stoppage by means of violent volatile motions, was the sound
renewed. There is no doubt, therefore, that the air streaming from
the spiracle is the cause of the sound, and that a body which by this
draught of air is brought into vibration, must necessarily stand in
connexion with the spiracle. I therefore cut out one of the spiracles,
opened it carefully, separating the angles of the incision, and soon found
what I sought, namely, the vibrating body, and not one only, but very
many. That lip of the spiracle, namely, which lies posteriorly, and also
somewhat inwardly, and which is lengthened upon its inner side, that is
turned towards the commencement of the trachea, is formed into a small
flat half-moon-shaped plate ; upon this plate there are nine parallel very
delicate horny leaves, the superior free sharp edges of which are bent
somewhat downwards, so that the anterior one inclines a little over
the rest. They are also higher towards the trachea, and towards the
margin of the spiracle lower, and the central one is the largest, from
which on each side they gradually become smaller and lower. Upon
the air, which is driven with force out of the trachea, touching these
laminae, they are made to vibrate and sound precisely in the same
manner as the vibrating of the glottis of the larynx. Thus, consequently,
there is no insignificant analogy between the spiracles and the larynx,
particularly of birds. To convince myself that it was merely the
posterior spiracles of the thorax which emitted sounds, I likewise
inspected the anterior ones, but found in them not the least trace of the
just-described laminae at the inner side of the posterior lip*.

We can now comprehend the reason of the change of tone on the loss
of the wings. The vibrations of the contracting muscles can no longer
be so intense in consequence of the loss of the organs made to vibrate,
and in consequence of the weaker contractility, the air cannot be expired
with the same degree of force. The tone is therefore weaker than
when the wings were present ; also, as Chabrier supposes, some air may
escape through the open trachea of the wings which are cut off.

* Chabrier, in his Essai sur leVoldcs Insectes, p. 45, &c., likewise explains the hum of
insects as produced by the air streaming out of the thorax during flight : he also speaks
of laminse which lie at the aperture of the spiracle ; hut I cannot recognise from his
description whether he saw these or others.

PHYSIOLOGY.

47a

Whether the structure and situation of these vibrating bodies be the
same in all buzzing insects, I cannot for the present decide. Another
work, devoted exclusively to this subject, will impart all the details
that I may discover ; but for the present, thus much is determined.
Delicate laminae are found at the entrance of the posterior spiracles of
the thorax, which are set in vibration by the streaming in and out of
air, and which are the cause of the humming noises produced by bees
and flies during their flight. In the buzzing-beetles, for instance, the
cockchafer, I could not discover such laminae near the aperture of the
thoracic spiracles, and in these, therefore, the outward streaming air
must be the sole cause of the tone ; physics teach us also that a stream
of air made to pass through any aperture with violence will produce a
sound. In fact, the tone of the humming-beetles is weaker, pro-
portionately, than that of the much smaller Diptera , and we may thence
trace the cause of it to the deficiency of the vibratory laminae.

§271.

The sounds that are produced by peculiar organs solely adapted to the
purpose are found only in two orders, namely, in the Orthoptera and in
the Hemiptera ; in both cases they are in general peculiar to the male
sex alone, and the females are then dumb. The male Orthoptera , in
which we observe such organs of sound, bear them always at the base of
the superior wings. Among these the genus Acheta and Locust a
possess them. In both it is a round, flat, shining, very thin plate,
seated at the base of the wing, immediately behind the large main
nervures, which appear to produce the tone. The following is doubt-
lessly its mechanism. By means of the violent volatile motions which
agitate the whole body, but during which the wings are not expanded,
the air is driven out of the spiracles, and especially out of the central
ones of the thorax, and thus bounds against the inflected external
margin of the superior wing, which is pressed closely to the thorax.
It must necessarily, therefore, to find an exit, rise beneath the wing, in
order to escape from it beneath the posterior margin. Pursuing this
path, it precisely strikes upon the just described elastic field of the
superior wing, which vibrates through the pressure of the air, and
consequently emits the sound. To corroborate this view I have cut off
the wings of several locusts, but they never subsequently made any
noise. It is here, therefore, the wings or the vibration of the elastic
base of the wings, which produces the sound upon the motion of the

OF SOUNDS.

471

wings. The shrill tones of the grasshoppers, locusts, and field crickets
are therefore tolerably alike, varying merely in intensity. The tone
of the cricket is probably the weakest, and that of the grasshopper
perhaps the strongest. According to Kirby and Spence * the mole
cricket is said to produce a dull tone resembling that of the goat-sucker,
but I never heard it ; and in the insect itself I have not been able to
find anything analogous to a vocal organ.

In the remaining Ortkoptera which possess a voice, namely, in the
genus Gryllus, Fab. (Acrydium, Lat.), it is equally found in both sexes.
The organs which produce it lie at the base of the abdomen, upon its
first segment, one on each side, immediately behind the first abdominal
spiracle. Each presents itself as a half moon-shaped cavity, closed at
its base by a very delicate membrane, which is sometimes wholly free
( Gryllus stridulus ), and at others half covered by a triangular plate,
projecting from the anterior margin. Close to the anterior margin of
this fine membrane there is a small, brown, horny spot, upon which
internally a delicate muscle is inserted, that runs over to a projection
of the external horny plate which lies over and in front of the margins
of the spiracle. By means of this small muscle it is made to vibrate*
and consequently sound, when the whole body is agitated by the
volatile motions. The sound thus produced is increased by a large air
bladder, resembling a distended trachea, lying beneath the fine mem-
brane, which re-echoes the sound like a sounding-board. But the tone
thus produced is, however, weak, but it is loudest in the thence named
Gryllus stridulus , and possesses no other differences than in intensity
and weakness. Formerly it was thought that the friction of the pos-
terior thighs against the wings was the sole cause of the chirping of
these creatures, an opinion founded upon the contemporaneous motion
of the wings and hind legs. Indeed, such a friction of the hinder
femur against the inflected margin of the superior wing appears to
participate in the mechanism of the sound, for even after the death of
the creature I could produce a similar but much weaker sound by
rubbing those parts together. Thus the allied genus Acrydium, F.,
( Tettix, Lat.) appears to produce the weak tone which it emits, for it
has no vocal organ like Gryllus. The African genus Pneumora, Lat.,
also is said to produce a sharp chirping noise by the friction of the
femur against the abdomen, or small ridges seated upon it. De Geer
even detected the vocal organ of Gryllus, and considered it as such.

* Introd. vol. ii.

472

PHYSIOLOGY.

but he did not clearly comprehend its true mechanism * during chirp-
ing. Joh. Müller has latterly described it as an auditory organ -j-.

It is in the family of the Cicada, namely, the larger ones ( Tetiigonia ,
Fabr., Cicada , Lat.) that the voice attains its highest degree. In
these creatures also we find the voice possessed exclusively by the
males^ and it is produced by an organ that has the greatest resem-
blance to that of the Grylli. In these it is also an elastic membrane,
which is longitudinally folded and stretched over an oval horny ring
seated immediately behind the first large spiracle of the abdomen,
which, by a peculiar muscular apparatus, is made to vibrate. To each
of these elastic membranes a strong conical muscle runs, which, with
its broad basal surface, is attached to a plate-shaped horny tendon, the
short pedicle of which is in connexion with the drum, and which ori-
ginates at a central, furcate, horny process of the ventral plate of the
second abdominal segment, the analogue of the furcate process of the
breastplates. This muscle, together with the membrane, constitutes
the vocal organ. If the abdomen, by the respiratory motion, be expanded
or contracted, this muscle likewise stretches, whereby the membrane is
made to vibrate, and consequently resound. The sound is increased, as
in the Grylli , by means of a large air bladder, which lies at the lateral
portion of the abdomen, and which closely covers the muscle as well as
the membrane. In this cavity the sound rebounds, and thus proceeds
more strongly from the insect. As external organs, there are, in addi-
tion to this vocal organ, some other parts which serve as a cover to it,
but which are not of importance to the production of the voice, namely,
two half circular horny plates, which spring from the margin of the
horny integument in front of the drum, and more or less cover it ; also
beneath the drum in the centre of the ventral plate of the segment
behind the coxae of the posterior legs there are two small, oval, trans-
parent fenestrations filled by a tense membrane, but which likewise
appear to stand in no direct causal connexion with the voice. In the
female also these little fenestrations are found, although less perfect, as
well as the external valves which cover the drum ; but there is not the
least trace of this itself, nor of the muscle which moves it. The air-
bladder the female likewise possesses, but it is smaller than in the
male J.

* M&noires, vol. iii. p. 471, PI. XXIII. f. 2 and 3.

+ Zur vergl. Physiol, der Gesichtssinne, p. 438.

+ Compare, upon this vocal organ, the Treatise of Carus in the Analekten zur Natur-
wissenschaft und Heilkunde. Dresden, 1829. 8vo. p. 151.

OF SOUNDS.

473

At the close of this description of the several organs whereby insects
produce peculiar sounds, we still have to speak of the sound and the
mechanism that produces it in a Lepidopterous insect, the well-known
death’s head moth ( Acherontia atropos, O.), which it emits upon being
touched or disturbed. Reaumur and Rossi were both acquainted with
the plaintive cry of this moth, and expressed their opinion that it pro-
ceeded from the friction of the tongue against the palpi. More recently,
the experiments which Passerini has made to ascertain the organ which
produces this sound have proved that it must lie somewhere in the
head. He found a cavity in the head which has connexion with the
false canal of the tongue (or rather, it should be said, with the central
canal formed by the application of the two halves of the proboscis
together), and about the entrance to which muscles lie which rise and
sink alternately, and by these motions drive the air out of it and re-
admit it. I do not, however, distinctly see how the mere streaming in
and out of air could produce so loud a noise, if at the entrance there
be not some body made to vibrate by its passage. Such must therefore
be shown to exist, to explain fully the mechanism whereby the death’s
head moth produces its. plaintive cry. I have not yet possessed a living
individual of this otherwise not uncommon moth, I can therefore say
nothing from my own experience ; according to Duponchel *3 whom
we have to thank for the communication of Passerini’s observations,
there is a delicate membrane stretched between the eyes and the base of
the proboscis, which certainly might be the cause of the sound if we
adopt that the above cavity immediately adjoins it, and that it is made
to vibrate by the air passing to and fro. Duponchel found this mem-
brane also in Sphinx Convolvuli , which, however, produces no such
sound ; but then the internal cavity may be wanting whereby the faculty
of causing the membrane to vibrate, as in the death’s head, is lost, and
it is consequently dumb. Passerini purposes making his observations
public, which will then doubtlessly spread more light over this inter-
esting subject. Thus much, however is certain, that the death’s head
moth makes a peculiar plaintive cry, which is produced by a particular
organ seated in the head.

* See Annales des Sciences Naturelles, tom. xiii. p. 332 (Mar. 1828), and Hcusinger
Zethshrift für die Org. Ph vs. vol. ii, part iv. p. 442.

474

PHYSIOLOGY.

SIXTH CHAPTER.

OF SENSATION AND THE SENSES.

§ 272.

The functions of the nervous system are certainly among the most
problematical of all the animal organs. Even in the higher animals,
in which observation is more easy, and it has to contend with fewer diffi-
culties, much still remains in impenetrable obscurity, notwithstanding
the light that has been given in modern times to this portion of phy-
siology ; it will therefore strike us as less singular if the most general
phenomena of the functions of the nervous system of the lower animals
have not been satisfactorily explained. We move here in a field where
simple experience frequently quits us, and a wider space is given to
the fancy for its hypotheses and inventions. Yet we will keep ourselves
as far as possible from this frequently misguiding conductress, and only
endeavour to explain what our own experience and that of others
enables us to do satisfactorily.

It accordingly appears confirmed that the nervous system, and chiefly
the first chief ganglion or the brain, is the truly animating element
which sets all the other organs in activity, and retains them in it.
From the nervous system the muscle derives the irritability which puts
it in action ; by means of the nerves the intestinal canal is excited to
digestion, and by the impulse of the same organs the sexual parts
exercise the function appointed to them. Lastly, the nerve is the
recipient and conductor of all immediate perceptions of external objects,
and consequently the seat of sensation in general. Experience corro-
borates all these assertions. With respect to the effect of the nerves
upon the muscles, we know from Rengger’s * experiments, that after
the nervous cord has been cut through at any part, the portion of the
body which lies beyond that spot can exhibit no more motion. Rengger
repeated this experiment in different kinds of caterpillars, some of
which he cut through at a higher and others at a lower part of the

Physiologische Untersuchungen, &c. p. 41.

OF SENSATION AND THE SENSES.

475

ventral cord, and the same result always ensued. The legs which lay
behind the scission no longer executed their function, but appeared as
dead. The segments of the body also became flaccid and motionless,
and only at isolated spots catchings of the muscles were to be observed.
If the caterpillar were now carefully opened it was seen that the
posterior portion of the stomach, namely, that which lay beyond the
scission, no longer exercised its peristaltic motion, and that its contents
no longer passed into the ilium, and also that the indigestible remains
contained in this portion, as well as in the colon, were no longer ejected,
but that entire part of the intestine appeared lifeless. The anterior
portion acted however as usual ; the caterpillar still ate and crept about
with its anterior legs as if fully enjoying its preceding state, dragging
its insensible lamed posterior portion along with it. If, lastly, the
scission which separated the nervous cord were very near the head, so
that thereby the lamed portion considerably preponderated over that
still capable of motion, the latter was likewise hindered in the full
exercise of its function, the caterpillar could then no longer crawl,
although it exercised the requisite motions with its anterior legs, yet
the preponderating lame posterior portion prevented its moving from
the spot. Upon the nervous cord being separated at so high a spot the
vital system was considerably affected, and the caterpillar soon ceased
to live, but the further backwards the cut was made the longer the
caterpillar lived, and the less was the exercise of its functions
disturbed.

The irritability of the muscles beyond the point of separation was
not yet wholly lost by the cutting, they speedily contracted after con-
siderable pressure, but immediately became flaccid upon the removal
of the exciting cause. The motion of the stomach also continued at its
superior extremity, even when the nervous cord was cut through
between the second and third pairs of legs, as this portion of the
stomach received its own nerves from the pharynx ; but if this nerve
running from the pharynx was separated the peristaltic motion of the
anterior portion of the stomach likewise ceased, and the entire function
of digestion suddenly stopped.

Hence the brain appears the true seat of the animating forces, which
are transmitted from it by means of the nerves to the most remote
organs. The more distant therefore from the brain the wound takes
place, the less is the disturbance that it occasions to the system, but
the closer to the brain the more fatal is the operation.

476

PHYSIOLOGY.

But, to obtain a positive result, Rengger now made his experiments
immediately upon the brain itself. He first laid it bare, and by some
further incisions he removed it, and carefully closed the wound. The
creature made, even during the operation, several convulsive motions of
the whole body, which continued for a space of time after the removal of
the brain, but then ceased, upon which the body appeared as in a para-
lysed state ; the caterpillar could no longer eat, could no longer walk, but
struggled first forwards and then on one side or the other ; the peris-
taltic motion of the stomach disappeared, and only here and there did a
fasciculus of muscles still catch. But, just as in the preceding expe-
riments, the muscles retained their individual irritability, and reacted
upon the application of stimulants. Rengger, that he might avoid
the hemorrhage and other violent effects which necessarily occur in
such operations, wounded and removed the brain with a red hot needle,
but still the loss was accompanied by the same phenomena.

§ 273.

Treviranus’ observations *, however, do not harmonise with the con-
clusion deducible from the preceding communications of an important
preponderance of the brain over the other ganglia. He saw a Carabus
granulatus after its head was cut off still run about and seek a way to
escape by ; even after the removal of its prothorax the creature exer-
cised its former voluntary motions, until, upon the removal of the meso-
thorax, they died away in irregular catches. The head of Tabanus
bovinus was cut off, and it was then laid upon its back, when it made
every possible endeavour to resume its usual position, and laid hold of
a pencil offered it, and thereby crept up. Other insects, which were
injured only upon one side, directed their motions towards the un-
wounded side. Thus an Orgyia pudibunda, O., of which the left an-
tenna was cut off, kept running in a circle towards the right side, and
continued this motion even when it had lost the entire left side of its
head ; when, however, the whole head was removed, the creature made
violent exertions, running in circles, sometimes on one side, sometimes
on the other. The same moth lived three days without its head, and
continued to move its wings violently until its death. A different
result was however produced when Treviranus removed the antenna of
a wasp, for it moved indifferently on both sides. JEschno forcipala

Das Organische Leben, vol. ii. parti, p. 192,

OF SENSATION AND THE SENSES.

477

also lived four days without its head, and even evacuated excrement
during this period, but it could no longer move its wings, and was
sensible only to pressure made at its caudal extremity. Treviranus
also cites an experiment of Walckenaer, in which Cerceris ornata had
its head cut off just as it was entering the cells of Halictus terebrator,
when it still continued its endeavours, and even turned round towards
the hole upon being placed in a contrary direction.

§ 274.

To endeavour to harmonise these discordant results, or rather, to
ascertain to which the preference was truly to be given, I myself insti-
tuted the series of experiments which follow.

Among the Coleoptera it was chiefly the water-beetles, viz. Dyticus
sulcatus and cinereus, which I made use of. I first took the male D.
cinereus, and cut ofif its head, but the crop and proventriculus were also
thereby removed from the body ; from the very instant it totally ceased
all voluntary motion, but upon pinching the feet severely with a pair
of pliers a strong reaction of the muscular irritability was produced ;
the posterior legs immediately made three or four swimming motions,
but they then remained in their preceding lifeless and gently bent
position. This reaction continued, but constantly decreasing in force,
for about half an hour, after which the severest pinching was not able
to produce it.

I opened the breast of a lively female Dyticus sulcatus, between the
second and third pairs of legs, so that the nervous cord was laid bare.
With a pair of pliers I now laid hold of the nervous cord, and removed
it ; the left posterior leg was immediately lamed, but the right one
and all the four anterior legs still exercised their voluntary motions,
and the creature could still tolerably swim when thrown into the
water. When placed upon its back, the contractions of the muscles
were distinctly seen. These continued for about an hour, the posterior
legs then lost all motion, and even their irritability, whilst the anterior
ones still possessed it, but yet a decrease of animation was learly seen,
and in about three hours afterwards it was completely dead.

In another male Dyticus sulcatus I separated the nervous cord close to
the soft connecting membrane between the pro * and meso-thorax ; in
the course of a few seconds the motion of the four posterior legs ceased,
whilst the anterior ones retained their perfect mobility, but signs of
irritability still presented themselves. The anterior legs, even after

478

PHYSIOLOGY.

four hours, still exercised their Voluntary motions, although with less
vivacity, but in the evening the insect was dead.

In a fourth perfectly animated male Dyticus sulcatus , by an incision
which removed the horny integument of the head, I laid the brain bare.
Immediately much yellowish brown green blood streamed forth ; it was
perfectly clear and viscid, and covered the entire wound, and stood
upon the naked part like a drop of water. I thus allowed the insect to
go ; it retained its complete motion, but moved all its limbs slowly and
convulsively as if severely injured. I now removed the brain by means
of pliers ; the insect immediately became motionless as dead, and did
not move a single joint as long as it lay upon its belly. Upon my
teasing it, after about a minute it endeavoured to cling with its legs,
but this motion appeared to proceed rather from the irritability of the
muscles than from its own volition. I now laid it upon its back, and
it directly made its usual swimming motions, during which, as when
swimming, the anterior pair were drawn closely up to the breast. These
motions lasted uninterruptedly as long as the insect lay upon its back ;
if I laid it upon its belly they ceased, and the insect again moved no
limb. I now cast it into the water, when it swam upon the surface
with the greatest rapidity, impelled by incessant natatory strokes,
striking all its comrades that it met on one side by the violence of its
motions, and continued thus uninterruptedly for about half an hour.
It did not, however, descend to the bottom, nor did I see any respiratory
action in its abdomen. After this, upon the gradual decrease of the
force of its strokes, it lay upon the surface with distended legs, but
displayed irritability upon the legs being pinched; lastly, towards
evening, the experiment having been made about II a. m., all life had
vanished.

The brain was similarly laid bare in a female Dyticus sulcatus , but
the incision passed obliquely through the right eye, and wounded its
right hemisphere, whereby the insect lost the voluntary motion of the
left posterior foot. I now removed the brain entirely, and the insect
became instantly lifeless, but in the course of a few seconds the legs
recovered their motion, but not to the same extent as in the preceding
experiment. Cast into the water, this female did not swim like the
former insect, but lay with extended legs, moving with a catch some of
its joints ; these motions could be perceived, even after an hour, upon
effective excitement, but towards evening, as in the preceding experi-
ment, the beetle was perfectly dead.

OF SENSATION AND THE SENSES.

479

With grasshoppers I have made the following experiments.

A small Gryllus ( Acrydium , Lat.) I opened in the breast, between
the intermediate and posterior thighs, and removed the large ganglion
lying there. The insect thereby immediately lost the mobility of the
posterior extremities, and was also very much enfeebled, but yet
crept about by means of its four anterior legs. Having accidentally
soiled its antennae, it made stroking motions towards them with its
left anterior leg to cleanse them, and upon my taking it up by them,
it made very active exertions with the anterior legs to free itself.
I now made an incision in the same individual through the mem-
brane of the neck, whereby the nervous cord was separated, but
the oesophagus not injured. The creature at first still moved its
anterior legs, and in them there was a powerful reaction upon pressure,
and it trembled for a time afterwards, but otherwise exhibited few
signs of life ; it lay lifeless upon one side ; it did not even lie upon
its belly ; but yet there were still catchings in the feet when nipped
with the tweezers, but not in the large posterior thighs. In ten minutes
the motion of the legs considerably decreased, and in half an hour the
animal was entirely dead.

A second somewhat larger and also very active Gryllus I again cut
through the membrane of the neck ; the insect, immediately after the
incision, made violent movements with its thighs, which cast off one of
its posterior legs; the other legs exhibited irritability as often as I
pinched them, but, after the lapse of a minute, it lost all voluntary
motion, it could no longer walk, and remained quietly lying upon its
side when so placed. In half an hour it was dead.

I have besides made experiments in Diptera, namely, in some species
of Eristalis.

I separated the nervous cord of a lively Eristalis nemorum, closelv in
front of the middle legs ; those legs immediately lost their motion as
well as the right posterior leg, but it still crept about by means of its
anterior legs and left posterior one. These motions continued, but its
course was not straight, but inclining obliquely to the left. I now
made the incision deeper, to be perfectly convinced that I had thoroughly
separated the nervous cord. The left posterior leg now lost its motion,
but the fly still crept with its anterior pair, but it could no longer fly,
as was the case upon the first incision. I now cut off its head ; imme-
diately all the motion of its anterior legs ceased, but the proboscis of
the separated head still throbbed when I drew it from the cavity of the

480

PHYSIOLOGY.

mouth. These catcliings continued for a quarter of an hour, but the
body was entirely dead.

In another lively Eristalis nemorum I made an incision transversely
through the eyes, and seriously injured the brain ; the insect, however,
still retained the perfect mobility of all its legs, and crept about, although
but slowly; shortly, however, its strength decreased, it reposed quietly,
and but slightly moved upon excitement ; in an hour it was quite dead,
but still displayed slight irritability of the muscles upon violent external
excitement.

§ 275.

From these experiments, and those communicated by Rengger, we
may deduce the conclusion, that after the separation of the nervous
cord at any part, the voluntary motion of the organs seated beyond the
point of incision is lost, but that the irritability of the muscles, that is
to say, their power of re-action upon external excitement, is retained
by these organs as long as life is still present, but that it disappears
with it. It thence consequently follows that the nerve passing to the
muscle supplies the place of external excitement, and that therefore
the will can act upon the muscles only through the medium of the
nervous system. These experiments also confirm the assertion so fre-
quently repeated, that the brain is the principal of all the ganglia, and
that the causes of all the vital phenomena exist in it, and proceed from
it. The instance in which the male Dyticus swam about a considerable
time after the removal of its brain appears to contradict this conclusion,
but I am still very strongly inclined to perceive nothing but irrita-
bility in the rowing of the feet. The entire uniformity of the motion
speaks strongly in favour of this opinion, as well as the circumstance
likewise that the beetle deprived of its brain did not execute these
motions so long as it lay upon its belly on a dry surface. We may also
deduce from these experiments, that still for a short time after the
removal of the brain, not merely signs of life but even proofs of
voluntary motion present themselves, which are the stronger the
more imperfect the injury to the brain may be. We may here class
also the experiments made by Treviranus, but I doubt their entire
accuracy. How could a beetle seek ways to escape when all the
organs whereby it might perceive such opportunities were removed from
it? Walckenaer’s observation is more probable, that the Cerceris
repeated several times its preceding endeavours after the loss of its

OP SENSATION AND THE SENSES.

481

head ; it was merely a continuation of the undertaking resolved upon
previously to the mutilation, but which, however, could only continue
as long as the remainder of the nervous cord still conveyed the excite-
ment impressed upon it by the will ; that, however, after the alteration
of the direction of the motion the wasp absolutely resumed its previous
position, I very much doubt, it is improbable in every case, and my expe-
riments do not tend to substantiate it. Treviranus’ remark also, that the
Orgyia lived for three days after the loss of its head, excites just sus-
picion, for in all similar experiments of mine life had perfectly vanished
in the course of a few hours. But I am acquainted with other
instances in which the Noctutz, after having been killed with red hot
needles, and extended upon the setting-board for a week, have not only
moved the abdomen upon the application of an excitement, but still
also continued to lay eggs. I think the reason of this may be found in
the independent irritable life of the sexual organs, which, excited by
the continual stimulus of the eggs contained within them, continue
laying them, and as long as eggs exist within them display signs of
irritability. To this class, consequently, the instance cited by Trevi-
ranus may be placed ; life no longer truly existed, but merely the re-
active power of the sexual organs, and they did react when excited by
external stimulants, but I consider the observed motion of the wings as
very doubtful ; for the needle thrust through the thorax and the other
red hot one would doubtlessly have had the same effect as removing the
ganglion situated in the thorax ; the red heat would doubtlessly have
deprived it of its activity, and thereby the motion of the parts with
which it supplied nerves would necessarily have been destroyed. We
frequently observe in insects thus mutilated a still continued motion,
for instance, in the antennae and the parts of the mouth, when the
legs and wings have entirely lost theirs.

§ 276.

The influence which the nervous system exercises upon the several
organs of the body may thus therefore be generally stated ; we have
still to consider more closely the nerves as the recipients of external
excitement, in short, as the organs of sensation in particular. It would
be difficult to obtain a satisfactory result upon this subject by experi-
ments upon insects, for, although we perceive that they are sensible to
external excitement, yet we cannot distinctly prove that they receive these
sensations through the nerves. We can maintain nothing further with

1 1

482

PHYSIOLOGY.

certainty than that in insects similar organs are found, to those whereby
the higher animals, and particularly man, feels, and that there-
fore, by means of these organs, insects likewise perceive the presence
and quality of the external objects which their body touches. But we
know, upon the other side, by means of direct observations, that insects
do feel, and we may therefore deduce from the preceding opinion,
founded upon analogy and these observations, that the nerves of insects
are likewise the organs of sensation.

Observations confirmatory of the presence of sensation in insects
daily offer ; we have but to look at some creeping insect, and observe how
it convinces itself of the presence of an object by touching it with its
antennae, and then carefully avoiding it ; and besides, insects that are
reposing are disturbed from their repose by any ungentle touch, and
upon a repetition of the disturbance quit the spot ; and lastly, pupa,
upon the least touch, and by their rapid and serpentine motions,
instantly evince a feeling of displeasure. In many pupae the sensation
of inimical influence is so delicate as scarcely to be credible ; the mere
opening of a box in which they may have been placed disturbs them,
and, indeed, some of the slightly clothed pupa of the Coleoptera , whose
natural situation is beneath the earth or in dark situations, instantly
move, and with considerable force, if a ray of light be allowed to fall
upon them, but they are peculiarly sensitive to bright sunshine.

But we are most distinctly convinced of the sensation of insects upon
impaling them for the collection. Even the mere pressure of the pin
produces unpleasant sensations, which the insect expresses by the rapid
and painful motion of its limbs ; upon its point proceeding still further
the expression of disagreeable feeling increases by its more rapid and
unnatural contortions, and I have frequently observed, that at the mo-
ment when probably the pin passed through the ganglion, and when the
insect appeared as it were suddenly lamed by its excessive pain, it
extended all its limbs, and even its oral organs, and then ceased for
some seconds all motion. This motion continues for some space of
time, frequently from a week to a fortnight, as long as the insect is
teased, but it does not appear to happen in repose, or if the insect be
enclosed in a dark situation, at least I have observed many instances
in which, under such circumstances, the insect did not move. Hence,
as well as from the subordinate sensibility of the nervous system of the
lower animals, we may conclude that insects thus impaled no longer
feel any pain, and that their motion is produced merely by their endea-

OF SENSATION AND THE SENSES.

483

vours to free themselves from a disagreeable restraint. In favour of
the adoption of this opinion the deficient formation of the blood in
insects speaks, in consequence of which no inflammation and suppura-
tion can take place. Inflammation, however, or the immediate touch-
ing of the nerve laid bare, by the air or other extraneous bodies, occa-
sions our feeling pain from a wound, and as long as this irritable con-
dition does not occur no pain is felt. This irritable condition, however,
can never take place in insects, they having no blood-vessels and cellular
membrane, through which the irritable matter may transude, but merely
a lymph, circulating freely in the body. This lymph encompasses the
extraneous body, the pin, coagulates around it, and thus perfectly pro-
tects the nerves from its influence. According to this view the majority
of impaled insects die of hunger, and not by mechanical wounding ; if,
for instance, the thoracic ganglion or the nervous cord be not separated ;
for so serious an injury to the nervous system the preceding experi-
ments have shown must speedily produce death ; but yet I would not
be understood as approving of that certainly very unnecessary torture
to which poor captured insects are exposed by the young and old, as
objects of their pleasure. In support of this opinion we may still men-
tion that many impaled insects still continue the exercise of their most
usual corporeal functions ; for instance, still eat, still evacuate excre-
ment, creep about with the pin through them, and sometimes even fly,
and lastly, the Lepidoptera even copulate in this state, and, a still more
common occurrence, is their continuing to lay eggs.

§ 277-

Upon passing from these introductory observations upon the functions
of the nervous system in general to the senses themselves, we may
maintain, in reference to these, that insects are not deficient in any
important one found in the superior animals. At the end of the pre-
ceding division we described the organs of the several senses, but we
yet found only one certain organ of sense, which, with few exceptions,
is discoverable in all insects, and this was the eye. We, nevertheless,
endeavoured to discover the other organs of the senses, proceeding from
determinate observations which prove that insects have perceptions which
can only be received by senses of touch, taste, smell, and hearing, and we
then found several organs, each individual one of which admitted of being
referred to some one of these senses, either from analogous situation or
structure to that of the same organ of sense in the higher animals, and

1 1 2

484

PHYSIOLOGY.

partly from the deficiency of a satisfactory proof of a different function
of the organ. Thus we recognised in the palpi organs of touch, in the
tongue the seat of taste, in the mucous membrane of the tracheae the
sense of smell, and in the antennae, lastly, we discovered the instru-
ments of hearing. The mode whereby the insect receives perceptions
through these organs will certainly not divaricate from that found in
the superior animals. Touch, taste, and smell require the direct appli-
cation of the investigating organs to the investigated object, and so
soon as this takes place the insect perceives. We have convinced our-
selves by experiment that an insect feels objects all over with its palpi
which it wishes to inspect for food or other purposes, but that the
tongue tastes, and the mucous tunic of the tracheae smells, can only be
made probable. With respect to the latter, it is contradictory to the
views of very learned naturalists, namely, Kirby and Spence * and
Treviranus, who both adopt as the organ of the sense of smell a pecu-
liar one standing in connexion with the mucous tunic of the mouth.
With respect to its situation above the mouth, it has certainly the
analogy of all the other animal classes in favour of it, and their opinion
would even on that account merit entire approbation if absolutely the
organ of which these authors speak could there be found. But this is
not the case, and even Treviranus convinced himself by multitude of
experiments of its absolute deficiency, and so suggested the opinion that
the mucous tunic of the mouth was likewise the organ of smell, and
that therefore the sense of smell was especially to be ascribed to haus-
tellate insects only. Kirby and Spence, however, to whom the striking
contrary proof exhibited in the extremely keen smell of the bury-
ing beetle was probably present, decide absolutely in favour of a
peculiar organ of this sense, lying beneath the clypeus, and which
they call the nose, and which borders upon the mucous tunic of the
mouth. In the burying beetle they say they have discovered this organ
in the form of two circular fleshy cushions, which are covered by a beau-
tiful and finely transversely striped membrane; the same also in
Dyticus marginalis, in which it is further provided with a pair of
warts; as also in ( Eschna viatica. But the investigations of other
anatomists do not confirm these discoveries. If such an organ really
existed at the spot indicated, Straus would certainly have seen it in the
cockchafer ; and I believe I may assert, that in several endeavours

* Introduct. to Entom. iv. Letter xlv.

OP SENSATION AND THE SENSES.

485

I made expressly for the purpose in Dyticus marginalis and Calosoma
sycophanta, Hydrophilus piceus, and Scarabceus vernalis that it must
have shown itself if it had been present at the spot mentioned. In
freshly opened insects I could discover really nothing of the kind., and
in those which had been long immersed in spirits I saw the space in
front and between the clypeus and the most approximate organs filled
with nothing but coagulated blood. I cannot therefore determine in
favour of Kirby and Spence’s opinion, but prefer the earlier hypothesis,
that the internal surfaces of insects receive smell, and supply the place
of an organ especially devoted to that sense.

The majority of modern physiologists and entomologists agree in
explaining the antennae as organs of hearing, as we have already
remarked. Kirby and Spence’s representation, whose names were
inadvertently omitted to be mentioned there as the authorities for our
opinion, conveys so much conviction that we may almost consider it as
settled, although we must at the same time admit that all the difficulties
are not yet solved : we have already indicated above that the real percep-
tion of sound may possibly depend upon the trembling produced by the
vibration of the air in organs so easily moved as are the antennae, and
we here repeat^ this opinion as the explanation of the mode by which
insects hear. According to Kirby and Spence, Wollaston suggested
this opinion, and even supposed that insects could perceive much more
delicate tones than our ears are capable of distinguishing, from their
very much greater irritability. This irritability, however, in conse^-
quence of the much harder integument in which insects are enveloped,
can be possessed only by the antennae, which are so easily moveable,
and which, indeed, in many insects are in a constant state of motion ;
even the slightest vibration of the atmosphere must be sufficient to put
into motion an organ of the structure of the antennae of a gnat, and
thereby apprise its possessor of the approximation of some occurring
change ; this is equally the case with the delicate and easily moveable
antennae of the Grylli, and indeed of all insects furnished with long
antennae ; the same with the short fan-shaped flaps, as well as with the
delicately haired joints forming a knob in the antennae of other insects ;
the very structure of all betrays the possibility of very delicate percep-
tion. Organs of touch they cannot be, for their surface is too hard
and horny, and besides, all insects have for this purpose organs fur-
nished with a very delicate touching surface. Hence the mode whereby
insects hear will necessarily differ from the hearing of the superior

486

PHYSIOLOGY.

animals, and in reference to it we may possibly be allowed to surmise
that they do not possess the power of distinguishing tones ; but in oppo-
sition to this, it may be mentioned, that their females would not be able
to distinguish the luring tones of the males from any other sounds, and
consequently their possession of a means of indicating their presence
would not much serve them ; and also the signs of recognition among
the bees, to which we shall have occasion to return below, is opposed
to it. There are also other instances of a mode of communication among
insects, by means of peculiar sounds.

§ 278.

The way in which insects see by means of their eyes will be best
explained by Joh. Miiller’s investigations *. With respect to simple
eyes, we know, partly from their structure and partly by the direct
observations of Reaumur t and Hooke, who closed these simple eyes,
and then never detected the creatures moving in the direction of these
eyes, and that they only then flew whither their compound eyes could
survey their path, that these vertical points are actually eyes. Joh.
M idler has made it probable, from the structure of these eyes, that
their refraction must be very great, in as far as each ray of light suffers
a fourfold refraction, the first of which is produced by the convex
cornea, the second by the anterior convex surface of the lens, the third
by the posterior convex surface of the lens, and the fourth, lastly, by
the convex surface of the glassy body itself. This disposition presumes
an indistinct distant sight, as the object is thereby too great to be dis-
tinctly seen, but a well defined and distinct short sight. And, indeed,
we find in all the Arthrozoa , which have merely simple eyes, for
instance, in the Arachnodea, the power of sight agreeing with this
view, for it is only closely that spiders can see accurately, at a distance
the object appears to vanish from them. If we apply this to the simple
eyes of insects we shall find in them, likewise, that the function of their
simple eyes is adapted for a distinct close sight, and particularly for small
objects, which are difficult for the large field of vision of the compound
eyes to survey. They hence appear to make most use of their simple
eyes in narrow spaces, and as these simple eyes, as well as compound
eyes, are almost exclusively found in those insects which feed upon the

* Zur Vergleichenden Physiologie des Gesichtssinnes, p. 332, &c.

t M^moires pour servir ä l’Hist. des Insectes, tom. v, part i, p. 363.

OF SENSATION AND THE SENSES.

487

juices of flowers or other vegetable substances, they may probably be
of especial service to them for the discovery of this pabulum, parti-
cularly to those which thrust themselves into the flowers themselves,
and there seek the nectaries.

The compound eyes of insects appear constructed for vision at greater
distances, and to embrace a wider horizon, and yet by means of these
only are they enabled to have a distinct close sight. They are so
composed that each individual facet can survey but a small space of
the entire field of vision, so that each contributes to the perception of
all the objects comprised within that field ; but each separate one
does not at the same time see all such objects, whence the insect must
receive as many forms of objects in its eye as there are individual
facets to the eye. This consequence of a common and yet subsidiary
vision of these facets springs partly from the immobility of the eyes,
and partly it arises from the circumstance that only those rays of light
which fall in a right line upon a facet of the eye, which itself forms
the segment of a circle, can reach the optic nerve of this facet,
whereas all others are withheld by the pigment which partly sepa-
rates the individual glass lenses * from each other, and partly circu-
larly surrounds the margin of the crystalline lens beneath the cornea.
Hence it results that the nearer the object is, the more obliquely do all
but the perpendicular rays of light fall upon the facet, and therefore
contribute so much the less to the production of the image ; the object

* Treviranus, even in his latest work (Gesetze und Erscheinungen des Organischen
Lehens, neu dargestellt, vol. ii. Pt. 1, p. 77), denies the presence of this glass lens in the
eyes of all insects. Joh. Miiller has so far modified his earlier assertion that the Diptera
in lieu of it exhibit beneath the cornea a transparent crystalline layer, which beneath each
facet of the cornea stands in connexion with a filament of the optic nerve, but that in all
insects there is either a true crystalline lens or something analogous. According to
Treviranus, the lenses serve “ to shorten the distance of the concentrated rays from the
divisions of the cornea to the extreme ends of the filaments of the optic nerve, there where
the light, owing to these divisions, is but slightly refracted, and the refracted rays form a very
long arch.” But, according to Job. Miiller, their object appears to be rather to concentrate
into one point the rays falling in a right line — But the observation communicated by
Treviranus is more important, namely, that the filaments of the optic nerve proceed at first
from the clavate optic nerve itself in large stems, whence subsequently radiating branches
divaricate, as has been figured by Straus in the cockchafer (PI. IX. f. 6). In CEschna
forcipata he even saw the nerves run parallely to the plate which forms the inner circum-
ference of the eye, and thence” proceeded the filaments destined to supply the divisions of
the cornea.

488

1>HYSI0L0G¥.

consequently is most clearly seen closely, and more indistinctly at a
distance. If now each facet of the eye can survey but one small portion
of the field of vision, yet will the entire eye be able to survey a field
the larger in proportion to the size of the segment of the circle it forms
and to the convexity of its arch. Therefore, the larger the eye is, and
the more convex, the wider will be its horizon. The various structure
of the eyes of insects agrees also with this. Males, which are appointed
by nature to seek the female, have larger eyes than the latter. Insects
which live in and upon their pabulum itself, have small and flat eyes,
like all parasites ; others, again, which have greater difficulties to
contend with in procuring their food, as those insects which live upon
prey, like the Carabodea, Dytici, Libellula, &c., have either large or
greatly convex hemispherical eyes. The position of the eyes also
corresponds with their size and convexity ; flat eyes, which are able to
survey but a short space only, are always more approximate and placed
more anteriorly than laterally, and are frequently contiguous, as in the
male Syr phi. Spherical and very convex eyes are placed laterally, and
their axis is frequently directly opposite, but they yet harmonise by
their greater convexity with their field of vision, as is distinctly
observable in the large Carabi. But the fields of vision of the two
eyes do not affect each other, there still remains a free space between
the eyes, which the insect can only survey by turning its head.
Sometimes, to compass a still wider field of vision, a complete divarica-
tion from the usual form becomes necessary, as in Gyrinus , a division
of each eye, the one half of which lies upon the vertex, and the other
half is placed at the lower surface of the head ; the latter is for the
discovery of food which the insect finds in the water, and the former
to secure it from its enemies which approach out of the water ; or, as
in some male Ephemer ce, in which two large flat eyes lie upon the
vertex, and two smaller but more convex ones are found at the margin
of the head.

Joh. Miiller appends to his beautiful and apparently perfectly
successful explanation of the sight of insects, the result of which we
have condensed above, some other more general observations, which we
cannot forbear briefly introducing here. Thus the relative proportions
of the distinctness of the image in various eyes increases, according to
him, in proportion to the size of the sphere of which the surface of the
eye forms a segment, with the number and smallness of the facets, and
with the length of the transparent lens. Whereas the power of sight

OF SENSATION AND THE SENSES.

489

at a distance or close does not depend upon the structure of the eyes ;
every compound eye which distinctly discerns objects at a distance,
produces also closely a clear image of it. But the larger the individual
facets are, and the smaller the spheres formed by them, and the
brighter the pigment deposited between the lenses, the more indistinct
does the image of the object seen become, and in such a structure a
better image is formed of distant objects, but a worse one is seen of
approximate objects, for the rays are more diverging in consequence of
their proximity, whereas they run more parallely from every point of an
object at a distance ; in the former case, therefore, it passes through
the brighter pigment into the contiguous glass lenses, and renders
obscure the image that should be there formed upon the retina. — The
apparent size of the object seen corresponds only with its true size
when the convexity of the eye is perfectly spherical and concentrical
with the convexity of the optic nerve ; in every other case the apparent
size of the image will not correspond with its true size, and the image
must therefore appear distorted. Hence all elliptical or conically arched
eyes wil see worse than those forming the segment of a circle. — As
the structure of the eye does not differ in water insects and those
which avoid the light from that of day insects and those which live
upon the land, namely, the pigment is by no means brighter in the
former, as Marcel de Serres affirms, consequently their sight must fully
correspond with the sight of day insects.

With respect to the difference of structure of the eyes in larvae to
those of the perfect insect, in insects with an imperfect metamorphosis,
it consists especially in the relative size of their compound eyes. These
are always smaller in larvae, but continue increasing with every moult,
until they at last attain their full size. In the large eyes of the larvae
of the Cicada no facets are observed ; these, therefore, gradually dis-
tinctly develope themselves. The cornea of the eye is changed also
with the change of skin, which very well admits of a transformation.
Whereas simple eyes are never found in larvae with an imperfect
metamorphosis ; they present themselves only as bright spots where
they are subsequently to appear. — The majority of larvae of insects
with a perfect metamorphosis have merely simple eyes, and, indeed,
exactly where the compound eyes afterwards appear; many entirely
want eyes, and a few, as the larvae of the gnats, have already compound
eyes. With respect, therefore, to the development of the eyes during

490

PHYSIOLOGY*

the metamorphosis, it appears to take place especially during the
pupa state, and, indeed, by the compound eyes being gradually
developed from the simple ones. Pupae, however, have the entire
cornea immediately after stripping off their larva-skin ; and in the pupa
of Slratiomys Joh. Muller found beneath it the glass lens and the
layer of pigment yet but slightly coloured. If now this composition of
compound eyes from simple ones actually takes place, which cannot
very well be doubted, it may serve as a guide to the explanation of the
parts of the compound eye, which I would thus explain : the glass lens
corresponds with the glassy body, the lens with the thick cornea, and
this latter with a superficial thin layer of the entire cornea, which it
likewise is, and which is peeled off during the metamorphosis. After
the last moult this layer grows to the lens, and they then both appear
as identical, but, in relation to the other parts, merely as a thick layer
of the cornea. Hence the compound eyes of insects consist of the same
parts as the simple eyes.

SEVENTH CHAPTER.

THE LUMINOUSNESS OF INSECTS.

§ 279.

The peculiar light which many insects, but chiefly beetles, display,
is a very remarkable phenomenon. We have deferred its consideration
to the end of somatic physiology, as it does not appear to stand in direct
connexion with either of the four chief functions of the animal body,
but may be considered rather as the result of an entirely peculiar vital
phenomenon, the cause of which has been by no means thoroughly
ascertained. We will defer communicating the results of the experi-
ments made upon this highly interesting subject to the end of this
chapter, and first mention those insects in which this peculiar luminous-
ness has been observed.

The majority of them belong to the Coleoptera, and indeed to two
families which also in other respects present a tolerable affinity. These

OF THE LUMINOUSNESS OF INSECTS.

491

families are the Elaters and the Lamprodea . Among the Elaters we
know as luminous the E. noctilucus, E. ignitus, [ E. lampadion, E.
relrospiciens , E. lucidulus, E. lucernula , E. speculator, E. Janus,
E. pyrophanus, E. luminosus, E. lucens, E. exsiinctus , E. cucujus,
E. lucifer, and E. jihosphoreus *. In all of these there are two bright
oval, convex spots upon the thorax, which, after death, are of a greenish
yellow, and whence light, whilst living, streams forth, and in addition
to which there are two other spots upon the abdomen that are luminous,
and which, during repose, are concealed beneath the elytra. Indeed,
the whole inside of the body is luminous, but it is concealed by the
impenetrable integument, and only sometimes 'upon the very great
expansion of the abdomen is it perceptible through the divisions of the
segments. All the named species are found in tropical America, and,
according to Sloane, repose during day in dark shady places, and only
fly during dusk and at night, when they betray themselves by their
light ; but, according to Sieber, they also fly at noon in the sunshine,
but then exhibit no light. Their light is of a bright blue- white colour,
and in the larger species, for instance, in E. noctilucus t, it is so strong,
that, by its aid, small writing may be read at night if the luminous
spots be passed regularly over the lines. Some naturalists who have
had the opportunity of observing the insect in its native country (Spix)
assert that they have found beneath the luminous spots a yellowish
glandular mass, to which a multitude of branches of the tracheae are
distributed from the approximate main stems. These are the true
luminous bodies whence the light streams forth either brightly or dully,
according to the quantity of air the insect admits to them by respiration.
It is also said that the insect can prevent the emission of all light by,
according to Spix, preventing the admission of any air. Amongst the
natives, all these insects are called Cucujos or Cucujii ; they use them
as ornaments for their dresses by night, and they are worn by the
females especially as ornaments to the head-dress, and the Indians are
said to bind them to their feet on a journey, to enable them to discern
their road more distinctly. According to Piedro Martire the
inhabitants of Saint Domingo keep the luminous Elaters in their rooms

* See Illiger in the Magazin der Geselsch. naturf. Freunde zu Berlin, vol. i. p. 14.

+ See Curtis in Zoological Journal, 1827, No. 2, p. 379. Heusinger Zeitschrift, vol. iii.
Pt. 1, p. 137. — Thons Archiv, vol. ii. Pt. 2, p. 63.

I In Kirby and Spence, vol. ii. p. 462.

492

PHYSIOLOGY.

at night, which destroy the gnats that would otherwise disturb persons
sleeping ; but this tale does not merit belief, as the Elaters are well
known not to be carnivorous, but feed upon nectar and pollen. Yet
by the light they distribute they may probably chase away the gnats.

§ 280.

The European Lampyri were known as luminous earlier than the
Elaters. The ancients were acquainted with this faculty*. The
Romans called them cicindelce , the Greeks Xafnrvptdes ; but it does not
appear that they distinguished several species ; and, as in southern
Europe, the ^ Lamp. Italica is the luminous species, it is doubtlessly
upon this that they made their observations. Besides this, there are
three other species in Europe, L. nocliluca, L. splendidula, and
L hemiptera, the second of which is common with us (Germany), the
first is found in more northern countries, and the third in southern
ones. The last is not deficient in the phosphoric light, as Illiger first
thought, and, probably, it is also present in the numerous extra-
European species of this genus. The most recent experiments upon
their luminousness have been made chiefly upon the L. noctiluca, which
is common in the south of England and in Sweden, by J. Murray f ;
upon L. splendidula by Macartney | and Macaire§ ; and upon L. Italica
by Carus ||. L. hemiptera was observed and described in detail by
Muller IT, and he also first discovered its luminousness, although the
light was but feeble. Both sexes are luminous, as also are the Elaters ,
but the light is strongest in the female. In the Lampyri it does not
stream from the thorax, but from the posterior extremity of the abdomen,
where also, even after death, there are spots which are brighter than
the rest of the integument, and it is these especially which shine.
Besides the difference of light in the two sexes, there are others
between them even in their external form. In L. noctiluca , the largest
of the European species, the male, which has wings and elytra, is of a
uniform brownish grey, with a reddish grey margin to the pronotum :
the apterous female has a similarly shaped back, which is, however, of

* Plinii Hist. Nat. Lib. 18. c. 66. 2. — Aristot. Hist. An. 1. 3.

-f* Experimental Researches, Glasgow, 1826.

$ Schweigger’s Jour. &c. vol. x. p. 409 Gilbert’s Annal. vol. Ixi. p. 113.

§ Gilbert’s Annal. vol. lxx. p. 265.

|| Analekten zur Naturw. u Heilkunde, p. 169.

H Illiger ’s Magazin, vol. iv. p. 175, &c.

OP THE LUMTNOUSNESS OP INSECTS.

493

but one colour, and it has a yellow-white, thin-skinned fat abdomen.
In both, the luminous spots present themselves as four bright points,
two of which are upon the antepenultimate abdominal segment, ad
two upon the next one. In the smaller L. splendidula , the male, which
is also winged, and is of a brown grey, has a bright glassy spot upon
the convex margin of the pronotum : the female, which is entirely of a
whitish yellow, and is brown only on the centre of the pronotum, has very
short oval elytra, which merely cover the margin of the mesonotum, but
it has no wings. In both the luminous parts are two transverse bands
on the ventral side of the two penultimate abdominal segments, yet in
the female the whole abdomen distributes but a weak light. With
respect to size, L. Italica is between both ; it is black, with a red prothorax
and legs ; two large white spots on the penultimate and antepenultimate
abdominal segments display the light. In this species the female does
not differ externally from the male ; both are winged ; yet some ento-
mologists, as Rossi, Illiger, Carus, speak of apterous females, but they
have certainly mistaken the larva for the female *. In L. hemiptera ,
the male has truncated elytra and the female none. It is also the
smallest of all, being scarcely four lines in length, entirely of an opaque
black, but which is lighter in the female, and the ventral plates of the
penultimate and antepenultimate abdominal segments are whitish. But
these do not emit the light, which is confined to two round spots on
the penultimate segment. In L. splendidula , I have discovered the
larvae to be luminous. Müller was acquainted with the larva of
L. hemiptera , but he does not say whether it gives light. The
L. splendidula, noctiluca and Italica conceal themselves during the day,
and only appear at night-fall, when, upon warm damp evenings, the
male flies about, whereas the female sits tranquilly among the hedges
and shrubs, betraying her situation to the male by her much brighter
light. L. hemiptera creeps about also by day, but generally in damp
weather ; it also appears earlier in the year, namely, towards the end
of April, whereas L. splendidula about the end of May and the begin-
ning of June, and L. noctiluca, on the contrary, is found chiefly towards
the end of the summer.

Their light is of a bluish white, and sometimes also of a greenish

■ * Touss. de Charpentier, Horae Entomologicae, p. 192. PI. VI. f. 5 and 6. He also

separates the larger specimens, as L. Lusitanica , and the smaller ones with a black spot
upon the pronotum are, according to him, the true L. Italica.

494

PHYSIOLOGY.

or quite bright colour ; it is strongest in the female, and shines uni-
formly, as in L. noctiluca and L. splendidula, but in L. Italica and in
others * it varies in intensity in rhythmical vibrations ; during the
day it is not observed, and can be momentarily suppressed by night
at the will of the insect. This they appear to do in moments of
danger, at least I have often observed that those which I have caught with
my hat during flight immediately ceased shining, and so frequently
deceived me by my fancying that I had missed the creature, but I
afterwards discovered it in my hat, when it again shone. The light is
increased during motion as well as during exciting corporeal action, for
instance, during copulation and in great heat, but which must not be
much higher than 40° R. ; cold, however, speedily destroys the faculty,
and even at 10° beneath zero. If the insect be kept some days in the
dark it entirely loses its luminousness, but regans it upon being again
placed in the sunshine. After its death the light still lasts some hours
and even days, and even afterwards can be re-produced by warm water
or acids. All poisonous gases, which speedily kill the insect, destroy
just as quickly its light ; even in pure oxygen the light was indeed at
first brighter, but disappeared at the death of the insect. In heated
water, on the contrary, the light long continued in a temperature
not exceeding 50° R., but immediately disappeared upon the applica-
tion of greater heat, and also by degrees as the water cooled. Elec-
tricity has no influence upon the strength of the light, nor did it
produce any luminousness in insects already dead, whereas galvanic
electricity occasioned a much brighter light, and even re-produced the
luminousness in dead insects which no longer exhibited it. But these
effects are not produced in vacuum, nor if the creature be covered with
oil. Upon anatomical inspection there was found at the shining spots
a whitish, transparent, granulated mass, intersected by tracheae, and
which mass did not appear to be very different from the fatty substance.
This mass shines also for a time when removed from the body of the
insect, particularly in warm water, but it loses its light upon drying,
but regains it for a short time upon being remoistened.

Among other beetles we find the Scarabeus phosphoreus named as
luminous, and upon which Liice has communicated some observations +.

* See Cams, at the above cited place, and in the Isis, 1824, vol. ii, p. 245, where it is
related, that according to Long, a New Holland species also exhibits this rhythmical
luminousness.

t Rozier, Journ. de Phys. vol. xliv. p. 300.

OF THE LUMINOUSNESS OF INSECTS.

495

According to him, the insect which is found in the department du Var,
in the vicinity of Grosse, in May and June, but which, with respect to
its situation in the system, is no farther known, distributes a phosphoric
light from its abdomen, that disappears when the beetle contracts it,
but which remains with the juices pressed from the creature so long as
they continue moist. Paussus splicer ocerus also, which is found on the
coast of Guinea, and is remarkable for the singular globular form of
its antennae, its discoverer, Afzelius, observed likewise to emit a weak
phosphoric light from the globe of the antennae * ; the same is supposed
of Chiroscelis bifenestrata, Lam., a beetle belonging to the family of the
Melanosoma , which is provided with two oval, hairy, reddish spots
upon its second ventral segment, and it is from these that the light
issues f. From a communication of Latreille $ the large yellow spot
is luminous upon the elytra of Buprestis ocellata, a very beautiful
insect, native of China.

§ 281.

Instances of luminous insects not of the class of beetles are great
rarities. Kirby and Spence observe that it is to be seen sometimes in
the eyes of some nocturnal Lepidoptera, for instance, in Noclua psoi
and Cossus ligniperda, and also relates an instance in which the com-
mon mole cricket ( Acheta Gryllotalpa, Fab.) is said to have been
luminous ; but this faculty can present itself merely as an exception,
for no other observations have ever been made upon it. Perhaps they
had been in contact with rotten wood, which is also sometimes luminous,
or with other rotting substances, and the light with a portion of the
substance still adhered to them. The luminousness of the Brazilian
lantern-fly appears more credible, from the positive assertion of Mad.
Merian§. In this insect, which belongs to the family of the Cicada
among the Hemiptera , the light is said to be produced from the large
clavate frontal process, and to be so strong that a single specimen is
sufficient to admit of reading very clearly by it in the dark. But this
observation is not supported by the testimony of any modern traveller.
Count Hoffmannsegg, supported by the communications of Sieber, was
the first to attack as groundless this tale of Mad. Merian ||, and subse-

* Trans. Lin. Soc. vol. iv. p. 261. f Ann. du Mus. d’Hist. Nat. No. XVI. xxii. 2.

X Kirby and Spence, vol. ii. p. 471 .

§ Mar. S. Merian de Generat. et Metam. Insect. Surinamensium, p. 49.

|| Magaz. der Gesellsch. Naturforsch, Freund Izu. Berlin, vol. i, p. 153.

496

PH VSIOLOGY.

quently the Prince of Neuwied * confirmed this contradiction, having
never observed the least trace of a peculiar light in the Fulgora later -
naria. Fab., which is by no means a rare Cicada in the Brazils.

§ 282.

These, therefore, are the collective instances hitherto known of a
peculiar light emitted by insects. There are many opinions of the
causes which produce this faculty, one of which lays most stress upon
the influence of the nervous system, another upon the respiration, and
a third upon the circulation. Others, but chiefly chemists, speak of a
substance resembling phosphorus secreted by peculiar organs, and
whence the light is emitted. Treviranus, however, who has anatomi-
cally inspected Elater noctilucuSj as well as the Lampyri, say there is no
organ anywhere situated that secretes the luminous substance, not even
at the luminous spots, and that this quality proceeds from the fatty
substance. This appears, as is confirmed by Macaire’s investigations,
to consist, in luminous insects, of a great portion of albumen, and to
this some ascribe the faculty of being luminous, but it requires the
peculiar quality, according to Maeaire, of being semi-transparent. We
know no instance of albumen itself being luminous, but must conclude
that some other substance is incorporated with it, and that either this
substance alone, or by its connexion with the albumen, is the cause of
the light produced. The best known substance that produces light
is phosphorus, which is abundantly present in animal bodies, and we
therefore might ascribe the luminousness of insects to the phosphorus
intermixed with their fatty substance. Phosphorus alone does not
shine, but only gas charged with phosphoric vapour when coming into
contact with oxygen, or if this be the saturated gas when this meets
with hydrogen or azote, and this kind of mixture is only to be exhibited
in luminous insects to explain the faculty peculiar to them. This,
therefore, admitted, for a convincing proof of its presence has not yet
been produced, it follows, as Treviranus accurately says, and observa-
tion has confirmed, that the insect is luminous not merely at its brightly
coloured spots, but throughout its interior j- wherever the luminous
phosphoric combination is found; the brighter coloured or rather
colourless spots, for the subjacent fatty substance is the cause of the
whitish yellow colour, serve only to give a free passage to the light.

* Reise nach Brasilien, vol. ii, p. 111.

t See Treviranus, Biologie, vol. v. p. 475.

OF THE LUMINOUSNESS OF INSECTS. 497

The observations that have been made under a variety of circumstances
also tolerably harmonise with the conditions under which phosphorus
is luminous, in so far as its light disappears in irrespirable gases,
increases by warmth, but is destroyed, also like phosphorus, bv cold,
immersion in oil, alcohol, acids, saturated solutions of salts and alkalis,
as also in vacuo.

If, therefore, phosphorus appears to be the substance which produces
the light in insects, it may be. asked, as phosphorus is not luminous in
itself, what may be the conditions under which phosphorus is luminous?
To this the above remarked differences of opinion especially refer.
As phosphorus can only become luminous by contact with oxygen, if,
therefore, we imagine it combined with the fatty substance, or with
its albumen, respiration gives it luminousness ; by means of respiration
oxygen is deposited in the corporeal substance, and each inspiration
therefore makes the beetle shine. Now, as we have before noticed,
respiration being strongest during flight, it necessarily follows that the
emission of light will also then be most powerful. In opposition to
this the wingless state of the female might be urged, yet her short
thicker body must contain more of the fatty substance, and must there-
fore emit a stronger light than that of the male. Next to respiration
the circulation of the blood appears to have considerable influence upon
the light, for we know that the substance emits the light only when
moist. As, now, the blood flows all round upon the fatty substance,
this may be considered as the moisture, which helps to support the
luminousness. Carus has also observed that upon each pulsation, and
consequently upon each fresh wave of blood, the light shines brighter.
He refers to this also the brighter shining of the female, as she con-
stantly dwells in dark, damp places. Thirdly, the nervous system may
exercise a certain influence upon the production of the light, for as it
is the chief agent of all the voluntary actions of the body, it will also
necessarily exercise an influence upon the voluntary suppression of the
light if the insect stops this influence by checking respiration in the
. way in which it causes the nerve to act upon the muscle in muscular
motion. That it possesses this faculty of checking the respiration we
know, but that this cannot be long protracted lies in the very nature
of the thing, and thus by both causes the momentary cessation of light
which is frequently observed, and which we have mentioned before,
may be produced. Upon respiring anew the beetle would necessarily
become again luminous.

K K

498

SECOND SUBSECTION.

PSYCHOLOGICAL PHYSIOLOGY.

§ 283.

After the consideration of the corporeal functions of insects there
still remains a whole series of phenomena which are not the pure
results thereof, but are superior intellectual functions, which may be
exercised apparently at the will of the insect. Similar phenomena
naturalists have observed, not in insects only but likewise in the higher
animals, and in them very especially, and have found therein the
analogies of the intellectual powers of man, yet with the essential
difference that these phenomena in animals must necessarily ensue,
whereas man, superior to the compulsion of nature, has the means of
resisting this necessity by his volition. Hence the idea of freedom.
Were the enjoyment of this freedom, and indeed especially of moral
freedom, — for external freedom is merely the result of internal or moral
freedom, — given to man by nature with restrictions, his intellectual
superiority would then completely vanish, as he would then necessarily
exercise all his functions within certain limitations, and never remain
within these limits nor ever surpass them. His freedom then would
also be merely apparent, and he, as well as all animals, would then be
curbed by the chain of certain instincts, the satisfying of which would
become a necessity. But man is free, that is to say, he has the faculty
of in so far subjecting his natural instincts to other relations, either
voluntary on his part, or introduced by social life, as the law of self
preservation will admit, and may satisfy them at his own discre-
tion ; whereas the animal is not free, it exercises all, both corporeal
and intellectual functions, from a determinate necessity, from which it
has not the power of emancipating itself. Thence the entire greatness
of man consists in his freedom, and in it consists the faculty of his
progressive development or perfection, as well as the possibility of his
degeneration, and which would place him beneath the animal. The

INSTINCT.

499

animal is equally perfect in all its individuals; men are distinguished
from each other as perfect or imperfect, according to the exercise of
their freedom towards good or evil.

§ 284.

The phenomena thus characterised bear in animals the general name
of instinctive impulses, and that which urges their exercise we call
instinct ; in man we call them intellectual phenomena, and their
stimulant mind or soul. Instinct in animals, therefore, is the ana-
logue of the soul in man ; a soul differing only from the human soul
by the necessity with which it does everything, whereas the human
soul is independent of necessity, and freely resolves upon its actions.
From this necessity, with which the instinctive impulses of animals
act, ensues their determinate restriction in every species. The instinct
of every animal is enclosed within a circle, which it cannot pass, and
all the phenomena within this circle are repeated by every individual
in the same manner. In them, therefore, there is no teaching or pro-
gressive perfection, but the young just born individual exercises all its
instincts just as its mother did, without being in the least taught to do
so. This unconscious execution of the first occupations harmonises with
the desire of the infant for the mother’s breast, and with its innate
power of suction, that we cannot forbear considering both as quite ana-
logous phenomena. But it is only during his nonage that man exhibits
himself as an animal with innate skill ; these disappear so soon as he
becomes older and more developed, whereas they remain with the
animal during its whole life. The celebrated wisdom of many animals
is founded solely upon the faculty by necessity present in them, and
what we admire is nothing more than the general law of nature, that
for the attainment of their object they always select the best and most
serviceable means. Necessity and suitableness are therefore as inse-
parable phenomena in the instinctive functions of animals as in the
physical world are the ideas of life and action ; they cannot be parted,
one conditionates the other ; for a necessary unsuitableness would
destroy itself, whilst man, by the insight gained through experience
and custom, is led to new endeavours, upon an ascertained unsuitable-
ness, which at last conducts to the suitable accomplishment of his
object. But the animal makes no essay, what it undertakes it suc-
ceeds in, and indeed with the least trouble, and with the least expense
of force, as it seeks the easiest and surest way to its object. Yet this

k k 2

500

PSYCHOLOGICAL PHYSIOLOGY,

apparent choice is no choice, but iron necessity, which rules the life of
all organisms, and which endeavours to dominate in the life of man,
wherein it at first indeed acts promotive, but subsequently chiefly
obstructive and restrictive.

§ 285.

But we, nevertheless, observe phenomena in many animals, and also
in insects, which appear to be the result of a free and rational consi-
deration, and of a certain degree of reflection ; indeed experience,
recollection, and memory are likewise perceived in them.

The reflection of insects consists in the choice of the best means to
attain the object. There is nothing remarkable or astounding in this
when we admit that nature for the exercise of every function of the
insect has prescribed to it the way, and that we therefore observe all
insects invariably follow this prescribed path. But there are facts
which cannot be made to harmonise with this prescribed course. For
instance, it is well known that when bees in the construction of their
combs meet with objects that obstruct their progress in a right line, they
avoid them by the change of its direction, before the comb touches the
object, therefore by the immediate cessation of the continuation of the
work in that direction. Darwin observed a sand-wasp ( Sphex sabulosa )
which wished to carry off a large fly that it had caught, but as it
violently fluttered with its wings, and so hindered her own progress,
she bit off its wings, and then flew off with it unimpeded. We must
in these cases, — as in the organs of the body and their functions there is
exhibited a certain faculty of adaptation to a determinate purpose, as, for
example, the alternating secretion of one instead of the other, of the
intestine instead of the skin, in rheumatic affections, &c., — admit also of
an adaptation of the instinct to new purposes, which expresses itself in
the recognition of the necessity of a change of the function yet in action
before the obstruction which obligates it absolutely obtrudes. It is
evident that this recognition is a purely intellectual activity, which
appears to contradict the prescribed necessity in the functions of
animals. But this contradiction is only apparent, for nature has also
prescribed the choice of the most serviceable means to the end, and
this choice presumes a knowledge of difficulties and hindrances. Hence
the instinct of the animal is competent to a partial quitting of the
prescribed circle as soon as extraneous phenomena intrude into the
actions of insects, which likewise lie beyond the circle of their usual

INSTINCT.

501

functions, and this transit, this voluntary adaptation, still more convinces
us that the instinct of animals corresponds to the soul of man, and that
reason, which has been considered as the exclusive characteristic of man,
is not wholly wanting in them.

The proof that insects acquire a certain experience, and are capable
of combinations of what they have experienced, many bees exhibit to
us, which lick with their long tongues the honey glands of flowers, and
fly industriously around from one to the other. Thus, humble-bees,
which cannot reach with their proboscis the nectaries placed at the
bottom of the long tubular flower, open it at the side with their
mandibles, and now passing their tongue through the aperture, imbibe
the honey previously inaccessible to them. According to Ch. K.
Sprengel, those flowers which contain nectaries are often decorated
with radiating markings, generally red, which serve the insect as a
mark of recognition. If such a recognition actually take place,
experience which the insects have gained can be the sole instructor.
According to Reaumur, the ants that have formed a dwelling in the
vicinity of a bee-hive never enter it so long as it continues occupied by
the bees, but laboriously collect their nectar from the aphides dispersed
upon plants ; but if a hive, of which the bees have been destroyed, be
placed in the situation of the former one, they speledily visit it in large
troops, and enjoy the honey undisturbed. Here, therefore, we again
detect experience, viz. that the bees immediately destroy all visiters
that intrude into their dwelling, as the warning instructress of the
cautious reserve of the ants.

To the faculty of collecting experience, a second is superadded,
which gives this experience its value, namely, memory. The experience
gained must remain in constant recollection if it be to yield a constant
advantage, and it is made so by a quality of the soul which we call
memory. This quality is also attributable to the instincts of insects.
The same as the swallow and the stork yearly return to their former
dwellings, so does the bee each spring revisit her former collecting
places, and the very same tree whence she gathered honey the preceding
year. Among the many hives which may possibly be placed together,
each bee accurately recognises her own when she returns from her
journeys, and we never observe the neuters flying around other hives
for the purpose of discovering theirs. This is not a mere recognition
of the same hive from its external marks, but the bee exactly knows the
spot where it is to be found, for if another have been put in its place,
it will prepare within it, in conjunction with all its returning com-

*502

PSYCHOLOGICAL PHYSIOLOGY.

rades, a new dwelling, supposing that the preceding one has been lost
in the interim *. Kirby and Spence relate another still more striking
instance of the memory of these creatures, in which a swarm from an
old hive occupied a hole in the roof of a house, but were again removed
by its possessor. Every year the envoys of the new swarms of the same
hive regularly returned to this hole to convince themselves of its
existence and suitableness, certainly a distinct proof of the remem-
brance of the discovered place among the older members of the hive.
There are many instances of the memory of insects, which all, more or
less, prove it to be a quality of their instinct. Thus, the Odyneri ,
which have found a hole for the dwelling-place of their young, con-
stantly return back exactly to it when they quit it to fetch the young
ones’ provisions. If it be closed during their absence, on their return
they seek about upon the wall, yet without entering other holes ; if
they again find it, they remove the obstacles and pursue their previous
labours.

But the power of communicating to their comrades what they
purpose is peculiar to insects. Much has been talked of the so-called
signs of recognition in bees, which is said to consist in recognising their
comrades of the same hive by means of peculiar signs. This sign serves
to prevent any strange bee from intruding into the same hive without
being immediately detected and killed. It however sometimes happens
that several hives have the same signs, when their several members rob
each other with impunity. In these cases the bees whose hive suffers
most alter their signs, and then can immediately detect the enemy.
But in what these signs consist is not known. The wasps also apprise
their comrades of the place whence they fetch the materials of their
nests, whence it happens that some always fetch the same material, for
example, rotten wood ; others a different material ; and others, again,
coloured substances. — The ants, also, can inform their own citizens of
the presence of a choice morsel, for Kirby and Spence relate an instance
where a pot filled with treacle was suspended from a ceiling, and which
being discovered by one, she fetched a whole host of her comrades. In
places distant from their abode, ants touch each other with their
antennae, so to recognise their friends and enemies, and, after having
satisfied themselves, they pursue their journey. A remarkable instance
of such a communication is related in Illiger’s Magazine J, in which a

* Kirby and Spence, Introduction, vol. ii. p. 590.

*f- Germar’s Magazin, vol. iii. p. 425. f Vol. i. p. 488.

INSTINCT,

503

traveller observed Gymnopleurus pilularius prepare its ball of dung.
Th is ball happened by accident to fall into a hole whence the insect
could not remove it by all its exertions. Tt therefore apparently gave
it up, but speedily returned with three comrades, and their united
labours succeeded in accomplishing it. This instance is so remarkable,
that we might be inclined to doubt its veracity were it solitary, but
those above communicated are so analogous, that we cannot help consi-
dering it as true. They therefore prove that insects possess the power of
communicating their objects to their fellows without the intervention
of language, and that the imparting of determined objects must be
classed with the qualities of insect instinct. We have thus found four
important functions which are considered as the qualities of the human
soul to exist even in insects.

§ 286.

If we now survey the several phases of the instinct of insects, we
shall find that all refer either to the preservation of the individual or
to the conservation of the species, and, consequently, stand in close
connexion either with the several functions of insects, to provide
themselves with subsistence, or with the suitable depositing of their
eggs, the provision of their young, and their undisturbed development,
&c. Between these two groups other phenomena present themselves
which refer to both, we mean their connexion in large societies, which
is peculiar to certain species, and which precisely furnish us with the
most animated and comprehensive picture of the several intellectual
activities of which insects are capable. We will, therefore, more closely
inspect these chief functions of the instinct of insects, and, in the first
place, those referring to self-preservation ; then those referable to the
conservation of the species ; and, lastly, the societies and unions which
have been observed in certain genera and species.

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PSYCHOLOGICAL PHYSIOLOGY.

EIGHTH CHAPTER.

OF THEIR SELF-PRESERVATION.

§ 287.

The means which insects make use of for self-preservation are of
two kinds, as they refer to their mode of procuring food and to their
means of defence against their enemies. They both evince in so many
instances an amount of sagacity, that we feel astonished at the apparent
liigh degree of reflection and consideration announced by it ; indeed
they would absolutely convince us of a freer activity of the mind, did
not the same phenomena of necessity and a want of freedom exhibit
itself in as far as that every individual repeats the same processes in
the same manner and in perfect concordance even to their minutest
details, without having learnt it from its predecessors.

I. Means of Defence.

§ 288.

The means insects have received from nature for their defence may
also be viewed under two aspects, namely, first, as a passive means
derived from the form and structure of their bodies, and, secondly, as
an active means of defence derived from the free exertion of strength on
the part of the insect.

Passive means of defence are derived chiefly from the form and
colour of the body, by their giving insects such a resemblance to the
objects in or upon which they dwell, that upon superficial observation
it is not easy to distinguish them from it. To give examples of this,
we might remind our readers of the similarity of colour of many beetles
to the ground upon which they are found. This is strongly exemplified
in the large family of Curculios, in which the majority of the species
of the genera Thylacites , Sitona, T r achy phi ceus, Cleonis , &c. are of an
earthy grey or yellowish, like the sand or loamy soil where they creep.
Thylacites incanus is of a brownish yellow, like that of the colour of
the earth of the woods covered with fallen pine leaves. Thylacites

SELF-PRESERVATION.

505

geminatus , in many districts a very injurious enemy to young vines*
is of the same yellowish brown grey colour as the soil of vineyards.
Cleoiiis sulcirostris, Cl. glauca , Cl. marmoraia, &c.* are greyish, like
the dry light earth upon which they crawl. The resemblance is still
more striking in those beetles which dwell upon a slippery clay soil*
and which from their rough integument are unwillingly soiled with
this clay* as, for instance, Asida grisea , Brachycerus algirus , Meleus
variolosus, Trox arenarius , Opalrum sabulosum , and many others.
Others, again, like our native tortoise-beetles ( Cassidea ) are generally
of the bright green colour of the plant upon which they dwell.
But the resemblance of insects in other orders to lifeless things is still
more remarkable, namely, in the Orthoptera, in which many species of
the genus Mantis resemble fallen and green leaves, both in form and
colour, as Mantis siccifolia, M. oratoria, M. phyllodes , &c. The
locusts also, which dwell chiefly amongst high grass and upon green
plants, are usually of a bright grass green ; others, as L. Ephippium
and the Grylli, which prefer dry hedges and fields, are, like these, of a
grey streaky colour and sculpture. This is also the case with many
bugs, which, as they are deprived of all other means of defence, would
necessarily become the easy prey of all enemies if they did not, as in
the species of the genus Aradus , resemble the bark of trees where they
dwell, or were they not, like the Corel , difficult to discern upon fields and
hedges where they are found, from their grey colour. The same means
of defence is possessed by many of the moths which, as it is well known*
repose tranquilly during the day, and only fly at dusk. Many conceal
themselves in the slits of the bark, and, consequently, from their con-
formity of colour, are easily overlooked. The caterpillars also of many
Lepidoptera possess in their form and colour means to prevent their
being observed, many of them being green, like the leaves upon which
they live. Others, namely, the Geometers, so closely resemble the young
twigs of trees, that even upon a strict inspection they are difficult to be
recognised as caterpillars, particularly if they, as they not unusually do,
stretch themselves straight out, holding only by their posterior legs,
when they perfectly resemble a young leafless twig. I was myself once
thus deceived by the caterpillar of Ph. quercinaria, Borkh ( Eunomus
Erosaria, Tr.), mistaking it for a small dry twig, upon wishing to
break off a small twig of oak, but I subsequently observed its motion*
and then, upon a closer inspection, recognised it as the caterpillar of

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PSYCHOLOGICAL PHYSIOLOGY.

this moth. The caterpillars also of Gastrophaga quercifolia, of Cato-
cala Fraxini , O. &c., very much resemble the dry twigs of trees, and the
moth of the first also closely resembles a dry fallen leaf, and may thus
easily conceal itself when it reposes motionless by day, as is the case
with most moths.

As, in all the above instances, form and colour are the means of
defence, in others, it is provided by the external integument and
peculiar habits. Thus the caterpillars of most of the butterflies and
the larvae of the tortoise-beetles have a skin covered with simple or
ramose spines, which clothing gives them a formidable appearance, and
thereby partly, and partly by the pain which the spines give to the
oesophagus, disqualify them for being the food of birds. Others are
protected by their thick hairy clothing both against the prejudicial
influences of the elements as well as from the attacks of insectivorous
birds. The cuckoo alone, which likewise, from its other habits, is a
most remarkable bird, not deterred by this fur from swallowing such
caterpillars, and it is thence that its stomach is frequently covered
inside with hair, an occurrence that has occasioned much dispute, as
some naturalists maintain that this accidental clothing is the constant
structure of the stomach. Among the habits which many insects find
a protection from their enemies, we include that of many larvae covering
themselves with their own excrement, as is the case with the larva of
Lerma merdigera and some others. They then resemble little lumps
of dirt, and are certainly also regarded as such by many of the enemies
of insects.

Other insects secrete peculiar fluids, in which they partly envelope
themselves and partly thereby secure themselves from the attacks of
their enemies. The Aphrophora spumaria is one of these, which
envelopes itself in a thick white frothy fluid, that comes out of the
anus. This cuckoo-spittle is found during summer upon almost all
shrubs, and particularly willows ; within it is seated the larva of that
Cicada , which undisturbedly sucks its nutriment from the plant, con-
stantly the while secreting fresh bubbles. The perfect-winged insect
has no longer the frothy covering. We find other coverings in the
Aphidce and tortoise-beetles, which envelope themselves with a white
woolly or fibrous substance, the origin of which we are not yet
acquainted with, but it appears likewise to be produced by a peculiar
secretion of the skin. Other insects, as the Cant har id es, burying-

SE LF-FFiE SE It VAT ION .

507

beetles, carrion -beetles, carrion-flies, wasps, &c., emit, upon being
touched, such a nauseous stench, that this must prevent every insectivo-
rous bird from using them as food.

Another peculiarity which may be also classed among the passive
means of defence is their tenacity of life, and for which they have to
thank, in the first place, an organisation adapted to all possible circum-
stances, and, secondly, their hard exterior integument. The latter
acquires in many insects, particularly the beetles, such hardness, that
it is with difficulty that their elytra can be pierced. This is especially
the case with the large Curculios , for instance, the species of the genus
Cleonis , Lixus , Otiorhynchus, &c., then in the Hisiers, which have
so firm an integument, that, upon any but a stony surface, they may
be trod on with impunity, and are more easily pressed into the ground
than crushed. This is partly the case also with the Byrrhi. This
hard clothing is not found exclusively among the beetles ; in the
otherwise soft Diptera there is an instance of the kind, namely, in the
louse-fly of the sheep ( Melophagus ovinus ), which cannot be crushed
between the fingers ; and the smaller parasites, as the louse and the
flea, are difficult to crush in this manner. Respecting the tenacity of
life with which they, even wounded or mutilated, resist death, we have
before cited instances. Impaled insects will live thus for several wreeks,
and at last appear to die less from the effect of the injury than from
hunger. I myself have kept Blaps mortisaga for three months without
food ; and Rudolphi mentions, in his “ Physiology,” an instance which
Schüppel communicated to him, of an. insect of the same family which
this skilful entomologist received from the South of France, which,
although impaled, arrived alive in Berlin, atid here even continued still
to live for some time. Other cases, in which beetles have been enclosed
in wood for years without any food, have been communicated by other
writers ; and instances of insects remaining torpid in spirits of wine
for several hours, and indeed days, and yet be re-aroused from their
sleep upon being brought into the air, I have previously mentioned.
They still longer retain their life in water. According to Lyonet, the
caterpillar of Cossus ligniperda will live nearly three weeks beneath
water ; and according to Curtis, the plant lice will survive for sixteen
hours in that element, but die if continued for twenty-four. Kirby
and Spence relate, after Reeve, instances in which in warm foun-
tains, the temperature of which was about 205° Fahr., he has found the
larvae of Tipidcc ; and Good has observed little black beetles, probably

508

PSYCHOLOGICAL PHYSIOLOGY.

Colymbetes , in the hot sulphur baths of Albano, and which died when,
placed in cold water. He himself found a specimen of Lyctus Juglctndis
Fab., in the warm dung of a hotbed, and cast it into hot water to kill
it ; after it had been some time there it was removed, and appeared
dead, but speedily again moved, and entirely recovered. Reaumur and
De Geer also relate instances of the larvae of the gnats being found
frozen in ice, and which revived when the ice melted. One of my
acquaintances saw a Dyticus latissimus enclosed in ice, he took it out,
and found it alive ; and Alex. v. Humboldt found insects upon the
Cordilleras above the limits of snow, which, although not natives of this
altitude, yet retained their vivacity at this temperature.

§ 289.

The active means of defence which we find in insects are more
numerous and more striking to the eyes. Some appear merely defen-
sive, in as far as insects which use them can only protect themselves by
attitude and appearance : among them we class the sudden torpidity
aped by many insects in a moment of danger. Thus the minute Aga-
thidia roll themselves up, and appear dead ; thus the Byrrhi and
Anobia contract their limbs, and pretend death so long as they are in
the hands of their enemies. Others stretch out their limbs, as Geo -
trupes siercorarius, and thus imitate dead insects. Among the Hy-
inenoptera the ruby-tails ( Chrysodea ) adopt the first plan of deceiving
their enemies, by rolling themselves up when caught, and only arouse
themselves upon the departure of their enemy. Others, particularly
the tortoise beetles and Curculios , endeavour to secure themselves upon
the approach of an enemy by suddenly falling down from the leaves
upon which they were seated, that they may thus conceal themselves
among the leaves and blades of grass ; if they are found here they si-
mulate death, but not with the obstinacy of the species of the preceding
genera. Those active means of defence which may likewise be used as
defensive weapons are very numerous, and partly consist in large man-
dibles and other pinching instruments, and partly in concealed stings.
All the carnivorous beetles are furnished with the first kind of arms,
namely, the Carabi, Cicindelce , Dytici, Staphylini , &c. In general,
however, the bite of these creatures is not injurious, and with the
exception of the pain occasioned by the mechanical injury, the bite has
no prejudicial consequences. Among the vegetable feeders also there
are many, as the Dynastes , Lucanus Cervus , 'many capricorn beetles.

SELF-PRESERVATION .

509

and others, furnished, some with really large mandibles and others with
processes upon the head and prothorax, whieh, like the mandibles, caii
meet like tongs, and thus serve as a weapon. This is asserted of the
Hercules and its large comrades. Pincers of a different kind, as in the
earwig, are likewise doubtlessly arms, but in general their possessors
are too weak to wound the larger animals or man with them. The
generally known means of defence of the bomb-beetle ( Brachynus
crepitans) is of a peculiar description : it consists in its ejecting from
its anus against its enemy a vapoury moisture accompanied by a slight
sound, and which vapour has great resemblance to the gas of aquafortis.
It is not yet distinctly known what organ secretes this fluid ; according
to some it is the anal glands, which we have considered as kidneys ; and
according to others, on the contrary, the ejected gas is nothing else than
the air accumulated in the colon. This opinion seems to be the most
correct, for in the former we cannot distinctly see how the fluid con-
tained in the bladders could so immediately be transformed into gas«
Another mode of defence, which we have before mentioned, is allied to
this, namely, the ejection of the corrosive juices of the stomach, which
we observe in many of the larvae of the Lepidoptera, in almost all
Carabodea, and in the grasshoppers. It has evidently for object to
deter their enemies, for it is only in moments of danger that insects
eject it, and therewith soil their enemies, as in the Grylli, or project it
against them, as in the rest. The sharp stinking urine of the Dytici,
and the other secretions which we have before mentioned, are cast forth
in the moment of danger to check the enemy.

We have before noticed some peculiar organs of secretion in several
larvae, as, for instance, in that of Pieris Machaon, which are projected
at the approach of danger : they appear, in fact, to be glandular organs
which partly secrete odours and partly liquids, for the purpose of
chasing the enemy. In P. Machaon the furcate organ lies in the neck,,
between the head and prothorax, and the same in Dorilis Apollo. In
the larvae of Harpy a vinula it projects from the tail, in the form of a
filament ; and in the larvae of the Tenthredonodea they lie between the
five anterior pair of ventral feet, and are wart-shaped, transpierced pro-
tuberances, which project only during danger, and then emit a peculiar
odour. In other larvae they lie upon the back, as in the caterpillar of
Lip chrysorrhea. Among the beetles similar organs are found in the
genera Cantharis and Malachius, which in these are seated at the
sides of the thoracic and ventral segments, and are likewise projected

510

PSYCHOLOGICAL PHYSIOLOGY.

in times of danger. It is remarkable that these organs in all the pre-
ceding instances are of a red colour : it might be thence concluded that
the substances which they secrete or contain are very rich in acids.
The larva of Chrysomela Populi has likewise secreting organs upon its
back, in the form of two conical knobs on each segment, whence, at a
time of danger, a white, milky, and strongly scented fluid issues, which
may also serve chiefly as a means of defence. In the processionary
caterpillar, according to a recent discovery of Dr. Nicholai, the whole
external surface of the skin secretes a sharp juice, which is distributed
over the body in a farinaceous form, and which acts very prejudicially
upon all organisms that inspire it ; therefore workmen who are
occupied in woods where this caterpillar is numerous sicken very
rapidly. Bechstein knew that the processionary caterpillar was pre-
judicial to the touch, but he ascribed their effects to the hair that was
removed by it.

Other larvae, which have not received means of defence in such
organs of secretion, nor in the thick hairy coat that envelopes them,
construct cases for themselves, into which they retire upon the approach
of danger. We find such among the larvae of the Coleoptera , namely,
in the larva of Clythra , which all dwell in cases formed by themselves,
and in which they change into pupae. Among the Lepidoptera, the
remarkable genus Psyche forms such cases of morsels of wood, and
there change into the pupa, and even the naked apterous female still
continues to dwell in it. Besides these, the family of the Pkryganea
are furnished with this means of defence ; their larvae live in the
water, and form cases of small stones, pieces of wood, shells, &c.,
which they also close with a distinct lid when they change.

The sting is the chief weapon of offence. The majority of insects
furnished with a sting as a means of defence belong to the order of the
Hymenoptera ; it is but recently that a stinging lepidopterous insect
has been found, and which we have before mentioned. It is always
the female which possesses the sting, or else the neuters ; the males
never have it. We refer to the anatomical division of this work for its
structure, and we can only say of the way in which it is used as a
weapon, that the insect upon the approach of danger projects it from
the abdomen, and thereby endeavours to wound its enemy with it. It
is not so much the mechanical injury that occasions the pain as the
poison which is injected into the wound. There are solitary instances
of two or three stings being present at the same time, and which also

INSTINCT OF NUTRITION.

511

wound in conjunction, namely, among the wasps, and in the genus
Onyderus . I have hitherto neglected to inspect more closely the struc-
ture of this threefold sting, but I surmise that in this case the several
setae of which the simple sting consists are more remote from each
other, and therefore project separately from the abdomen.

The stings of the Diptera are not weapons of defence, but organs
whereby they may imbibe their nutriment. They are therefore only
used for this purpose, and not as a means of defence. Among the
Hemipiera , which likewise possess organs of puncture in the mouth,
the latter may not be affirmed, for the Notonecta defend themselves
with their proboscis, and their puncture, as was before mentioned, is
very painful.

II. Instinct of Nutrition.

§ 290.

The food which insects take is more important to their self preserva-
tion than all these means of defence. We have before classed their
chief kinds, and can here only make a few observations upon the way
in which they procure it.

In the majority of insects this takes place without much art or
exertion, in as far as the insect in its most helpless state, namely, as a
larva, finds itself generally in a place where its food is very abundant.
It has to thank its mother’s care for this, for she lays the eggs mostly
where there is food for the larva, or else 'provides it with food in its
cell, in whichshe has enclosed the egg. But these instances do not
properly belong here, but to the following chapter, where we shall
speak of the means provided for the conservation of the species, and
only such facts, as convince us of the instinct of the insect for its
independent supply of food, shall here be mentioned. Among our
native beetles the larvae of the Cicindelce exhibit these instincts. They
dwell in sandy places, where they dig a cylindrical hole by means of
their feet and mandibles, wherein they sit. They watch from this place
of concealment all insects that pass by, and which heedlessly venture to
the margin of the hole, when they fall in, and are then devoured by
the larva. Miger, who first observed this larva *, has given a detailed
account of its economy. The plan adopted by the larva of the genus

* Annales du Museum d’Hist. Nat. v. 14.

512

PSYCHOLOGICAL PHYSIOLOGY.

Myrmecoleon , in the order of the Neuroptera, is very similar to this,
which is also found abundantly in sandy places, and here excavates
a funnel-shaped cavity, at the bottom of which it lies concealed with
its mandibles projecting, and it likewise seizes and sucks all insects
which by mischance fall in, and then throws away the empty case
by placing it on its head and giving it a jerk. These two larvae are,
however, almost the only ones in which we observe such striking and
exceedingly sagacious methods of procuring their food, the majority of
the rest of the carnivorous larvae hunt about like the beetles for prey.
The larvae of the Carabodea are found especially in the earth, beneath
stones, and in other nooks, where they prey upon the vegetable-
devouring larvae, which seek a place of safety. It does not, how-
ever, appear that the law that carnivorous animals shall not destroy
other carnivora is strictly obeyed, for indeed the larvae of one species
frequently devour those of another, which Miger states of the voracious
larvae of the Cicindelce. The black larva of Calosoma sycopharta
devours with appetite the caterpillar of the Lepidoptera , especially that
of Liparis dispar ; consequently, where this caterpillar is abundant
they are also abundantly found. They are then observed to pursue their
food even by day, and knowing that the caterpillars are found especially
upon trees, they themselves climb up and there attack them. It is
chiefly in the morning about sunrise that they are to be found there ; I
have also detected the perfect insect in the same pursuit. We cannot,
however, maintain that other larvae possess peculiar instincts for obtain-
ing their food. The vegetable feeders are deposited in the egg state
by the mother in the vicinity of plants, where they find their food.
This is likewise the case with the perfect insect. The Lepidoptera
and Hymenoptera fly from flower to flower, visiting at pleasure now
this and now that ; insects which devour vegetable substances dwell
in the vicinity of the plants which serve them as food, or if less particular
in their choice, they feed wherever it presents itself ; a few undertake
wider migrations for theirs, as the locust, and devour every vege-
table they meet with. But it is not a migratory insect in the same
sense as in birds, but it is found almost all over Germany, sometimes
singly and sometimes in bodies, but sometimes their numbers are so
great that one district is no longer able to support them, and they then
undertake their devastating expeditions. Other species of this genus
also seem to possess this wandering propensity, at least the South

THE SEXUAL INSTINCT.

513

African migratory locust is specifically different from the European
one. Whether the migrations of the Libellulce have the same object
cannot be ascertained with certainty, but it is improbable, as they are
carnivorous.

NINTH CHAPTER.

OF THE CONSERVATION OF THE SPECIES.

THE SEXUAL INSTINCT.

§ 291.

The impulses which nature has implanted for the conservation of
the species are more evident than those for the preservation of the
individual. We have before hinted that all the several conditions of
insect life appear to have for their chief object the conservation of the spe-
cies, and we have also ascertained that the life of the individual termi-
nates with its sexual activity, it having thereby fulfilled the object nature
contemplated through its means, and it may then quit the stage. If
now, therefore, we collectively comprise together the several phenomena
which refer to the sexual functions, we shall find them to consist of
two chief divisions, under which the various functions may be classed.
These are, the impulse which brings the sexes together, the copulative
impulse, and that which urges the impregnated female to take such
care of her eggs and young that they may thrive under favourable cir-
cumstances, an impulse which admits of comparison with the maternal
love of the human race, and which in insects also exhibits itself in the
anxiety of the parent for her progeny.

I. Copulative Impulse.

§ 292.

This impulse presents itself in insects so soon as they have attained
their perfect state, and it henceforward predominates throughout the life
of the individual. The duration of the lives of insects depends upon
their copulation, for the majority die speedily after its accomplishment,
and only those which have been prevented from the act can survive

l l

514

PSYCHOLOGICAL PHYSIOLOGY.

longer. Hence copulation is the object for which Nature produces
individuals, and she must necessarily be anxious for its most easy and
securest attainment. We find several arrangements to promote this
object, which facilitate the mutual meeting of the sexes, some of which
are merely corporeal, and others are called forth by the instinct. In
the majority of cases it is in the male that this impulse first becomes
active, and it is therefore they especially which seek the female. When
difficulty attends this, Nature has often provided peculiar organs to
render it more easy. One of the most usual means consists in the
males being more numerous than the females ; indeed it is not possible
to give the exact proportions of the sexes, but it is, according to
De Geer’s calculation, among the Phalence, about three to one; or,
according to Lyonet, about four to one. Among the bees there are
several hundred males and only one fertile female. Another means is
the greater activity of the male. They are generally smaller in size,
have longer wings, longer antennae and legs, or have wings in many
instances when the female is without them, as in Lampyris, Symbius,
Psyche, many Phalence ( Acidalia brumata, &c.), the Mutillce, Methoca ,
Myrmosa , &c. Sometimes, also, the females have peculiar marks of
distinction, as in Lampyris, in the female of which the light emitted
is considerably brighter than that produced by the male. A reversed
relation occurs in the Achetce, Locus tee, and Cicadce, in which the
males are furnished with a vocal organ not found in the females. We
observe the same phenomena also in the singing birds, among whiefi
the males only are the songsters. Thus Nature wished, by furnishing
the males with distinguishing characters, to place them in a condition
to lure the females from their hiding places, which in most of the men-
tioned instances it is their habit to resort to. Others, as the nocturnal
Lepidopiera, have received for this purpose a very developed sense of
smell, by means of which they can discover the female at considerable
distances, to whom they immediately flock. I have myself observed
males of Liparis salicis fluttering around my breeding-cage, in which
there were several just developed females of the same species ; upon
my letting them into the cage they immediately copulated. This
instinctive impulse, the satisfying of which nature has thus faci-
litated, is most conspicuous also in the Lepidopiera . The males of
many Noctuce will even copulate with impaled and half dead females,
and the excitement of other insects occasionally urges them to an inter-
mixture with individuals of a different species, and even of a different

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515

genus. Several such instances have been observed; Rossi*, for
instance, detected a connexion between Cantharis melanura and Elater
niger, the former the male, the latter the female ; Miiller, of Odenbach,
observed a connexion between Chrys mela graminis and Chry. polila,
and of Attelabus coryli and Donacia simplex , in both instances the
first was the female ; and Heyer, of Lüneberg, saw a female Cantharis
rafa actually connected at the same time with two males. Treviranusf
mentions other cases of such commixture, namely, one between a male
Melulontha agricola and a female Cetonia hirta ; and two others,
observed by O. F. Müller, in which Chrysomela Mnea was connected
with Galleruca alni , and Papilio Turtina with Papilio Janira. It is
uncertain whether such mixtures have been productive, but, from the
analogy of the superior animals, we might say no ; should, however,
the copulation of closely allied species actually produce young, these
would not be able to unite productively, as is proved by the
general rule of analogous instances in the superior animals, yet this,
even, is not without exception. Hence Gravenhorst’s opinion, that
from such bastard copulations of allied species many intermediate forms
originate, must be totally rejected, exclusively of the view that in case
of such a course in nature, its beautiful regularity and order would
speedily terminate in illimitable confusion, of which, however, there is
not the least proof.

II. Affection for the young.

§ 293.

The chief business of the male terminates in copulation ; but it is
this which first excites in the female the impulse that stimulates her to
the completion of her most important occupation. This impulse hence-
forth exhibits itself to us in her affection for her progeny, it is the
cause of her activity after copulation, and in aid of which her most
distinguishing and remarkable instincts are developed. We will now
survey these in detail in the several orders.

In the beetles this instinct presents itself almost solely in the
suitable depositing of their eggs. Just as the birds of prey are not
distinguished by any artificial preparation of their nests, so we may
maintain of the predaceous beetles, that they, as those birds place their
nests on elevated inaccessible situations, deposit their eggs in concealed

* Germar’s Magazin, vol. iv. p. 404. ■f Vermischte Schriften, vol. i. p. 22.

L L 2

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PSYCHOLOGICAL PHYSIOLOGY.

and retired places safe from the attacks of their enemies ; it is, therefore,
very rarely that we find not merely their eggs, but even their young larvae.
Nor do we know whether the mother furnishes them with food for their
first supply, yet it is much to be doubted, as many of their larvae, which as
remarkable exceptions do not feed upon animal matter, as, for instance,
the larva of Zubrus gibbus, immediately find in their vicinity a suffi-
ciency of food in the young roots of corn *. Thus, also, the eggs of the
water beetles may be deposited, without any particular care on the
part of the mother, at the bottom of ponds and pools in which the
beetles are, for the young larvae will find in the water a sufficiency of
other larvae to feed upon. The modes of life vary considerably in the
Stapkylini in their perfect state, but the majority live upon animal
substances. But the larvae are rarely found, and least likely to be so
there where we discover the perfect insect; we may therefore conclude
that they also live beneath the earth, where they find their food in con-
cealment. The larvae of the carrion beetles are more visible, they are
frequently observed in the society of their parents, and we may therefore
conclude that the female deposits her egg in the carrion, where the
young immediately find nutriment. In the large family of the Lcnnel-
licornia there exists a great difference both in the nature of the food and
in their mode of depositing their eggs. The vegetable feeders lay their
eggs in the earth, where we find the larvae feeding upon roots, or even
upon the soil; the excrement feeders, on the contrary, likewise dig
holes in the earth, wherein to deposit their eggs, but they supply their
larvae with food, by rolling up balls of excrement, in which they envelope
their eggs. We therefore occasionally find the beetle occupied in care-
fully pushing this ball along, as we have recently related of Gymno-
pleurus pilularius. Copris lunar is, which prefers the dung of sheep,
is said to use the individual lumps of it as balls for her eggs, depositing
a single one in each, and then burying them. Examples exhibiting
greater skill are rare among the Coleoplera, yet Hydrophilus piceus,
according to Miger, forms a little boat of substances which it fixes
together by means of some viscid fluid, and herein depositing the eggs,
closes it, leaving it to its fate. The capricorn beetles, and bark beetles,
which busy themselves with the destruction of dead trees, lay their
eggs in and upon them, generally beneath the bark, and it is their
larvae which gnaw the wood in all directions. The same is the case

* German’s Magazin, vol. i. part i. p. 1, &c.

AFFECTION FOR THE YOUNG.

517

with the Anohia and the Ptini, but these prefer dry manufactured
wood, paper, &c. ; they consequently produce, in their larva state, the
same injury to furniture and libraries. The fur beetles and fur moths
also are destructive only in their larva state, and it is by the care
of the mother that they are deposited in furs and wool, which they use
as food. The Chrysomelce, as larvae, live upon leaves, and are deposited
upon them in their egg state by the mother ; the Curciilios, which
prefer especially the seeds of plants, are deposited in flowers as eggs,
and during the development of the fruit they devour its substance, for
which purpose nature produced them, and then, instead of a shell pro-
ducing a kernel, it produces a beetle.

All the other orders furnish us with similar instances of the affection
of the parent for her progeny. It would lead us too far Avere we thus
to go through them individually to show their consimility by adduc-
ing instances ; we will merely remark, that the large order of the
Lepidoptera , throughout all its members, exhibits the same anxiety
and care in depositing their eggs. Almost all caterpillars feed upon
leaves, and therefore almost all eggs are deposited upon the plants
themselves, or in their proximity. The majority are much exposed,
and are therefore enveloped by peculiar coverings, which the mother,
precisely as among the birds, procures from her own body. Others
have, instead, a hard glue-like case, over which a second woollen cover-
ing is spread. The fruit moths deposit their eggs upon ripening fruit,
unripe fruit they will not touch.

The eggs of the Orthoptera are deposited in general in the earth,
usually in particular holes dug expressly for this purpose by the
female, and which are again closed so soon as she has placed all her
eggs therein. As the young immediately after their development
seek the light, and feed upon leaves of all kinds, provision furnished
by the parent was here also unnecessary ; whereas the Diptera and
Hemiptera lay their eggs generally in such places as the developed
larva can immediately find food. We thus find the eggs of the
Syrphodea among the plant lice, which the larva devours, or in the
nests of the bees and wasps, whose honey they help to devour. The
eggs of the true flies ( Muscce ) are laid by the mother in dung or
carrion, which substances constitute the food of the larvae. The
gnats let their eggs fall into the water ; here the larvae are deve-
loped, and one species of them devours the other with as much voracity
as they themselves are again seized by the larger larvae of the water

518

PSYCHOLOGICAL PHYSIOLOGY.

beetles. The eggs of the bugs we find upon the leaves and stems of
plants, the juices of which the larvae imbibe; the same in the plant
lice and Cicada , which select the same materials as food. The water
bugs live as larvae also in the water, and feed upon prey. We there
find their eggs, but generally placed in rows affixed to the stems and
leaves of plants growing beneath the water.

§ 294.

But the maternal care is exhibited most strikingly in the order of
the Hymenoptera, and here presents itself in such a variety of forms
that we cannot refuse ourselves a detailed description of this attractive
subject.

The Tenthredonodea, whose larvae, like the caterpillars of the Lepi-
doptera, feed upon fresh vegetable substances, cut with their saw- shaped
ovipositor the surfaces of leaves, and in these incisions deposit their
eggs. Here the larvae develope themselves,' and subsequently feed
upon the same leaves. Thus their care for their progeny perfectly
corresponds with that of the majority of other insects. The Ichneu-
mons also are not distinguished by a greater anxiety from the rest ; they
deposit their eggs in other larvae, particularly in the caterpillars of the
Lepidoptera , and for this purpose they bore a hole with their pointed
ovipositor in the skin of the caterpillar, through which the egg passes
into its body. In the gall-flies the egg is also deposited in the paren-
chyma of the leaf, but steeped in a corrosive moisture, which occasions
a powerful influx of the juices to the wounded part. This thereby grows
gradually into a cellular body, the so called gall-nut, in the inside
of which the larva lives, feeding upon the juices ; it changes here into
the pupa, and also into the perfect insect, in which state it pierces
through the dwelling nature prepared for it through the care of the
mother, and then first sees the light of day. But this care is still more
striking in the fossorial wasps, all of which dig subterranean cavities,
whither they convey insects which they have caught and killed, and
in which they deposit an egg ; the body serves the young larva as
food, and the hole is a secure dwelling. We have before admired the
strength and patience which many species of this family apply to the
attainment of their object, and we then cited the large Ammophila
sabulosa as the best known and most striking instance. During the
summer we continually observe her incessantly employed in this labour ;
we may also admire her sagacity in the selection of a suitable soil.

AFFECTION FOR THE YOUNG.

519

neither too loose nor too firm, and feel astonished at the apparent
toil to which she must so repeatedly subject herself. But all the
allied genera are subjected to the same. Pompilus and Pepsis proceed
in the same way. Pelopceus constructs sinuous passages in old timber ;
Trypoxylon and Crabro seek such holes in walls and palings, and into
which they convey the larvae they have seized, and where also they lay
their eggs. Cerceris and Philanthus likewise dig holes in the ground,
but they select a loose soil, whence they are found most frequently in
sandy situations. Philanthus apivorus is notorious as a dangerous
enemy to bees, as it only makes use of the honey bee as food for its
larva, and which it seizes wherever it finds them *.

Many wasps and bees have similar habits. The majority, however,
excavate themselves the holes in which they deposit their eggs,
and which they line with peculiar substances, either made by them-
selves or obtained elsewhere. But they are nevertheless distinguished
from the former by their not in general supplying their larvae with
other insects or their larvae f, but either with the pollen or the nectar of
flowers, either in its raw state or previously prepared by them. Among
the wasps this custom is found in the genera Odynerus, Eumenes ,
Pterocheilus, &c. They construct separate dwellings for their larvae
in clay walls or clay banks, and sometimes even form a tubular entrance
to it, still further to prevent the intrusion of unwelcome guests. The
egg is then deposited in the cavity, and provided with a lump of pollen
intermixed with honey. Among the bees, the whole group of Andrence
form such nests, yet not in walls, but perpendicularly in the firm earth.
The depth of these shafts, which generally descend in a direct line, is
not trifling, it frequently exceeding a foot ; at the end of the shaft lies
the egg, or larva, embedded, as it were, in a quantity of pollen and
honey. Many true bees construct them similarly, but the dwellings
of their larvae are generally more artificially formed. Thus the Mega-
chiles eiivelope both egg and pollen in the leaves of plants, which they
cut off in pieces, and have gradually wrought together ; the Anthidia
furnish their entire cells with the woolly clothing of many plants, for
instance, of the several species of Stachys . They thus form in the

* See a paper of mine upon this subject in the first part of the Trans, of the Entom.
Society of Loudon. — Tr.

■f* According to Miiller’s observations (Germar’s Mag. vol. iii. p. 61.), the hornet
supplies its young with the bodies of bees, both neuters and drones, as well as with the
honey of flowers.

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PSYCHOLOGICAL PHYSIOLOGY.

structure of their dwellings a tolerable transition to the elaborate
dwellings of the social bees and wasps.

§ 295.

This indication shows that the nests of the wasps and bees which
live in society are nothing more than dwelling-places for their progeny.
This is their first and chief purpose, and all others which they at the
same time execute proceed necessarily from this. If we examine this
more closely, we shall find that among the wasps and the humble bees it
is always the female which lays the foundation of such a dwelling.
The impregnated wasp seeks a place where she can deposit her eggs,
when she finds it she constructs a cell, and deposits an egg in it. Instead
now of seeking another spot, like the solitary wasps, she remains
where she commenced, and adds another cell to the first ; thus the first
layer is formed. In the interim the first eggs have become larvae ; these
larvae are now carefully fed by the mother until the time of their change
into pupae, when each closes its cell, becomes a pupa, and speedily appears
as a perfect insect, which immediately participates in the labour, both
in the structure of the nest and in feeding of the larvae, and upon the
increase of the number of those to be fed, by reason of the increasing
fertility of the first female, the number of the nurses and labourers also
increases, until at last from small beginnings a numerous society is
formed. That the first born young wasps may immediately participate
in feeding the younger larvae, they are, as it were, placed in a maternal
situation, and it is therefore that they are made barren by being prema-
turely ripe, and the one female function, that of conception and produc-
tion, they sacrifice for the other, the feeding and nursing of the young,
and it is hence that they are abortive females. Experience has proved
that this abortion is produced by the defective feeding of a truly female
larva.

If, now, we more closely inspect the several social communities of
insects, the object of all of which is the nourishment of the young,
the most imperfect of all presents itself in the society of ants. It
consists of winged males and females, and apterous abortive females,
called neuters, or workers, which are besides distinguished from the
rest, especially from the females, by their smaller size. The dwell-
ings in which we find these three members of a society of ants are
found in the earth, and consist of passages which lead to larger vacant
spaces, all of which again stand in connexion, and which generally have

AFFECTION FOR THE YOUNG.

521

several outlets. The hollow spaces lie in several stories over each other,
and are used only as rooms for the larvae ; the ants do not make a provi-
sion of food, but hybernate within their dwellings, from which they arouse
upon the approach of spring. Their food consists of sweet animal and
vegetable juices, which they convey also to the larvae; they are particu-
larly fond of the juice that exudes from the tubes upon the abdomen of
the plant lice ; they therefore not merely pursue these creatures, but also
retain them in their dwelling. Their pairing time is August ; immense
multitudes of both sexes then quit their dwelling, and copulate in
flight, especially towards evening, about which time they frequently fly
up and down in the air in myriads. The males die quickly after copu-
lation, whereas the females are either brought back by the neuters to
their former dwelling, or else, either singly or in society, they found
new dwellings, which they speedily populate with their own progeny.
It is remarkable, that before the commencement of their new labours
they purposely deprive themselves of their wings. The young, which
pass but a short time in the larva state, during which they are fed by
the mother, do not quit the egg before the following spring ; and if
neuters, they immediately after their development participate in the
labours of the mother, they feed the larvce, increase the dwelling, leav-
ing nothing for the old parent of the nest to do : whereas in the old
colonies, to which impregnated females return, or therein pair with the
males, the eggs are not laid until the spring, until which time no young
progeny is to be found in the nest. Thus the entire society of neuters,
with the few impregnated females among them, and without any young
ones, hybernate. As soon, however, as the first warm sunshine of the
spring rouses them they re-commence their labours, they mend their
dwelling, seek food, and convey nutriment also to the female. These
then lay eggs, from which the larvee soon creep, the whole development
of which, from the egg to the imago, is so rapid that it is completed in
twenty-three days. The males and females now present themselves,
but they remain in the dwelling until the middle of the summer, and
then quit it for the purpose of pairing. When this is fulfilled the
whole series is repeated in the nests founded by the young impregnated
females. In the progress of the several occupations exercised by ^he
different members, and especially by the neuters, the ants develope
striking art and proofs of the great perfection of their instinct. They
always select sunny but not too dry places to lay the foundations of
their nests, but they always avoid moist situations, and give consider-

522

PSYCHOLOGICAL PHYSIOLOGY.

able preference to the foot of a hollow tree, or its interior when it has
but small accesses. They here labour with considerable industry in
laying the foundations of the nest, each assisting the other, and in
the course of a few days we perceive a structure rise having several
outlets. If the nest be upon the ground there are generally affiliated
colonies in its vicinity, which are in a constant animated intercourse
with the parent state. This intercourse is facilitated by the construc-
tion of particular roads, which in a loose soil are tolerably deeply fur-
rowed, and upon these roads we observe innumerable neuters inces-
santly coursing to and fro. All the obstructions that may here interrupt
them are removed, each lends its assistance, and if there be at first too
few for the purpose, by means of signs they urge other comrades to
participate in the labour. Along these roads they convey into the
dwelling the food for the larvae, which consists in captured insects,
caterpillars, small earth worms, and other, mostly animal, substances.
We have before related that the ants possess the faculty of communi-
cating their views to their comrades ; all that requires the labour of
many immediately occupies several, and to this participation they urge
each other. Huber *, to whom we are indebted for the most interest-
ing observations upon the economy of the ants, has observed them go
out in troops to enjoy some dainty repast when such has been com-
municated by a compatriot, whither also more and more proceed, until
at last nearly the entire population of the nest is found there.
Once, upon separating a portion of the community, which he kept in a
closed place for several months and then brought them back to the
garden where the nest was, he observed their former fellow-citizens
gradually emancipate them, after their dwelling had been discovered
by some stray ones. But still more remarkable than all this is the
warlike and predatory excursions which Formica rufescens and F.
sanguinea undertake upon losing their young progeny of neuters. They
then proceed in hosts to the nests of other ants, master its entrances,
and convey away their young. These then grow up as helots in the
foreign community, execute all the labour necessary for the advance
and preservation of the state ; they seek food, increase the building,
sun the larvae and pupae, convey them back into the nest, and assemble
with their subduers without recalling their disgrace. Thus originate
the variously coloured and intermixed communities.

* P. Huber, Recherchcs sur les Mceurs des Fourmis Indigenes. Paris et Geneve,
1810. 8 vo.

AFFECTION FOR THE YOUNG.

523

§ 296.

The economy of the remaining social Hymenoptera differs from that
of the ants by their constructing an artificial nest for the reception of the
society, and not merely excavating cavities in the earth for this purpose.
The wasps, which most closely agree with the ants in their societies,
build some their nests in holes in the ground, and others pendant
from the boughs of trees. The material they use is wood, either fresh
or rotten, which they grind to a fine powder by means of their powerful
mandibles, and then moisten it with a viscid liquid, which is probably
the secretion of the salivary glands, when they prepare it into thin
pasteboard surfaces. The size of the nest varies considerably ; in
Polisles gallica it consists of about twenty roundish cells, open beneath,
which form a small convex comb, and which is attached to some object
at its highest point ; Vespa holsatica affixes a second larger, and some-
times a third smaller comb to the first, which are connected together
by many perpendicular, tolerably thick pillars, and the whole nest is
enclosed by two or three ovate cases, the lowest of which alone enve-
lopes all three combs, each of the succeeding ones being about one-third
shorter. The entrance to the interior is in the pendant apex of the
first envelope. In the nest of Vespa vulgaris , which is placed in a
large hole in the ground, the external case consists of a thick, tolerably
strong pasteboard, formed of several layers, and the combs are more
numerous, the central ones larger, and the entire nest attains about the
size of a moderate melon. Others, for instance, the exotic species
( Vespa tatua, Lat.), build a very large but similarly pendant nest,
the entrance to which is also beneath, and the superior surface is covered
with a multitude of conical knobs. Vespa crabro (the hornet) prefers
the cavities of trees for her nest : it differs from that of the common
wasp both in size, which is that of a moderate gourd, and also that the
external envelopes are separated from each other by the space of at
least half an inch, whence passages lead from the exterior to the
interior ; it therefore appears upon the first glimpse to be covered with
large scales. The much smaller nest of Vespa Germanica is very
similar, but it is placed in the earth, at about six inches from the sur-
face ; the form of the cells is originally, as also in the humble bees and
bees, that of a cylinder, which subsequently, by the pressure of the
rest, take that of a hexagon. This last regular form of the cells has
ever been considered one of the most extraordinary things, and its

524

PSYCHOLOGICAL PHYSIOLOGY.

precise repetition in all the societies of the Hymenoplera as a proof of
the great skill of these insects ; but nothing is more natural and neces-
sary in the whole economy of the bees and wasps than this form of
their cells ; if, for instance, large soft tubes are to be so placed side by
side that they may occupy the least space, the form conditionated by
the point of contact, and the equal pressure upon all sides must neces-
sarily be that of an hexagonal prism, as may be proved by mathematical
demonstration. The bees and wasps consequently, from the innumer-
able multitudes inhabiting a nest, or hive, must necessarily apply the
smallest space possible to their structure, that they may be enabled
to introduce a greater number of cells, and hence they become hex-
agonal : nature also only aims at what is necessary, and not at what is
superfluous, and there would have been a waste had she allowed the
bees to construct their cells independent of each other, for much unap-
propriated space would have remained. Besides, each cell is by no
means so determinate an hexagonal prism, but rather a cylinder pressed
flat by its contact with six other cells ; no sharp angles are found inside,
and the sides where the angles of three cells meet are thicker than where
two cells lie contiguously wdth their flat surfaces. Among the humble
bees, in consequence of the smaller number of the inhabitants of their
nests, so strict an economy of space was not requisite, the cells but
loosely touch each other, retaining their original round form flattened
only at their extremities.

The inhabitants of a wasp’s nest likewise consist of three distinct
groups, namely, of males, females, and neuters, which last are also
abortive females. The foundation of the community is laid by the
female, and indeed very early in the spring. The impregnated female
hybernates during winter in suitable places, without laying her eggs, and
she first seeks, on the approach of spring, after being aroused from her
winter torpidity, a place adapted to the structure of her nest, which she
begins as soon as she has found such a situation. When the first cells,
or the first and smallest comb is completed, she lays in each an egg,
whence in the course of a few days a young larva creeps. These she
feeds with the juices of other insects, especially of Hymenoplera, until
they change into pupae, when the larva closes the lower aperture with
a web of silk. In the course of eight or ten days the young wasp
presents itself, which, like all the following ones, is a neuter, and con-
sequently a worker, which immediately proceeds with feeding the larvae
and increasing the nest. When all the neuter wasps are thus developed.

AFFECTION FOR THE YOUNG.

525

the development of the male and female eggs which the old mother
has laid in the interim is proceeding, while the neuters continue to
increase the nest. The perfect males and females remain for some
time in the nest, and it is only towards the end of the summer that they
quit it. They now pair, after which the males die, but the females
prepare for their hybernation. After the males and females have
quitted the nest the community appears to have lost its importance,
the neuters disperse, and soon die for want of food ; the nest itself
then loses also its consequence, its community is dispersed never to
return again, and it falls to pieces like a deserted ruin. The skill and
instincts which the wasps develope during their lives refer therefore
almost exclusively to the preparation of their indeed very artificial
nest ; combined undertakings like those we observed among the ants,
we do not detect in them, yet they nevertheless appear to possess a
power of communication, for many of the neuters assemble if an enemy
appear before their entrances, and endeavour to beat him to retreat
by their desperate attacks. These troops are said to be assembled for
battle by the guards placed to watch the entrance.

§ 297.

Among the social bees, the society of humble bees is the least perfect.
It also consists of males, females, and neuters ; and it owes, like that
of the wasps, its first foundation to a female. For this purpose the
impregnated female, which has lain torpid throughout the winter,
seeks in the spring a place suitable to lay the foundation of her nest.
She in general seeks shady places concealed among bushes and tufts
of grass, where, with much labour, she digs a cup-shaped but yet very
slight cavity, over which she spreads an arch, formed of light dry
moss. The internal surface of this arch she clothes with a thin layer
of wax, and attaches to it the first comb, consisting of large, oval,
■waxen cells, very loosely connected together. The entrance to the nest
is beneath where the arch joins the margin of the hole, but in general
a long vaulted passage leads from the exterior to it, that the entrance of
enemies may be rendered more difficult. When the first cells are
completed the female lays eggs in them, and then fills them with pollen
and some honey, for the nourishment of the young. If this does not
suffice she also feeds them. These larvae merely produce workers,
which immediately after their birth assist to feed the younger mem-
bers, for which purpose they especially collect pollen and honey. The

526

PSYCHOLOGICAL PHYSIOLOGY.

development of the neuter larvae then proceeds, until all are perfected ;
when the old female lays male and female eggs in the new or cleansed
cells. The neuters are chiefly occupied with feeding the larvae
thence disclosed ; they are continually collecting honey, which they
convey to the larvae : this honey is also their sole nutriment, for they
do not receive pollen, like the larvae of the neuters. More honey is
conveyed into the empty cells. These consist, singularly enough, not
of wax, but of the web spun by the larvae, which has previously trans-
formed into the pupa state within the cell. When this web is com-
pleted the workers convey away the wax encompassing it to form new
cells, and subsequently use the web as a jar for the honey. Towards
the end of the summer the young of both sexes quit the nest, and pair
at large ; the males die, but the females return to the nest, where they
hybernate in cells prepared by themselves, and filled with moss, and
some occupy the succeeding spring the old nest, whilst the remainder
go forth to form new ones. The neuters and the hybernating females
live in the interim upon the collected honey.

Many writers speak of smaller females among the humble bees, as
well as among the wasps, which only lay male eggs, and which appear
either with the neuters or immediately after them. These are evi-
dently neuters which have not wholly sacrificed their sexuality, and
which are consequently capable of procreation. I doubt whether their
existence be absolutely necessary, and also, notwithstanding the uni-
form assurance, that they lay only male eggs. Perhaps the female
maggots, either as being superfluous or less perfect, by proceeding from
a weaker mother, are killed, and only the males reared. — Among the
bees we also occasionally observe fertile workers, or smaller females.

§ 298.

The society of the bees is doubtlessly the most perfect of all, and it
differs also in many respects from those already described. It likewise
consists of the same members, namely, of males or drones, and females or
the queen, and the neuters or workers ; we find a multitude of the first
and of the last, but of females only one old one, and, according to the
differences of season, two or three young ones.

The first founding and structure of the nest of a community of bees,
which is called the hive, originates indeed with the female, but is
executed by the neuters. If, for instance, an old hive be provided in
the spring with a multitude of youthful progeny, so numerous that the

AFFECTION FOR THE YOUNG.

527

old abode can no longer retain them, a great portion of the neuters, led
by a single female, migrates or swarms, and proceeds to form a new
colony. This swarming is repeated several times even in one hive,
which may thus give rise to as many as four other colonies. The first
swarm quits it about the middle of May, and the following ones from
week to week, until the middle of June. The first that migrate consist
chiefly of the older inhabitants of the hive, and their queen is also the
old one who had hybernated with them ; the subsequent swarms are
led by young impregnated females. The swarm quitting the parent
hive has at first no dwelling place, but the queen, after a short flight,
settles at some spot, and all the workers accompanying her do the same
around her j single neuters now fly forth to seek a place which the
swarm can inhabit. They in general select for that purpose hollow
trees, or other dry situations that they may meet with ; when such a
cavity is found the entire swarm, with the queen, immediately occupy
it. So soon as the swarm has taken formal possession of the dwelling
the neuters commence their labours: they first investigate all the
entrances, and close all excepting one, which forms the true entrance,
which is in general of but small compass, but which is decreased to the
requisite size if it be too large. The material with which they close the
entrances, and also cover the interior surface of the cavity, is called
propolis, metys, pissoceros ; it is a resinous substance, which they
collect from the clammy and resinous buds of the birch, the sallow,
poplars, chestnuts, &c : it differs from wax by its peculiar balsamic
smell, by its combustibleness, and its resinous components. They do
not appear to prepare it, but apply it to their purpose just as they find
it. Their second building material, but of which the cells alone are
made, is wax, which is a peculiar secretion of the bees ; of the organs
which prepare it we have before spoken. The tablets secreted between
the ventral segments are removed as soon as a bee wishes to build, then
crumbled and dissolved by means of the alkaline saliva into a pap,
when it is applied to the construction of the cells. These cells they
do not construct like the wasps and humble bees, in horizontal combs,
but in perpendicular ones, which run from the summit of their dwelling
to its base ; both sides also of these combs are occupied by cells, and not,
as in the former insects, the lower side only. The cells are of a roundish,
slightly hexagonal form, and terminate at their base in triangular points
bordered by indistinct rhomboidal surfaces, each of which borders a
third of the opposite cell : thus each cell rests upon three of the oppo-

528

PSYCHOLOGICAL PHYSIOLOGY.

site ones, and their centre meets exactly where the edges of the three
cells join. This phenomenon, however skilful it appears to be, has but the
object of saving all space, which could be attained by this and no other
means, and which admits of being mathematically demonstrated. We
here find another proof of the wisest adaptation to the purpose so con-
stantly observed in nature ; but the choice of means for attaining it must
not be ascribed to the free intellectual power of the creature that employs
it ; it is but the expression of the eternal necessity and uniformity to
which the instinct of the creature is subjected. The number of combs
in a hive depends upon the space ; the central one is first constructed,
and brought down to the ground, on each of which others then follow at
the distance of about half an inch from the first ; thus by degrees the
whole hive is filled with combs. The size of the cells also varies, the
smaller ones serve for the reception of the neuters and the provisions,
the larger ones contain the male maggots ; for the royal maggots, of
which there are from three to four in each hive, distinct cells are
formed upon the margin of the comb, but which, however, never touch
the walls of the nest. They are in the form of a very large, spacious, ovate
cell, which is not horizontal, like the others, but perpendicular, opening
beneath. The aperture is smaller than the body of the cell, and in-
creases with the larva, for the neuters increase both the cell and the
aperture upon the growth of the larva.

Being thus acquainted with the structure of a young bee-hive, we
shall now pass to the examination of its inhabitants and their several
occupations. After the workers of a young colony have built a
requisite number of cells, others then busy themselves with filling them
with honey ; thus a portion of them are constantly occupied with enlarg-
ing the dwelling the while another portion are busied in collecting
provisions. This gathering continues the whole remainder of the
spring and summer, and is carried on even late in the autumn, and
they do not cease until the flowers cease blossoming. The substance
they collect is honey, a thick yellowish fluid, consisting of crystal-
lising sugar, liquid sugar, and a peculiar viscid substance insoluble in
alcohol, which the neuters imbibe by means of their long tubular
tongue from the nectaries of plants, and conserve in their sucking
stomach, which thus supplies the place of a crop ; hence it is thrown
up when the bees wish to get rid of it, when probably it does not
repass through the tube of the proboscis, but through the aperture of
the mouth, beneath the valve of the oesophagus, or second tongue.

AFFECTION FOR THE YOUNG.

529

During this time the true stomach receives no honey for digestion, but
we invariably find in it a crumbly mass called bee bread, consisting
of pollen, which constitutes the true food of the bees, and which alone
is given to the larvae as food. This mass of pollen does not appear to
be received through the canal of the proboscis, but through the true
aperture of the oesophagus. As soon as the colder season interrupts the
collecting of honey the bees gradually become more inactive, when a few
alone loiter about the entrance of the hive, whereas the majority are
preparing for their hybernation within. They then so constrict the
opening that one bee only can pass through at a time, they cling
together in the hive, and appear to have lost much of their former
vivacity ; but they do not become absolutely torpid, but feed tem-
perately upon the honey collected in the summer.

During this whole time the queen reposes quietly in the nest, enjoy-
ing the respect shown to her by the neuters. As soon as some of the
small cells are completed for the workers she commences laying her
eggs, impregnated by the preceding year’s pairing, notwithstanding
having previously laid many in the old hive ; or if she be a young queen
she will have been impregnated by the drones of the old hive prior to
her quitting. In the course of three days after laying the egg the
young larva is disclosed, which is full grown in five days more ; the
larvee then close the cells themselves, in three days more they become
pupae, and in the course of seven days and a half the perfect bee
comes forth, thus its development is completed in the twentieth day
after the laying of the egg. A great number of workers being thus
born, the queen begins to lay male eggs in the larger cells, and from
three to four female ones in the royal cell. When the old queen has
laid all her eggs she dies, and the hive is without a head until the
young royal larvae are developed. This the bees bear very quietly,
whereas the loss of the queen without the survivance of a royal progeny
produces the total dissolution of the society. But if the young royal mag-
gots are developed whilst the old queen still lives she kills them, which the
neuters freely allow ; it will therefore sometimes happen that a swarm,
after the female has laid all her eggs, is without a royal successor.
This evil it is said the neuters remove by transferring a one-day old
maggot from the cells of the neuters to the royal cell, where they rear
it with superior food, whence a queen is developed. The correctness
of this assertion, which is however supported by many direct observa-
tions, has been doubted, and Treviranus has endeavoured to deny it,

M M

530

PSYCHOLOGICAL PHYSIOLOGY.

but it has so much analogy in its favour, and is related by such credible
observers, that it may really be considered as a fact. Thus, therefore,
the hive receives a new queen when the old one dies. This new
queen quits the dwelling, in company with the drones, in the middle
of summer, pairs with some of them, and then returns impregnated to
the hive ; she is here then treated with greater respect than before, she
is stroked with the antennae, licked with the tongue, and they on all
sides offer her honey. Forty-six hours after pairing she lays her first
egg, and then continues uninterruptedly until the 1st of November,
from whence until April she ceases, but which she again resumes in
April, upon the return of fine weather, when the workers again collect.
Now, after having laid none but the eggs of neuters, she lays about
2,000 male eggs, whence, at their appointed time, the drones proceed.
From this time until their pairing with the female they live undis-
turbedly in the hive ; they fly out for food and again return, but they
do not form cells or collect honey, and do nothing else than go out to
feed for their own support. At the time of pairing, which takes place
in June, a great multitude of them fly out with the queen, and return
again after she has paired with one of them, for which it sacrifices its
life ; for, according to Huber and Audouin, the penis torn off remains
for some time in the vagina of the female, fixed in the neck of the
spermatheca. The remaining drones quietly rest until August, even
after the remaining young queens which lead out the subsequent
swarms have been impregnated by them, but at this period the general
slaughter of the drones commences, in which, in the course of three
days, all the males are destroyed by the neuters, and even whilst still
living are cast from the hives. Thus, without males, and provided
with one female, who is however impregnated, and without any pro-
geny for males and females, the inhabitants of the hive hybernate
as well as the young maggots of the workers, all subsisting upon
the collected provisions. It is then also the time to destroy the hive,
to remove the bees, and to take their honey.

The instincts developed by the bees during their life are extremely
remarkable and surprising. Their attachment to the queen, their
endless anxiety for her welfare, the affection and self sacrifice with
which they rear the young, have ever excited the greatest admiration,
and also well merit it. No individual bee cares for herself, her whole
anxiety is for the entire community, and so long as she perceives that
her labours do not miss their aim — the preservation and prosperity of

AFFECTION FOR THE YOUNG.

531

the hive, she is contented with her fate. But as soon as by the
death of the queen this prospect is obstructed, by there being no possi-
bility of obtaining a new queen, she becomes depressed, without
courage, ceases her work, and is lost in the conviction of having lost
her labours. We cannot here relate in detail the several phases
and very special facts which exhibit the comprehensiveness of her
instinct, and they are the less necessary as other works fully show
them ; we therefore refer to the Introduction of Kirby and Spence, as
well as to the admirable work of Huber *. As willingly as we could wish
to refer the actions of the neuter bees to reflective powers, we yet feel
ourselves obliged to deny them this reasoning ; they act rather from
eternal invariable laws, for they have added nothing to it in so many
thousand generations, nor have they lost anything, which therefore
announces their want of freedom, as well as the other side the endless
wisdom of nature is clearly exhibited in the consistency and suitable-
ness of all their proceedings. They are but the wheels and instru-
ments in a higher hand, imperceptible to us, and still more so to them,
which holds the universe ; and to which science must always refer, but
which is depicted to the fancy in a beautiful and attractive image. What
Johan von Müller f has expressed to be the result of his researches
into the history of the human race we may apply to the life of bees, to
the actions of the rest of the world of insects, and indeed to the great
effects of organic nature in general. The whole is an infinite machine,
to whose eternal motion every individual, be it plant, animal, or man,
must contribute, and he who of all that can obey this law is wantonly
deaf — he is judged.

§ 299.

There are two orders, namely, the Neuroplera and Dictyoloptera, to
whose care for their young we have as yet paid no attention, and to
which we now therefore proceed. Among the first, the young larvae
of the Semblodea and Phryganea live in water, and without any
especial care on the part of the mother, are confided to this element.
We are still ignorant of where the eggs and larvae of the Panorpce are
to be found, for their larvae are as yet unknown. The larvae of

* F. Huber, Nouvelles Observations sur les Abeilles ; addressees ä M. C. Bonnet.
Geneve, 1792. 8vo. Nouvelles Observ. sur les Ab. Paris et Geneve, 1814. 8vo.
2 vols.

-f* Vier und Zwanzig Bücher Allgemeiner Geschichte, vol. iii. p. 532.

mm2

532

PSYCHOLOGICAL PHYSIOLOGY.

Raphidia live in the stems of pines, and here hunt up their food, which
consists in other insects ; we might doubtless find their eggs there also,
and presume that they are deposited by the mother at suitable places
upon the stem. The larvae of Myrmecoleon and Ascalaphus live in
the sand, the first, as we have before mentioned, in pitfalls made by
itself, where it watches for prey ; the mother doubtlessly therefore
conveys her eggs there, and deposits them in suitable places, sheltered
from the weather and from enemies.

The same is doubtlessly the case among the Dictyoloptera. The
parasites, or Mallophagi , deposit their eggs at the base of the feathers
or hair of those animals upon which they dwell, and upon which their
young are to reside. It is not yet known where the eggs of the Thysa-
nura are placed. The eggs of the Ephemeres and Libellulce are de-
posited in the water, where the young also dwell, and they are laid singly,
the mother the whilst fluttering over the water. To conclude, the last
families of Psoci and Termites differ considerably from each other in
their modes of life. The majority of the species of the genus Psocus
live in the old stems of trees, and here appear to hunt for prey : Ps.
pulsaiorius is a voracious enemy to collections of insects, and it will de-
vour dry animal substances, namely, the smaller soft- winged Diptera ;
it doubtlessly, therefore, deposits its eggs in the vicinity of such things,
and there leaves them to their fate. This the Termites do not do, but
they build dwellings similarly to the Hymenoptera, where they lead a
still more artificially regulated social life. We indeed possess several
treatises upon the remarkable economy of these insects, distributed
between the tropics (two species are found in the South of France),
and especially an early one by Smeathman *, but still their complete
economy is not fully illustrated, in as far as these tracts contain so much
that is striking and divergent that it cannot well be compared with
the social life of other insects. Their community is said to consist of five
different members, namely, winged males and females, apterous neuters,
or soldiers, which have large heads furnished with strongly projecting
mandibles, unwinged pupae, having a smaller head and the rudiments
of wings only, and lastly, of similarly formed larvae, or workers, differ-
ing from the latter only in wanting the rudiments of wings. The last
of these construct the dwelling, in which they are assisted by the

* Phil. Trans, vol. lxxi. 1781, completed from more recent observations in Kirby and
Spence, vol. ii.

AFFECTION FOR THE YOUNG.

533

pupae ; the neuters are the guards at the entrances, and defend the
nest against enemies ; the males and females are inactive, and remain
until they pair in the nest, they then fly forth, pair, and a single couple
of them are conveyed back again into the nest by the workers, and here
kept prisoners ; the rest die or are destroyed, losing immediately their
wings, when they are quite helpless.

If we receive this description as true, particularly as the Termites,
according to general assertion, belong to the tribes with an imperfect
metamorphosis, and therefore might be active and industrious in their
larva state, yet the circumstance of its being without any analogy in the
whole animal world may be urged against it ; we have no other instance
of the young still undeveloped labouring for the old, and which as larvae
and pupae they must necessarily be. Besides, the assertion that the
neuters are apterous is not correct, for I have had the opportunity of
dissecting winged Termites , through the kindness of the Privy Coun-
cillor Klug, the Conservator of the Royal Berlin collection, and I did
not find the least trace of either external or internal genitalia : nor had
they the large head with projecting mandibles, but one perfectly cor-
responding with that of the males and females. But these Termites
readily lost their wings upon the least touch, and retained but a small
triangular basal piece at the thorax. There is, namely, at the base of
the wing, close to its root, an apparent joint, in front of which the wing
is horny, but behind it soft and membranous, and provided only upon
its anterior margin with ribs. The wing is easily broken off at this
joint, and therefore the neuters very speedily lose their wings, but they
are not, as maintained by writers, wingless. Nor do I see why the
neuters should be merely the defenders, as these among all other social
insects are the true workers. If it may be allowed to start hypotheses
upon subjects that can only be satisfactorily explained by experience,
we might also, with reference to the society of the Termites, admit
of the community consisting of merely males, females, and abortive
females, or neuters, and that the latter were likewise winged, but from
external causes speedily lost their wings after their development. To
these might be added the larvae and pupae which would intermix with
the swarms of neuters, but not participate in the labours ; they have
no wings, and consequently resemble the neuters when the latter have
lost them, thence has sprung the assertion that the larvae are workers.
The larvae and the pupae, in consequence of their much greater voracity,
may especially contribute to the destruction of furniture, as well as of

534

PSYCHOLOGICAL PHYSIOLOGY.

alJ other dead vegetable substances, and are therefore, as well as from
their being necessarily the most numerous portion of the community,
the most dangerous members of the society. For instance, the Termites
have a habit of gnawing all dead vegetable and animal substances
which they can reach, and so vexatiously to mankind that they merely
destroy its interior, leaving the external form unchanged. They thus
bore the balustrades of houses, excavate the planks of the floors, tables,
chairs, and all kinds of household furniture, and they frequently leave
so very slight a case remaining that the whole falls to pieces upon the
least touch. Man has therefore much difficulty in defending himself
from these concealed enemies, and finds his only means of escape in
leaving those parts inhabited by Termites unoccupied. The Termites
gnaw these objects chiefly to obtain thence the materials for their build-
ings, or even also for food. The building that they construct is often
of the shape of a sugar-loaf, and about twelve feet high, which gradually
grows from several small towers of the same description. When, for in-
stance, they have raised a small cone of about one or two feet high, they
lay around the foundations of several similar cones, which are contiguous
at their base ; these are then connected together by a thick wall, which
is continued by degrees in an oblique direction, until a cone of the
given size is thence constructed. Whilst they are still building, the
original small community inhabits the interior of the central cone;
this has in its middle an arched cell about an inch thick, which
is on the same plane with the ground, and in which the old male
and female live. In the circumference of this cell there are many
smaller ones for the soldiers, and around these again others for the
eggs and provisions, which consist of collected drops of gum, pieces of
wood, and other substances which they have found upon their desolat-
ing forays. When the large arch is completed they remove the apex
of the first cone, the entire surface of the described cells is flattened,
and here, as well as upon the walls of the arch, new cells are con-
structed for the provisions. Passages which run along the wall of the
arch lead to their upper cells, and bridges are sometimes constructed,
which spring from the surface above the royal cell, and extend to the
internal wall of the arch. The materials of which they form this
structure is clay and earth, which they artificially combine together, it
then speedily dries in the sun and becomes a hard, firm covering, that
in time is covered with grass, and will easily bear the weight of a man ;
the internal cells, especially those for the eggs and provisions, are

AFFECTION FOR THE YOUNG.

535

doubtlessly constructed of splinters of wood fastened together with
gum. All these cells are connected by means of small apertures, and
several apertures also open from the surrounding spaces into the
central royal cell ; the exterior outlets are not perceptible, they lie
at the foundations of the house, and consist in passages, which also
pass beneath the earth, and only at distant points open to the surface.
At these the Termites , which pass in and out, present themselves.

The following is the economy of the state : — At the termination
of the hot season, when the moderated temperature of the rainy period
announces itself by cooler winds, the young males and females disclosed
in the nest quit it, and appear upon the surface of the earth ; here
they swarm in innumerable hosts, and pair. The busied workers then
convey a pair back into the dwelling, and imprison them in the central
royal cell, the entrances to which they decrease and guard. Through
these apertures the imprisoned pair then receive the nutriment they
require. The male now, as among all other insects, speedily dies after
copulating, but the female commences from this period to swell con-
siderably from the development of the eggs ; this swelling continues
until the time of her commencing to lay them, when her abdomen is
about 1,500 or 2,000 times larger than the rest of her body. During
the period of this swelling the workers remove the walls of the royal
cell, uniting the nearest cells to it, so that in proportion to the increase
of the body of the queen the size of the cell she inhabits is also
increased. She now commences to lay eggs during the constant undu-
lating motion of her abdomen, which exhibits the peristaltic motion of
the egg- ducts. The eggs are conveyed away by the workers as they
are laid, and conveyed to the distant rearing cells. It is impossible to
give the exact number of the eggs laid, but it must be enormous, which
is proved as well by the size of her abdomen as by the long time she is
laying them, as well as by the number she lays in a minute, namely,
sixty. In these nursery cells the larvae are first fed by the workers,
they afterwards intermix among the workers, and participate in their
destructive expeditions, which they make without any impediment, by
means of their subterranean passages to the vicinity of the substance
they purpose to destroy. Thus far extends the information of natu-
ralists who have travelled. They are silent upon the mode in which a
new colony is founded, and what induces the old ones to their forma-
tion, and we may, if we will not remain wholly dark upon the subject,
start the hypothesis that the communities of Termites, at the time

536

PSYCHOLOGICAL PHYSIOLOGY.

when the number of the inhabitants of a nest is too numerous to admit
of its accommodating them all, swarm in a similar manner to the bees.
But such a swarm would only consist of workers and soldiers, which
select at the time of pairing a couple from the numerous royal pairs,
and raise them to be the lords of the colony.

We terminate here with the consideration of this family, in which
the interesting facts of the earlier ones are again repeated, the descrip-
tion of the intellectual impulses that have appropriately been designated
as instinctive phenomena, as perfectly as a short outline will admit.
As anxious for self-preservation, and therein exhibiting especially its
intellectual functions, the insect steps forth into the series of inde-
pendent organic beings, and as still anxious for the conservation of
the species, it again quits this large community. It was requisite to
illustrate this result, already expressed in the introduction to the
second chief division, as concisely as possible, and therefore all facts
which remain more or less isolated were necessarily omitted. This we
could the more satisfactorily do, as another work, to which we have
here frequently referred, as well as below, has endeavoured to give a
similar solution to the same problem, yet with infinitely greater detail ;
we mean Kirby and Spence’s Introduction to Entomology, a book which,
for the animation of its description, fidelity of portraiture, and fulness
of facts, vainly seeks its equal, and will with difficulty be surpassed.
We will therefore refer our readers to it, who may here have observed
many defects, and none, we can assure them, will quit it undelighted
or without regret.

537

THIRD SUBSECTION.

RELATIONS OF INSECTS TO THE EXTERNAL

WORLD.

§ 300.

We have now become acquainted with both the corporeal and intel-
lectual natures of insects, and might therefore consider their general
natural history as concluded ; but having as yet left untouched one
portion of the history of the lives of these creatures, namely, their rela-
tion to the rest of organic nature, we will therefore appropriate a few
pages to the investigation of this subject. That the whole of organic
nature stands in close connexion together must be evident to every one
who has paid the least attention to the subject. When the plant dies it
becomes the parent of a thousand others, all chiefly indeed of lower
station ; the animal supports itself by deriving its nutriment from the
vegetable kingdom, and then itself supplies other animals, which are not
appointed to feed upon vegetables, with means of preservation. This
relation of insects to the vegetable kingdom and to other organisms will
form the immediate subject of our present investigation ; we shall
here class the conditions under which the insect continues in the
external world, in so far as it is only by this favourable relation that
that first object is attained, and these we distinguish as the places of
resort and the distribution of insects ; their geographical division should
form a component part of this chapter, and we may then devote our
attention to the insects of a past creation, concluding their general
history with this last inquiry.

538

TENTH CHAPTER.

INSECTS IN RELATION TO OTHER ORGANIC
BEINGS.

§ 301.

It is a proved fact that all animal bodies derive their nutriment
originally from the vegetable kingdom. In no class of animals is this
more evident to us than among insects. We have before seen, where
we spoke of the food of insects, that vegetable substances constitute
their chief subsistence, and that entire orders, as, for instance, the
Lepidoptera , from the first moment of their existence, feed upon
nothing but plants and their juices. In the innumerable multitudes
of different species, and the hosts of individuals of one species, this
might eventually prove injurious to the vegetable kingdom, if also
many insects did not likewise aid to promote the growth of plants.
This observation leads us to recognise the true relations of the insect to
the vegetable world, and whilst discovering this we perceive at the
same time the precise object nature accomplishes in its capacious
economy by means of insects. It is double ; in the first place to set a
limit to the preponderating increase of plants, and also, as such a rela-
tion might easily degenerate into their total destruction, it is also
careful, by another course, of preserving the vegetable kingdom.

The first object is attained by means of those insects which derive
their nutriment from vegetable substances, consequently by means of
those which devour leaves, flowers, wood, fruits, and their seeds. These
organs provide for the continuance of plants as individuals or species,
and every plant would more or less suffer if one or all of them were
totally destroyed by insects. Let us examine this more closely in indi-
vidual instances.

§ 302.

With respect to those insects which destroy the roots of many plants,
and thereby restrict their superfluous growth, we must remark, that it is
generally larvae only which feed upon that part. Among the Carabodea

INSECTS IN RELATION TO PLANTS.

539

the larva of Zabrus belongs to these, for in the spring of the year 1812,
in the vicinity of Halle, whole corn-fields were devoured by their vora-
city *. During the day it buries itself six inches deep in the earth,
and towards evening it comes to the surface, and then eats into the pith
of the roots, biting off the blade closely abo ve the ground. Thus in the
above year twelve hides of wheat, rye, and barley were destroyed. As
the genus Amara , which is closely allied to Zabrus , has in its perfect
state a very similar mode of life, particularlv the division of it known
by the name of Leirus , we may conclude that' their larvae also live
upon the roots of grass. We may perhaps also class here the larva
first described by Walfrod, and which he considered as a wire worm
(the larva of Elater segelis , GylL). Kirby and Spence t consider it
as the larva of a Staphylinus, but this is contradicted by the difference of
the mode of life of the other individuals of this tribe. It lives, namely,
at the roots of wheat, devours the just germinating grain, and in older
plants it consumes the root only. According to Sir J. Banks the same
larva destroys turnips, and sometimes from forty to fifty individuals
are found in one root.

In addition to these it is especially the larvae of many of the Elaiers
which attack the roots of corn and other plants. We know that the
wire worm, which is the larva of Elater segetis, Gyll., (E. lineatus,
Lin., E. striatus, F.), feeds upon the roots of corn, as well as that the
larva of the allied Elater obscurus, Lin., (E. variabilis, Fab.) feeds
upon the roots of almost all kinds of garden plants and culinary vege-
tables, and sometimes, in places where they have much increased, pro-
duce great injury.

The majority of the larvae of those Lamellicornes which in their per-
fect state feed upon leaves, as the Melolonthce and Cetonice, devour, in
that state, the roots of plants ; these thick, fat, yellowish white larvae are
well enough known to farmers, and frequently produce great injury to
corn. Multitudes of the larvae of Melolontha ruficornis actively par-
ticipated in the devastation committed by the larvae of Zabrus gibbus
in the vicinity of Halle. The more numerous and more generally dis-
tributed larvae of Melolontha vulgaris , the common cockchafer, are not
less injurious, particularly as they pass several years as larvae, and every
year new ones are produced. An instance occurred near Norwich, in

* Germar’s Mag. vol. i. parti, p. l,&c.
t Introduct. to Entom. iv. Letter xlv.

540

PHYSIOLOGY.

which all the fields of a farmer were entirely destroyed, and he and
his labourers collected eighty bushels of them. The larvae of Hoplia
pulverulenta, H. graminicola, and H. argentea, divell in humid mea-
dows, where they destroy the roots of the different grasses. Some few
years ago I myself discovered all the blades of high grass of this descrip-
tion completely covered with the perfect H. argentea.

It is especially among the Curculios that we find larvae which are
destructive to roots ; but less so among the other families, yet the larva
of Lathridius porcatus, according to Kyber *, feeds at the roots of
Rhaphanus sativus, and especially in that of the variety known by
the name of the radish. Kirby and Spence reared from a small larva
that was found in the root of Sinapis arvensis the Cur culio contractus ,
Msh., and the Rh. assimilis , Fab., two species of insects belonging to
the genus Ceutorhynchus , which, even as perfect insects, like all their
congeners, attack the young shoots of plants.

Besides the above larvae of the beetles, many of the maggots of the
Diptera are fond of the roots of plants. Thus the maggot of a fly has
been found in a carrot (the root of Daucus carota ), but it was not
reared ; in the radish (the root of Rhaphanus sativus) the maggot of
Anthomya radicum, Meig. ; and in onions a similar maggot, which pro-
duced a fly that Kirby and Spence call Scatophaga ceparum. Other
dipterous larvae Reaumur t found in the bulbs of the narcissus, and
reared from them a fly belonging to the family of the Syrphodea, which
Meigen calls Merodon equestris. The root also of the cauliflower feeds
the maggots of flies ; in that, as well as in the other varieties of the
cabbage, is found the maggot of the Tipula oleracea , Lin.

Although the majority of the caterpillars of the Lepidoptera feed
upon the leaves of plants, yet there are some which prefer their young
roots; thus the caterpillar of Noctua ( Episema , Tr.) graminis , Fab.,
which consumes the tender roots of the softer grasses, and spares the
elder harder ones, for instance, those of Alopecurus pratensis, Lin., as
well as those of corn and of the Trifolium pratense, Lin. J

§ 303.

Those insects, however, are more numerous which either bore into
the stems of plants or into the woody trunks of trees ; but their pre-

* Germar’s Mag. vol. ii. p. 1, &c. f Memoires, vol. iv. part xxxiv.

X Ochsenheimer Schmetterlinge von Europa fortges. von Treitsclike, 5 t. part i. p. 122.

INSECTS IN RELATION TO PLANTS. o4t

sence docs not in general so speedily occasion the death of the plant, as
the stem is a larger and less easily wounded organ than the root.

Among the beetles we may place here the several boring and bark
beetles that form the family of Deperditores (Xylotrogi, Lat.) and Bos -
trychodea ( Trogositarice, Lat.), as well as the large family of the Ceram-
bycina. The majority, however, destroy the woody substance of the stem
in general only when the tree is felled or already prepared for manipu-
lation, in the latter case especially it is attacked by those of the Deperdi-
tores, which belong to the genera P Linus and Anobium: they appear to
be created more for the dispersion of dead vegetable substances than
for the destruction of living plants. As Nature produces the more
rapid dissolution of corrupt animal matter, by means of the ontho-
phagous and carrion beetles, so it appears that she accomplishes the
same object with respect to the dead stems of plants, through the
agency of these insects. The larvae also of the Bupresiodea and of
many Elnlers live in the stem, for instance, the larva of Buprestis
biguttata in the stem of oaks, Elater rufus in the stem of pines, and
both especially in the remaining stumps of felled trees. There also do
we particularly find the larvae of the capricorns, and living trees they
do not appear to care for, yet the larva of Saperda linearis lives in
the pith of the young twigs of the stem of the hazel ( Coryllus avel-
lana ), and that of Lamia amputator in the pith of tropical plants *,
that of Callidium bajulus in timber, rafters, and roofs. But the family
of the bark beetles ( Bostrychodea ), thus named from their dwelling-
place, beneath the bark, are most destructive to woods, especially to those
consisting of firs, pines, and oaks, for example, the genus Platypus. The
commoner species, namely, Bostrychus typographies, B. laricis , Hyle-
sinus piniperda, Hylurgus ater, &c., occasionally so much undermine
the bark that it becomes quite loosened from the stem, and the tree,
having lost in its liburnum its nutritive layer, dies. Formerly manv
instances occurred of whole forests of pines being thus destroyed in the
Harz, in Franconia, and in Silesia, and it was called the (wurmtrockniszj
worm dry rot. Tropical trees are also visited by such guests, for
instance, the stems of palms by the Calandra palmarum, but they are
chiefly found in felled trees lying in the woods, and which they speedily
destroy through the great size they attain. It is thus also that the large
larvae of exotic capricorns live, as those of Prionus cervicornis, Pr.

Lansdown Guilding in I.innaean Trans, vol. xiii.

542

PHYSIOLOGY.

damicornis, Lamia tribulus, See., which live in the stems of Brazilian
or tropical plants, particularly those of the genus Bombax.

The stems of corn also serve as a dwelling-place for many larvae ;
thus we find the maggot of a fly belonging to the genus Mosillus, of
Latreille, subsisting in the blade of wheat. Another, known by the
name of the Hessian fly, also lays its eggs in the blade of wheat, and
thus frequently destroys entire fields, from the increasing maggot
devouring all the leaves. Musca pumilionis, Lin., lays its eggs in the
heart of young rye, and the larva destroys the shoot, commencing with
the germen and then consuming the leaf. Pyralis sicalis attacks in a
similar manner the blade of barley, depositing its eggs in a cavity bored
between the leaf and stem. Exotic grasses also are destroyed by
enemies which consume their pith. An ant ( Formica analis , Latr.)
makes its dwelling in the interior of the sugar-cane, and feeds upon its
sweet pith ; another ( F . saccharivora, Lin.), takes up its abode
between the cellular roots of the same plant, and thus destroys it by
drying it up. In the fortieth year of the preceding century this ant
had so much increased in the island of Granada that every plantation
was destroyed by it, and every means applied to remove the evil was
fruitless. The larvae also of the Elater noctilucus , of which we have
already spoken, lives in the pith of the sugar-cane, and feeds upon it *.

The larvae of many Lepidoptera live in the interior of the stems
and of the twigs, or beneath the bark, and thereby prevent the growth
of the plant : thus, for instance, we find the caterpillars of several
moths, as that of Tinea corticella, Fab., beneath the bark of trees ;
and another caterpillar, that of Tortrix Weberana, F., is the cause of
great injury to fruit trees, by boring through their bark. The cater-
pillar of Thyris fenesirina , O., lives in the annual twigs of the com-
mon Sambucus niger , L., and of Arctium lappa, and destroy their soft
pith. But the caterpillars of the genus Sesia are well known as
borers of the stems of trees, but from their small number we have never
heard of extraordinary devastations committed by them. Thus the
caterpillar of Sesia apiformis lives in the stems of all kinds of poplars,
as does that of S. asiliformis in the young stems of Populus dilatala,
L. ; S. spheciformis in the stems of the elders and birch trees ; S .
hylceiformis in the branches of Rubus idteus, L. ; S. culiciformis in the
bark of plum and apple trees; S. formic cef or mis in the branches of

* Humboldt, Essai sur la Geographie des Plantes, p. 136.

INSECTS IN RELATION TO PLANTS.

543

different willows, for instance, of Salix alba ; S. tipuliformis in the
pith of the stem of the red currant ( Ribes rubrum , Lin. *). It is,
lastly, very generally known that the caterpillar of the goat moth
( Cossus ligniperda ) lives for several years in the stems of old willows,
where by degrees it transforms the internal dead part into powder.

Among the other orders we are acquainted with the family of the
Sirices , which all live as larvae in the stem partly of pines and partly
of oaks, and there change into pupse, as well as individual genera of
bees, for instance, Xylocopa, which bores into wood, especially door-
posts and gates, and there forms cells for its young*. The same in
the Dipterous family of the Xylophagi, the larvae of which live in stems
beneath the bark.

§ 304.

The leaves of plants and their young germens or eyes are more
universally destroyed by insects. Among those which make the just
developing eyes their dwelling place are the larvae of the Tortrices and
the skip-jacks ( Hatticce ). Many plants are absolutely infested by these
inimical guests, and we frequently hear the gardener and farmer com-
plain of these terrible enemies of their fruit harvest, when they have
resumed their activity in the destruction of the young buds. The larvae
of the Tortrices fold up by their webs the just developed leaves, and
thus obstruct the younger ones, and then conveniently eat away the
innermost core of the eye, which in fruit trees consists especially of the
blossom buds. They do not appear to have any particular preference
among the different kinds of fruit, but attack all at the same time or
successively. The skip-jacks do not weave the leaves together, but
merely devour the young shoots. Among these also no species appears
to be especially restricted to one and the same plant, but choose
them at caprice. Yet H. oleracea and H. nemorum, being the most
common species, are the most notorious. The first especially attacks
young culinary plants, particularly those belonging to the family of the
Crucifera, namely, cabbage, turnip, mustard, rape, &c. H. concinna
lives in the young shoots and buds of the hop ; H. nemorum in the
turnip; and the remaining numerous species in the buds of wild
uncultivated plants.

The host of insects that destroy the leaves of vegetables is so innu-

Ochsenheiraer Schmetterlinge von Europa, vol. ii. p. 121, &c.

544

PHYSIOLOGY.

merable, that even a superficial account of our native plants, and the
insects that dwell upon them, would fill a volume : we will therefore
limit ourselves to the enumeration of the chief families that consume
leaves, and cite from them the most interesting genera. Among the
beetles we find the large family of the Chrysomela , both as larva and
imago, select leaves for their food, and they are therefore usually found
upon plants. Thus we find Galleruca tanaceti upon the Tanacetum
vulgare ; G. viburni upon Viburnum opulus ; G. nymphea upon
water plants Nymphea , Alisma, Sagittaria ; G. Alni upon Alnus
glutinosa ; Chrysomela pallida upon Sorbus aucuparia ; Chr. varians
and Chr. centaur ei, F., upon Hypericum perforatum ; Chr. Sophice upon
Sisymbrium Sophia L.; Chr. vitellince upon Salix vitellina ; Lema
Asparagi and L. Yl-punctata upon Asparagus officinalis ; Lema
merdigera and L. brunnea upon Lilium martagon, &c. All these
beetles and their larvae have the peculiarity of not in general consum-
ing the leaf from its margin, like the caterpillars of the Lepidoptera,
but they bite a hole into the substance, around which they continue to
eat. Thus both these destroyers may be distinguished from each other
by the appearance merely of the leaf that has been attacked. Other
families of beetles do not restrict themselves so exclusively to leaves,
' yet many, for example, the Malacoderma , Melolonthodea , Vesicifica ,
the Cassidce (particularly the larvae) and other genera devour leaves by
preference.

Of the remaining orders it is, especially in that of the Hymenoptera
and among the family of saw-flies (T enthredonodea) , that we find leaf-
devouring insects. The pseudo caterpillars of these insects, deposited
even by the mother as an egg in the parenchyma of the leaf, devour the
leaves with incredible voracity, and thereby frequently destroy entire
plantations. Thus the large larva of Cimbex variabilis lives chiefly
upon willows, of C. lucorum upon the birch, of Hylotoma rosce upon
roses, of the different species of Lophyrus upon different pines and
firs, L. pini, for instance, upon Pinus silvestris, of L. laricis upon
Pinus larix, &c. The true saw-flies ( Tenthredo ) are the most numerous
of all, and destroy cherries ( Prunus cerasus ), alders {Alnus glutinosa),
willows ( S . alba, S. caprcea , and many others), roses ( Rosa canina ),
and many other plants. Where they are numerous upon a tree they
speedily destroy all the leaves, and the tree, already sickly from the loss
of its organs of respiration, dies. Thus, one known by the name of
the slug-worm, living upon the plum, some few years ago destroyed

INSECTS IN RELATION TO PLANTS.

545

whole' districts of orchards* as Peck has related in a distinct treatise *.
The larva of Lyda pratensis also, which lives upon the fir, a short time
since, in the vicinity of Muskau, in Silesia, committed dreadful devas-
tation, according to the communication of K. Hapf +.

But in no order are leaves used so universally for food as among the
Lepidoptera, of which the majority as caterpillars consume them. We
imagine we shall give a sufficient proof of this by mentioning some of
the numerous trees and plants indigenous with us, and which are
eaten by caterpillars. The oak, in the first place, feeds innumerable
caterpillars, for instance, Gastropacha quercus, Smerintkus quercus,
Harpya Milhauseri , Nolodonla camelina , innumerable Noctuce, and
Geometers ; according to a calculation of Roesel’s, this tree supports
in its several parts and organs about two hundred distinct species of
insects, whence it will be easy to deduce their relation to the rest, as
well as of insects to the vegetable kingdom in general. Thus every
forest tree has not merely one, but three, four, and even as many as a
dozen caterpillars which feed upon its leaves, and which often seriously
injure them. We will merely refer to the destruction occasioned by
Liparis dispar to poplars, L. salicis to willows, L. chrysorrhea , L.
nudibunda , E.fascelina to different fruit trees, L. monacha to the fir,
and a multitude of others, which are known as tree and forest de-
stroyers. The number of injurious forest caterpillars is so large that
we cannot wonder at the great devastation we so frequently hear com-
mitted by them. Thus there are found upon the pine, besides those
already enumerated, Gastropacha pini , G. pityocampa, Sphinx pi -
nastri, Noctua ( Trachea , Tr.) piniperda , Lilhoria quadra, Geometra
( Fidonia , Tr piniaria, G. ( Ellopia , Tr.) prasinaria, G. (Ell. Tr.)
fasciaria ; Tinea resinella, which occasions the escape of resin from the
young twigs of the fir ; T. dodecella, T. strobilella, T. pinella, &c.,
which dwell partly in the young buds, and partly in the eyes of the
firs. We will not extend this list to other forest trees, but refer at
once to Bechstein’s ;{; Natural History of Injurious Forest Insects,
where there is ample detail. We will only further mention that many
of our fruit trees support their peculiar enemies, among which the cater-

* W. Peck, Natural History of the Slug-worm. Boston, N. A., 1799. 8vo.

f Bemerkungen über Raupenfrass v. K. Hapf. Bamberg, in Aschaffenberg. 1829. 8vo.

£ Bechstein’s Naturgeschichte der schädlichen Forstinsekten. Leipzig, 1805, 3 vols.
4to.

N N

546

PHYSIOLOGY.

pillars of Gastropacha neustria and Episema cceruleocephala are the
most common and the most dangerous.

The different kinds of corn, as well as the grasses in general, are
less attacked by leaf-devouring caterpillars, yet the caterpillar of
Episema graminis has been observed to destroy them *. The numerous
members of the order of the Orthoptera feed very generally upon these
plants, but they do not despise even others. Thus the grasshoppers
can be fed with all kinds of leaves, but they seem to prefer those of
grass to all others. One insect of this order, the migratory locust, has
acquired a widely dispersed notoriety from the devastating expeditions it
undertakes in immense hosts, and it has thence been unjustly considered
as an introduced insect. This it is certainly not, it being indigenous with
us (Germany), and it is only occasionally that it appears in vast hosts,
which quit their birth-place from having there destroyed all their
vegetable food, and they proceed further to seek fresh. We will refer
to Kirby and Spence for a full account of their mode of migrating, as
well as for the details of their several excursions, and merely mention
that an instance of this occurred in June, 1832, near the Bavarian town
Weissenburg. They passed from east to west over the town, in some
places but a few ells above the surface, and their number was so great
that it took three quarters of an hour for the entire swarm to pass.
Wind and rain, which speedily came on, adds the informant, prevented
further observation t.

These remarks sufficiently prove how many insects derive their food
from leaves, and how great the destruction is when their numbers dis-
proportionately increase : we will now proceed to notice those insects
which attack by preference the fruit and stem.

§ 305,

Upon returning to the order of the Coleoptera , we immediately find
a large family among them which are chiefly occupied with the destruc-
tion of the seeds of plants, namely, the Curculios (Rhynchophora) . The
majority of the species have their peculiar plants upon which they live,
and in the fruits of which they are found as larvae. In the large genus
Bruchus , which is the nearest allied to the Curculios , all the species
whose transformations we are acquainted with live as larvae in seeds.

* Germar’s Mag. vol. iii. p. 433.

•f Vossische Berliner Zeitung for the 21 June, 1832.

INSECTS IN RELATION TO PLANTS.

547

Thus, in the pulse of the pea (Pisum sativum) the larva of B.granarius
dwells, devouring the seed. In North America the same plant is attacked
by another species, which is also sometimes found with us, namely,
Br. Pisi . A third, the Br. pectinicornis, destroys peas in China. And
a fourth species, perhaps Br. scutellaris F., attacks the seed of a pulse
( Phaseolus or Dolichus) in India, which is called by the natives Koloo ,
and by the English Gram. A very large species, native to South
America, Br. rußcornis , Germ., lives in the kernel of the cocoa-nut,
and is sometimes even found in it in Europe * ; and Br. nucleorum ,
according to Fabricius (Br. bactris, Hbst.), is found in the same fruit.
Another genus, Apion , Hbst., has the same habits. We find the
numerous species of this genus upon the plants in the seeds of which
the larva lives, for instance, Apion flavofemoratuvn , Kirb. ; upon
Trifol patense , Lin. ; Ap. Ulicis , Kirb. ; upon JJlex Europceus, Ap.
vernale ; upon Ballota nigra , L., and Lamium album , L. Ap, ceneum ;
upon Alcea rosea, Lin. Ap. frumenlarium in the seeds of corn. The
larva of this beetle, known by the name of the red corn worm, frequently
causes great injury in granaries: it consumes the farinaceous portion,
and leaves the case untouched. But the black larva of Calandra
granaria , which is frequently found in houses, granaries, &c., is even
more injurious. A second species of this genus Cal. Oryzce we fre-
quently find among rice. The third enemy to corn warehouses, known
by the name of the white worm, belongs to the order of the Lepidoptera,
and is the larva of Tinea granella. We might considerably enlarge
this list were we to enumerate all the Curculios injurious to seeds, but
we will merely remark that it is particularly the smaller species which
appear to prefer this food. Thus the genera Balaninus and Antkonomus
are known as attacking nuts and stone fruits. The larvae of B. nucum
live in the common hazel nut, and that of A. druparum in the stones
of the sour cherry. The smaller Ceutorhynchi all dwell upon plants,
and doubtlessly feed upon their seeds or leaves. The Cioni attack the
species of the genus Verbascum, and live in the stem beneath the
epidermis. Very many other Curculios live similarly in the substance
of plants. Thus, the larva of Lixus paraplecticus lives in that of
Phellandrium aquaticum , and of Cryptorhynchus Lapathi upon Rumex
hydrolopathum, Lin. &c.

Among the other orders it is especially the Lepidoptera and Diptera

* Germar’s Mag., vol. iii. p. 1, &c.
nn2

548

PHYSIOLOGY.

which, as larvae, live upon fruits. Among our fruits, the plum, apple,
and pear are attacked by a small moth. Tinea ( Carpocapsa , Tr.)
pomona, and which, although it does not destroy the propagative powers
of the seed, yet it renders the fruit disagreeable to us. Thus another
caterpillar of a moth attacks the fruit of the chestnut (Castania vesca),
and destroys, by causing the fruit to fall before it is ripe, a rich and
profitable harvest. The date also is destroyed by a larva which
Haselquist observed, and refers it to the genus Dermestes, but certainly
incorrectly. Another larva of a moth, Pyralis fasciana, F., lives in
grapes, and destroys the most beautiful and largest grapes. But not
this only attacks the vine, but many other insects in different countries.
Pyralis vitana , F., as larvae, devour the leaves. In the Crimea, the
larva of a Zygcena attacks the young shoots as well as the larva of
Eumolpus Vitis , F., and of Rhynchites Bacchus, Herbst. In Silesia,
in the vicinity of Grünberg, where the vine is extensively cultivated,
Thylaciles geminatus, Germ., is a destructive enemy to young shoots,
as it entirely consumes them immediately upon the budding. Lethrus
cephalotes does the same in Hungary. In southern countries where
the vine is cultivated, a species of Coccus sometimes destroys the entire
vintage by sucking the young shoots. A caterpillar also lives in the
fruit of the olive, which destroys the kernel and produces Tinea
oleella, F. A second larva lives in the same plant, that of Oscinis
olece, Lat., an insect belonging to the family of the flies, whose nearest
ally, namely, Dacus Cesari, and the species of the genus Tephritis ,
follow a similar mode of life. Tephr. cardui especially attacks thistles
and burdocks, and partly lives in the pith of the stem and partly in
the fruit and flower which it then distorts. Other dipterous maggots
distort plants by gall-shaped excrescences, for instance ; the genera
Cecidomya, Lasioptera, &c. One of these maggots especially attacks
the ripening ears of corn, and thereby occasions great destruction.
Kirby has described this fly by the name of Tipula tritici *.

§ 306.

We will now drop the thread of our inquiry into those insects which
are injurious to plants or which restrict their superabundance, convinced
that the instances adduced above sufficiently prove a strong relation
between plants and insects. We must now prove, on the opposite side,

* Lin. Trans., vol. iii. p.243 — 245; vol. iv. p. 224 — 239; and vol. v. p. 96 — 110.

INSECTS IN RELATION TO PLANTS.

549

that very many insects quite unconsciously promote the growth and
advance of them.

If we inspect the organisation of those parts of plants upon which its
further existence as a species depends, namely, the sexual organs, we
shall speedily observe that their position is such, that, without extra-
neous means, the male seed could not reach the female organ. Thus,
therefore, in all plants which, without such assistance, could not be
impregnated, the procreation of new individuals by the planting of a
ripe seed is rendered almost impossible, and would also in fact but
seldom occur, were it not for the intervention of insects. A great
number of insects, therefore, namely, all the Lepidoptei'a, the bees,
wasps, ichneumons, the majority of Diptera, and many beetles find their
food either in the pollen itself of the plants or in the honey juices
secreted by the nectaries, and for this purpose they visit flowers to
procure their food from them. In these visits made without care for
disturbing the parts of flowers, or mixing them together, they convey
the farina which has burst from the anthers to the stigma of the female
pistil, and thereby cause impregnation. This relation, for the observa-
tion of which we are indebted to the venerable Ch. K. Sprengel *,
perfectly explains to us the relative connexion existing between plants
and insects. To obtain at some period this object, the plant, by great
self-sacrifice, and, indeed, with sometimes the loss of its own life, has
nurtured the insect within its bosom, and fed it with its own juices,
and, what it is not enabled to attain individually, being destroyed by
its enemy which it reared as a friend, it conveys over to its congeners.
We may possibly be misunderstood in thus speaking of the reciprocal
relation existing between plants and insects, as insinuating a species of
consciousness of their calling and a recognition of their duties } for it is
not the plant or insect that thinks or reflects, but Eternal Wisdom has
felt and thought for them, and has so strengthened their mutual attach-
ment, that the human mind in explaining it may well illustrate it as
affection and friendship, and as a recognition of what the one is indebted
to the other, and what it may thence expect in return, thereby
exhibiting the infinite love distributed throughout the universe t.
But we are diverging from the path of facts, to which we shall

* Das Entdeckte Geheimnisz im Baue und der Befruchtung der Blumen. Berlin,
1793. 4 to.

t See Burdach’s Physiologie, tom. i. p. 322 and p. 399, &c.

550

PHYSIOLOGY.

therefore return; further explaining this reciprocal relation in indi-
vidual instances.

Very many, indeed we may say the majority of plants are furnished
with nectaries which secrete a honey, which many insects, particularly
the Lepidoptera and bees, seek very greedily. To procure this honey,
those insects fly, some by day in the sunshine, and others in the twilight
from flower to flower, visit each, and here for a time imbibe the freshly-
secreted juices. They cannot avoid sweeping off the farina that has
just escaped from the anthers with their rough hairy bodies, and which
they bring into contact with the stigma, for both organs must frequently
be pushed on one side by the insect visiting the flower before it can
reach the nectaries. Some observers have remarked that insects are
very particular in the selection of flowers, and at one flight visit but
the blossoms of one kind of plant. This, according to Ch. K. Sprengel,
occasions the impregnation of flowers, for in the majority of flowers the
anthers and stigma have not the same degree of ripeness, but either the
one or the other is the earliest. As insects visit only flowers of the same
species, they now meet with those that have ripe anthers and now with
those with ripe stigmata, and cause impregnation by bringing the ripe
pollen into contact with the ripe stigma. Also, as Kölreuter has
already remarked, and later observations have tended to confirm, the
majority of flowers cannot be impregnated by their own pollen, but
require that of other individuals, just as the hermaphrodite Mollusca
require a mutual connexion, and cannot impregnate themselves ; and if
this law be general, which, however, does not appear to be the case,
insects alone can be the means by which nature attains the full object
of plants, namely, their impregnation and formation of seed.

If in many cases by other means, namely, by wind and rain, both of
which shake the flowers, and thus bring the pollen into contact with the
stigma, impregnation is effected, yet in very many it appears to be
possible only through the assistance of insects. This is the case in
dioecious plants, namely, in the sallows and poplars, which blossom
early in the year. In these also the male flowers are the earliest, the
female ones the latest ; both contain nectaries, and are therefore much
visited by bees and flies. It is only thus that the female flowers can
be impregnated by means of the pollen hanging to the insect. This is
the case also with the dioecious palms, namely, in Phcenis dactylifera,
the male of which is the rarest in its country, and is frequently at
many miles distance from the female. Also many monoecious plants.

INSECTS IN RELATION TO PLANTS.

551

in which, as in Ricinus, the female parts are above the male ones, can
therefore be only thus impregnated. The same in the whole family
of orchideous plants, in which indeed the anthers are placed above the
stigma, but frequently consist of a viscid waxy mass, whence the pollen,
upon the shaking of the plant, cannot fall upon the stigma, but only
by means of insects which visit the plant, and who smear themselves
with this clammy substance, can it be rubbed upon the stigma. The
Aristolochia clematitis , in which there is also observed a growing
together of the filaments with the style, is impregnated by a little fly
peculiar to it, the Tipula pennicornis , Lin., and which belongs to
Meigen’s genus Ceratopogon . This little creature creeps through the
tubular portion of the flower into the lower cavity where the nectaries
are placed, but cannot return back, — hairs placed in that direction pre-
venting it. Whilst it now flutters about for several days until the
flower fades, it brings the pollen into contact with the stigma, and thus
causes impregnation. It appears also that other plants require certain
species of insects to facilitate their impregnation ; and it may originate
thence that so many exotic, and especially tropical, plants, produce no
seed in our hot-houses, as they have not the peculiar insects requisite
to promote it. This appears to be confirmed by the observations
made upon indigenous plants, namely, upon Nigella arvensis, Iris
xiphium , and the species of Antirrhinum, that they are also visited
by insects of only one species or of one genus, and therefore more
frequently remain unproductive than others to which many insects
resort, as the Umbellala, Syngenista, &c. Many insects, namely, bees
which live solitary, and especially the males, pass the night also in
flowers, for instance, Chelostoma truncorum , Labr., which reposes in
the large Campanula with pendent flowers. In these visits they like-
wise must bring the pollen into contact with the stigma. The
Syngenistce, in which the stigma in general projects far above the
coronet of anthers, are visited by innumerable small beetles, particularly
Nitidula cenea and the Thripes, which creep down into the recesses of
the flower, and naturally upon their return touch the stigma with their
body covered over with pollen, whence arises, as we have before
remarked, the great fertility of these flowers.

These remarks may suffice as a proof of the reciprocal relation
between plants and insects. A more detailed account of it may be
found in the book that we have before referred to of Ch. K. Sprengel.

552

PHYSIOLOGY.

§ 307.

With respect to their relation to other animals, it is probable that
none takes place between them and the lowest in the scale, as the
majority of the latter dwell in water, whereas insects are air-animals.
The lower animals also are especially found in the sea, which no insect
inhabits. The lower fresh- water animals are partly too small to supply
insects with sufficient food, and partly again too large to be conquered
by the rapacious water insects. Yet I have sometimes observed leeches
( Hirudo vulgaris and species of Clepsini ) in the power of the large
Dyiici. We may also admit that these water animals exercise the
right of retaliation, and also devour small insects, at least those among
them which are appointed to feed upon animal matter ; yet they would
doubtlessly offer but little nutriment to the leeches, as these seek the
blood of the vertebrata. Nor do insects appear to stand in any very
near relation to the Mollusca , particularly as the majority of these
inhabit the sea. The larvae of many insects may serve fresh-water
snails as food, whereas the land snails, which feed upon vegetable sub-
stances, are attacked by many insects which as larvae live parasitically
upon them. Mielzinsky first discovered the larva and apterous female
of JDrilus flavescens in the shells of snails in the vicinity of Geneva,
and described it under the generic name of Cochleoctonus. Subse-
quently Victor Audouin and Desmarest made further observations
upon this parasite, which is not rare upon Helix nemoralis , and
explained its development to the perfect insect *. The larvae also of
the Lampyri, which are closely allied to the genus Drilus , live parasi-
tically in snails, as Audouin has communicated f. A third insect, the
maggot of a small fly, the perfect state of which, however, is not known,
is said to live as a parasite in the body of the garden snail, and even to
show itself in its feelers. These are the only instances hitherto known
of insects living as parasites upon Mollusca. ,

But we find the relation of insects to other articulata, namely, to
the Arachnodea and to other insects, much more common. The
Crustacea almost all live in the sea, and are therefore secured from the
attacks of insects, and no parasitic insects have yet been found upon
the Myriapoda and wood lice. The spiders are also free from their

* Annales des Sciences Nat,, tom. i. p. 67 ; tom. ii. p. 129 and 443.

■f* lb. tom. vii. p. 353.

INSECTS IN RELATION TO INSECTS.

553

attacks, but not insects from tlie spiders, for almost all of the latter
feed upon insects only. Indeed there are no parasitic spiders, for they
are all absolutely animals of prey, which capture insects either by
cunning or by nets, they then kill them, and suck out all their
nutrimental juices. A great portion of the Acari, however, are parasitic
upon insects, and not, indeed, as we find the parasitic Acari upon
birds and Mammalia , beneath the epidermis, but upon it, and chiefly
where a delicate connecting membrane binds two plates together.
We thus find Gamasus coleoplratorum especially upon the dung and
carrion beetles, namely, Necrophorus, Scarabceus, and the Histers ;
several of the Trombidia upon different winged insects, namely,
Libellulce , gnats, aphis, &c., and Qcypela rubra , as a small cochenille
spot, upon several also often very small Diptera, and, lastly, the genus
Aclysia, even upon the water-beetles. They dwell also upon their
connecting membrane, and are besides enveloped in a peculiar case,
whence through a particular aperture the creature projects its mandibles,
and bores into the skin of the beetle *.

Much more numerous are the relations, considered from our present
point of view, in which insects of different families stand to each other.
We might assert that the predaceous beetles and those which live upon
animal substances, carry on as it were a war against those which feed
upon vegetables, and upon which they feed with the same voracity as
the latter do upon plants. Some, as the Carabodea, Dytici, and
a Stapkylini, do this, particularly in their perfect state, hunting down
the larvae of the herbivorous ones, and devouring all that they can
catch ; whereas others, and these especially are the most dangerous
enemies, seek to lay their eggs in the bodies of the larvae, thus presenting
their young with food in the body of a living creature. We find this
habit among the Ichneumons and the Tachince. Both select for this
purpose almost exclusively the caterpillars of Lepidoptera , and as a
caterpillar thus pierced must sooner or later die, they therefore consi-
derably restrict the influence such caterpillars have, by the destruction
of plants, upon the advance of the vegetable kingdom. The larvae of
the minute Pteromali live in a similar manner in the bodies of the
Cocci and Aphides , the influence of which is not less upon the de-
crease of the vegetable kingdom than that of the caterpillars of the

* Viet. Audouin in M£m. de la Soc. d’Hist. Nat. do Paris, tom. i. p. 98, PI. V. f. 2.
-—Diet, des Sc. Nat. Art. Aclysia.

554

PHYSIOLOGY.

Lepidoptera. Many of them also live in the caterpillars of several
butterflies. We cannot yet determine with certainty whether these
enemies of the vegetable feeders are as select in the choice of particular
insects as the latter are in the choice of their vegetable nutriment ; yet
this appears to be the case among the larger Ichneumons. Thus, for
instance, Ophion amiclus, Fab., lives upon the caterpillars of Sphinx
pinastri , Ichneumon lapidator in those of Noctua Typhae. The large
families of Sphecodea and Crahronea also destroy the larvae of
Lepidoptera to use them as food for their young, as we have frequently
before mentioned. It is remarkable that all these enemies of other
insects belong to the order of the Hymenoptera , of which we already
know that its members, by visiting flowers, contribute directly to the
advance and increase of the vegetable kingdom. We have now, there-
fore, also seen that they even go still further in promoting this, as they
destroy and remove insects inimical to plants. This double function
we perceive also in the majority of the Diptera , in as far as these in
their imago state visit blossoms, but as larvae thrive frequently in or
upon insects that feed upon vegetables. These two orders it is,
therefore, especially, which exhibit to us the closest connexion of insects
to the vegetable kingdom, as they in a double manner promote the
increase of plants.

§ 308.

With regard to the relation of insects to the vertebrata, we may
observe, that the same holds good with respect to fishes as what we
have observed upon the Mollusca. By their living especially in water
and in the sea, they are removed from the direct influence of insects,
and only those fishes which inhabit fresh water appear to lie in wait
for the larvae of the Ephemerae, Semblodea, Lihellulce , and gnats, and
use them as food. It has not yet been observed that insects are
parasitic upon fish, yet the larger Dytici and other water-beetles doubt-
lessly feed upon the spawn of fishes, and even Dyticus latissimus, as
well as its larger congeners, attack small fishes and eat out their eyes.

Nor do the reptiles either supply insects with food or serve them to
dwell upon, unless, which is very probable, the spawn of frogs is fre-
quently consumed by the large predaceous water beetles. These
beetles also frequently devour the little tadpoles, whereas insects supply
the reptiles that live upon land, namely, the frogs, salamanders, lizards,
and small snakes, with their sole and favourite food.

INSECTS IN RELATION TO BIRDS.

555

The relation between insects and birds is somewhat different. This
class, which we have found analogous to insects in their type of organ-
isation, overlooking their internal skeleton, stand in the closest relation
to insects. This relation is double, as we find insects deriving their
food from birds, and birds again feeding upon insects. With respect
to the first, there is probably not a single bird which is not inhabited
by one or even several clearly distinct species of parasitic insects, and
which even sometimes belong to distinct genera. All these insects
form a peculiar large group among the parasites, which Linnaeus classed
with the lice, but which De Geer, from their mandibulate oral organs,
separated by the name of Ricinus , from the lice ( Pediculus ), and
Nitzsch, lastly, collected together in a separate family which he called
Mallophaga (fur destroyers), and classed with the Ortkoptera . Their
most correct situation is perhaps amongst the Dictyotoptera, with
which we formerly placed them. This group falls into four very
natural genera, of which Philopterus and Liotheum are the most
numerous, and are distributed among all species of birds ; Trichodectes
and Gyropus are the smallest in number, and are found only upon the
mammalia, namely, upon beasts of prey, the Glires and the Rumi-
nantia, they dwell between the softer down or woolly hairs, and feed
upon that and not upon the blood of the animal, at least Nitzsch found
in all those which he anatomically investigated portions of down in
their stomach *. Besides this large group there are smaller genera and
species, which likewise live as parasites upon birds, especially upon
young nestlings, particularly the genus Camus , discovered by Nitzsch,
upon young starlings, a form allied to the Conopica , as well as the
genera Ornithomya , Lat., and Strebla , Wied, both of which belong to
the pupiparous family of the Diptera , which are found upon other
young birds, especially swallows.

Insectivorous birds are those chiefly which belong to the Passerines
and the Cuculines. The Laniadce feed almost exclusively upon insects,
but some are said also to prey upon small warm-blooded vertebrata.
The Coraces , or crows, devour chiefly carrion, but also very many feed
upon insects, namely, the jays and blackbirds ; some also eat fruits, which
we find likewise in the true singing birds. The genera Fringilla , Em-
beriza , Tanagra , and Euphone eat fruits and seeds ; Sylvia , on the

* See Nitzsch über die Familien und Gattungen der Thierinsekten, ln Germar’s
Magazine, vol. iii. p. 261.

556

PHYSIOLOGY.

contrary, Motacilla, Anthus, Certhia, Muscicapa, and Hirundo, de-
vour insects only, namely, flies and larvae. Among the Cuckoos it is
especially the large genera of Cuculus and Picus which attack insects,
and Upupa, Epimachus, Merops, and many exotic ones; whereas the
genera Rhamphaslus, Buceros, and Psittacus prefer vegetable food,
particularly fleshy fruits, to insects, and therefore feed chiefly or exclu-
sively upon them. We besides find among the snipes many genera
which feed upon insects and preferably upon their larvae, for instance,
Ckaradrius, (Edicnemus, Scolopax , Tringa , and Totanus, particu-
larly their smaller species ; the other waders and water birds prefer
to insects as food the amphibise, molluscae, fishes, and other marine
animals.

§ 309.

We find a similar relation between insects and the mammalia. Many
of them are inhabited by parasitic insects, which either belong to the
already mentioned genera Trichodectes and Gyropus among the Mai lo-
pkagi, or come under the genus Pediculus, peculiar to the mammalia.
The genus Pulex also lives principally upon the mammalia. Among
these also may be classed the pupiparous genera of the Diptera, which
family is also distributed upon both classes, yet only upon individual
species, and lastly, the family of the (Estrodea , which is peculiar to
the mammalia. Trichodectes and Gyropus likewise devour the soft
woolly hair of the mammalia, and perhaps also their epidermis ; whereas
the lice, by means of their hooked proboscis, which they thrust through
the integument, suck their blood. Many species of them are found
upon very many mammalia, for instance, upon the Glires, Ruminantia,
and swine, but not upon all. The genus of the flea is parasitic only
in its perfect state, as a larva it lives in putrid substances, especially
in dirty sleeping apartments, in the stalls of animals, &c. The flea
lives upon men, bats, beasts of prey, Glires, and they have even been
found upon pigeons and swallows ; they were all formerly classed under
one species, which Linnaeus called Pulex irritans , but they have since
been correctly separated into several species and characterised, as is
usual among parasites, according to the animal they inhabit. I have
myself only yet closely examined the flea of the rat, and I have found it
distinct from that of man. Among the Pupipara , the genus Hippo -
hosca ( Nirmomya , Nitz.), of which only one species, the H. equina , is

* J. F. Stephens1 Catalogue of British Insects. Lond., 1829. 8vo. Part 2, p. 328.

INSECTS IN RELATION TO MAMMALIA.

557

known, inhabits the horse, particularly beneath the tail and in the
softer parts; the genus Melophagus, Lat. ( Melophila , Nitzsch), is also
only known by one species, the M. ovinus, which inhabits the sheep,
among the downy hair ; the only species of the genus Lipoptena, Nitz.

( Melophagus , Autor.), namely, L. Cervina ( Pediculus cervi, Autor.),
frequents the different species of deer, and the genus Nycteribia the
bats, particularly the membrane of the wing.

The remarkable family of (Estrodea , of which we have before made
frequent mention, live in their larva state parasitic upon the hoofed
quadrupeds, especially the Ruminantia, and they quit the animal when
they change into pupae : this takes place in the earth ; but the flies,
which must be numerous, to judge from the multitude of larvae, are
seldom visible ; and we are as yet ignorant upon what they live. But the
parasitic larvae are deposited by the fly upon the skin of the animal as
eggs, and bore through it when, as is the case with (Estrus bovis and
( E , tarandi , they live beneath the epidermis ; or if they live in the
viscera of the animal they are conveyed in either by suction or licking.
The animals most subject to them are oxen, whose skin this fly pierces
and deposits its egg therein, the larvae here cause swollen excrescences,
from which their tails project, that they may respire. Another species,
the- Gastrus pecorum, lives, according to Fabricius, in the intestines of
oxen. The sheep is still more tormented, which receives a species
( CEstrus ovis ) into its nostrils and temporal cavities. The giddy sick-
ness of sheep, which has been attributed to this larvae, may doubtlessly
be more correctly ascribed to the worm ( Coenurus cerebr alls') living in
its brain, whereas these larvae are the cause of the sneezing, from which
many sheep suffer in summer. But the horse is chiefly annoyed by
these parasites : one species, the Gastr. nasalis, dwells in its oeso-
phagus ; a second, G. equi, and third, G. salutarius, in its stomach ; a
fourth (G. hcemorrhoidalis ) even in the colon. The larvae hang here,
holding by means of their hooked mandibles, in rows, and look like
thick, blunt, long cones, which are surrounded at the apex by many
rows of spines, and at the base have two kidney* shaped horny laminae
at their stigmata. The deer besides is tormented by the CEstri ; one
species, CEstrus tarandi, lives beneath the skin of the rein-deer, like
CE. bovis in the ox, whereas CE. trompe inhabits the temporal cavities
of the rein-deer. This fly is also found in Saxony, so that it is probable
that it also inhabits other species of deer. It is certain that Estrus
lineatus, Meig., which, according to Schrank, hangs from the superior

558

PHYSIOLOGY.

gums of the deer, as well as Gastrus nasalis , attacks, besides the
horse, likewise the ass, mule, deer, and goats. Beyond Europe we
also find several species, one of which, Trypoderma cuniculi, Wied,
(CEstrus cuniculi , Clark) lives beneath the skin of North American
hares and rabbits. CEstrus buccatus, Fab., and Musca Americana,
Fab., likewise belong to this genus, established by Wiedemann, and
without doubt live in a similar manner. The genus Colax, Wied.,
which is native to the Brazils and Java, admits of presuming a similar
mode of life, from its affinity to them.

The mammalia, which feed upon insects, are less numerous than the
insectivorous birds. We will enumerate as such the smaller Makis,
for example, the genera Stenops, Otolicnus , the last of which lives
especially upon grasshoppers; the majority of indigenous bats, the
shrew, the hedgehog, mole, and the other genera belonging to th eferis
insectivori. Besides, very many of the Edentata, namely, JDosypus and
Manis , feed upon insects. The species of the allied genus Myrmeco-
phaga, devour only ants, which they lick up with their long vermiform
tongue, like the woodpecker among the birds.

§ 310.

There still remains, as the subject of a short notice, the relation
existing between insects and man. The human body, like that of the
mammalia, serves as a residence for several parasitic insects. The best
known and most generally distributed parasites are the lice, four
species of which man nurtures in different parts of his body. The
most numerous of these is the head louse ( Pediculus capitis), which
lives in the hair of the head of many children, and of such adults who
are not clean, where it pierces the skin and sucks the blood. It prefers
the inclined parts of the head, and especially the back of the head,
where it deposits its eggs (nits), which are little pear-shaped bodies,
which it fastens to the base of the hair by means of a clammy substance.
The clothes louse ( [Pedic . vestimenti, De Geer), which differs from the
head louse by its larger size, more slender form, and by having black
spots upon the sides of its body, dwells upon the whole surface of the
body, but not upon the head, preferring particularly the breast and
back, and is less general than the former, and only found in very dirty
people among the lowest classes ; it is exceedingly abundant in Poland
and Russia. It lays its eggs at the base of the small hairs of the skin,
and conceals itself upon the skin and in the folds of the vestments. A

INSECTS IN RELATION TO MAN.

559

third species, the louse of Phtliriasis ( Ped . tabescentium) , which is the
nearest to the two preceding, has longer antennae, a larger and more
distinctly separated thorax, and an indistinctly ringed abdomen, espe-
cially at the sides ; at its apex there are four strong setae. It only
originates with Phthriasis, and lives like the former upon the skin at
parts where folds are formed and much perspiration collected. It has
been recently observed by Alt, in Bonn. * The fourth, or Ped. pubis,
Lin., has a contracted body, a very broad thorax, short thick legs, and a
two-pointed abdomen, it being emarginate at its apex. It is found
amongst the hair of the arm-pits and of the pubis, and sometimes
even in the eyebrows, and is also found only amongst dirty people.
According to Fabricius t the louse of the Negro is a fifth specifically
different species peculiar to mankind. It is black, and has a large, flat,
triangular head, two-pointed in front, and a wrinkled uniformly black
abdomen.

Next to the louse the flea is the most general parasite upon man ;
yet, as we have already mentioned, it is parasitic only in its perfect
state, and accompanies man by day and by night, tormenting him with
its painful punctures. Children and girls are particularly annoyed by
it. That the flea of man is of a peculiar kind recent observations have
made probable. A second species of the genus Pulex, the cbique,
pique, jigger , nigua , tungua ( Pulex penetrans, Lin.), is found in
America, and nestles in the flesh beneath the nails of the toes, where it
deposits its eggs. It thus speedily raises such swelling and irritation
that if the dangerous enemy be not speedily removed inflammatory
swellings originate, which quickly affect the whole limb. If, as some
observers have remarked, this creature does not pass through a perfect
metamorphosis, it will, notwithstanding its resemblance to the flea, not
belong to the genus Pulex, but must form a distinct genus of the
Hemiptera, in the vicinity of the lice. Pediculus ricinoides , of
Fabricius, is, without doubt, the same creature, and, from the informa-
tion he had received of its imperfect metamorphosis, was placed by him
among the lice J.

Besides the flea, the bed bug ( Acanthia lectularia, Fab.) is known
as a parasite of man. It is found in the joints of bedsteds, and is
not rare, especially in large towns, and when once they have nestled

* Alt Dissertatio de Phthriasis. Bonnae, 1820. 4to.
t Systema Antliatorum, p. 240. 2. J Ibid., p. 34] . 4.

560

PHYSIOLOGY.

themselves it is but with the greatest trouble and cleanliness that they
can be removed. All day long they repose tranquilly, and it is only at
night that they attack mankind. Towards morning they retire into
their retreats, and do not, like the flea, accompany man also by day,
secreting themselves between the clothes and the body. They are
sensible of all kinds of odours, for example, citric acid, the sweat of
horses, assafoetida, sulphur, &c. will drive them away for a time.

Besides these constant parasites there are a multitude of other insects
which as blood suckers annoy man by their punctures : such are the
gnats ( Culices ), the genera Ceratopogon and Simulia (to which,
according to all probability, the mosquitos belong, if this name be not
applied without distinction to all kinds of small puncturing Diptera ,
and which thence comprises in different countries very different insects),
the Tabani (especially Chrysops and Hcematopota), and the Stomoxys.
It is usually said of the true gnats that the females only sting, but this
is incorrect 5 it is true that the males are observed less frequently, as
they die immediately after pairing, yet do they sting as well as the
females, as I have myself observed.

Many larvae are also classed among the true parasites of man, as they
have been found in isolated instances in his evacuations. Kirby and
Spence relate several instances in their classical work in which larvae
were either cast up or down. Thus the larvae of Tenebrio molitor, of
Dermestes ( lardarius ? ), and of butterflies ; and even perfect beetles,
for instance, Meloe , have been rejected. According to Azara there is
a brown moth in South America which glues its eggs to the skin of
sleeping persons ; the young larvae bore into the skin, and here live for
a time, until they betray themselves by the pain they occasion, and
when they are pressed out. If this be true it can be referred only to
the genus (Estrus . Indeed it is said that there is a species of this
genus {(Estrus hominis %) the larva of which resides beneath the skin
of man, as is confirmed by Humboldt’s more recent enquiries f. That
maggots of the flies are sometimes evacuated is a frequently occurring
fact known to all physicians, and indeed one instance came under my
own observation during the short period I practised. The maggots
were of the size of the half grown maggots of the flesh fly, and cor-
responded with them ; but they were dead when I saw them, other-

* Gmelin Systema Naturae, vol. i. p. 5. page 2811, No. 10.
+ Essai sur la Geographie des Plantes, p. 1 36.

INSECTS IN RELATION TO MAN.

561

wise I should have endeavoured to rear them. There is no Scolechiasis,
as Kirby and Spence call it, in opposition to Phthriasis, but the in-
stances in which sick people have evacuated the larvae of insects have
been accidentally occasioned.

The advantages which, on the other side, man derives from insects
are also not insignificant. We cannot indeed maintain of any indi-
vidual insect that it forms a very important and necessary food to man,
but there are instances of insects being used as food, and indeed as
delicate dishes. The Cossus of the Greeks and the Romans, which at
the time of the greatest luxury among the latter was introduced at
the tables of the ifich, was the larva of a large beetle that lives in the
stems of trees ; and was, according to Keferstein *, the larva of a
large species of Calandra, a native of Persia and Mesopotamia. In the
Brazils, also, the larva of the large Calandra palmarum is eaten, and
even considered by many as a choice morsel. The grasshoppers are
said to furnish good food to the Bedouins of Egypt. The ancients were
likewise acquainted with this food of the Africans, and they distinguished
a particular tribe by the name of Acridophagi. Even among the
natives of Senegambia and the negroes of the coast of Guinea we find
locusts used as food. The Cicada , which are in many respects closely
allied to the locusts, were eaten by the ancients, especially the fat gravid
females ; the males were less so, as they, from their large air-bladders,
were considered as empty. Amongst the Hymenoptera there are two
families, whose economy has been already described, which yield food,
namely, the ants, which, from their agreeable sour flavour, are eaten by
several Brazilian tribes ; and the bees, whose collected provision con-
sists of honey, of which mention is made as food evpn in the earliest
records, and which is everywhere used as such at the present day.
Manna also, which is the juice of an Arabian plant, the Tamarix
mannifera, dried in the sun, is caused to flow by the puncture of a
small species of Coccus , and is an agreeably flavoured substance, fre-
quently used in the East as food. If the pleasant taste of these sub-
stances readily explains their adoption as articles of food, it is, therefore,
the more incomprehensible how certain tribes, for instance, the Adyr-
machidce, according to Herodotus, the Hottentots and the South
American Charruels, can devour as delicacies their own vermin, a fact
related and confirmed by many travellers.

* Uber den unmittelbaren Nutzen der Insekten. Erfurt, 1829. 4to. P. 8 — 10.

O O

562

PHYSIOLOGY.

As insignificant as all these insects are in point of the supply of food
with which they furnish man, yet many others are extremely important
medicinally. The chief place among these is doubtlessly occupied by
the true Spanish fly ( Lytta vesicatoria), a beetle belonging to the
family of the Vesicifica, the majority of the members of which more
or less possess the same quality. They are applied, when dried, pul -
verised, and spread upon wax or salve, as blisters against rheumatic
affections and the inflammation of the internal organs, and thereby occa-
sion an external attraction. It is for this purpose, not only the most
universal, but also the most powerful and effective means. The ancients
knew this blistering property, but they did not apply our beetle, but
a species of the allied genus Mylabris, to effect this. This beetle they
called KavOap'is, a name applied by Linnaeus to a genus of beetles of a
different family, whence Latreille, supporting himself by the authority
of the ancients, calls Fabricius’s genus Lytta, Cantharis , which, how-
ever, is not to be justified, as properly our genus Mylabris contains the
Cantharis of the ancients. In different countries, however, different
species of the genus Lytta are used for this purpose ; thus L. atomaria,
Fab., in the Brazils, L. gigas , Fab., in Guinea and the East Indies,
L. violacea , Brandt and Ratzeb. *, likewise in the East Indies, L.
vittata , F., in North America, L. marginata, F., also in North Ame-
rica, particularly in Maryland, L. atrata, F., the same, L. cinerea, F.,
in Pennsylvania, L. rufipes , Illiger, in Sumatra and Java. Besides,
the following insects of this family have been used for blistering, Lydus
trimaculus, Fisch. ( Mylabris trim., F.), in the East and in Southern
Europe, Mylabris C ichor ei, F., in China. The species used by the
ancients appears to have been Mylabris Fiieslini, Panz., it is sometimes
found in Germany, and is very abundant in the south of Europe. An-
other genus of this family, namely, Meloe , has been used for a some-
what different purpose. There are twenty-seven species of this genus
distributed over the earth ; all, as far as they are known, secrete a
peculiar yellow fluid, which flows from between the joints of the legs,
which, like all the parts of the Cantharides, has a sharp blistering
effect, and, as this consists of the camphor of Cantharides, it has been
therefore applied as a remedy against the bite of mad dogs and the
consequent hydrophobia, sometimes with success, and at others without
any effect whatsoever, yet modern physicians strongly recommend it.

Arznöithiere, vol, ii. p. 121, &c.

INSECTS IN RELATION TO MAN.

563

No other insects that have been used as medicines, for instance, the
ladybird ( Coccinella), against the toothach, have exhibited such
general utility, nor are there any insects in any of the other orders
which have shown themselves as useful or important as medicines.
Formerly the formic acid was used as a volatile stimulant, whence it
was applied to paralytic affections, but it does not appear to have
exercised much influence upon it. The tannin of galls, produced
by the punctures of many small hymenopterous insects belonging to
the genus Cynips, has been applied as an astringent.

Among those insects which either in themselves or in their produc-
tions present man with materials which his skill has converted into
clothing or articles of luxury, the first place is occupied by a lepi-
dopterous insect, namely, the silk-worm ( Liparis mori). The web in
which this caterpillar encloses itself upon its change into the pupa is
the raw silk, from which, after passing through several preparations
and manipulations, the most beautiful material which human skill ever
produced is woven. Originally a native of China, this material was early
conveyed to the Greeks under Alexander, and subsequently to the
Romans, who also knew the mode whereby it was obtained from a cater-
pillar * ; but this itself remained unknown to them, until, lastly, some
monks, in the reign of Justinian (about 550 after Christ), brought the
first cocoons to Constantinople. From here the cultivation of the silk-
worm spread about 1150 to Sicily and Italy, whence, under Charles the
8th and Henry the 4th, the French transplanted it to France ; since
this period silken raiments have become more general and cheaper.
Even in Germany its cultivation has been attended with success, but
which does not appear to be profitable. Upon the Rhine, in Wurtem-
berg, and in Westphalia, it is still cultivated, where the silk is manu-
factured as a native produce. Thus the worth of silk has infinitely
fallen, and consequently its use has increased in the same ratio. Other
allied caterpillars also produce silk, especially the species of the genus
Atlacus and some South American Papilios, which are no further
known. In Peru, even in the time of Montezuma, materials were
manufactured from the silk, known by the name of misteka, of these
caterpillars.

* See Dr. J. F. Brandt and W. F. Erichson, Monographia generis Meloes. In Nova
Acta Caes. Leop., t- xvi. partii. p. 101, &c.

-j- See Kefcrstein upon the Bonibyx of the ancients, in Germar’s Magazin, vol. iii.
p. 8, &c.

o o 2

564

PHYSIOLOGY.

We may class with the silks, among the useful materials pro-
duced by insects, and which is almost of greater importance, the red
colouring matter that several species of the genus Coccus present us
with. Many of these insects contain within their whole body a very
beautiful red colour, which is extracted by acids ; and these admit
of being used as a colouring matter for all materials. Among the
German species there is one called Coccus Polonicus, which is abun-
dant at the roots of Scleranthus perennis , and which was universally
sought, prior to the introduction of the cochineal, as a red colouring
matter. Since the introduction of the cochineal, however, which is a
species of this genus, known by the name of Coccus cacti, Lin., and
which lives upon the leaves of the Cactus coccinellifer, the Polish cochi-
neal has lost its importance. A third species also, which is native to the
South of Europe, the Coccus Ilicis, which is found upon the branches of
the Quercus coccifera , Lin., and which in the middle ages was especially
used by the Arabians, who applied the still used name of Chermes to it,
has likewise, owing to the more useful Mexican cochineal, been dis-
continued. A fourth species of this genus, the Coccus ßcus, Fab. (C.
lacca , alior.), which dwells in the East Indies upon Ficus Indica, F.
religiosa, and Mimosa cinerea , and which, by puncturing the young
twigs of these plants, occasions the exuding of the clammy resinous
substance which when dry is known by the name of lac, or gum lac,
likewise produces a red colour, which is most concentrated in the eggs,
and the use of which has recently increased so much as to threaten
equalling that of the cochineal.

Lastly, the tannin contained in gall-nuts, and which we have above
mentioned as a medicament, has been used as a colouring matter, as it
forms with iron a black precipitate, that is admirably adapted to this
purpose. The ink also, which to the learned is a very important article,
is made by the assistance of this acid. The species of galls used for
this purpose are of two kinds ; one, the true gall-nut, proceeds from the
Cynips gallce tinctorice, which pierces the leaves of Quercus infectoria,
Oliv., which causes those smooth spherical excrescences upon them ;
the second kind, which are distinguished by being rugose, and of an
angular form, are found on the fruit of Quercus cegylops, and are either
the fruit itself distorted by the puncture, or merely the scaly cup,
which is developed into a gall. The insect which pierces it is, accord-
ing to M. von Burgdorf, Cynips quercus calycis. Both are found in
southern countries, the latter in Greece and in the islands of the
Archipelago, and the former in Asia Minor.

565

ELEVENTH CHAPTER.

THE HABITATS OF INSECTS.

§ 311.

When the question is asked where are insects found, we may
unconditionally reply everywhere except in the sea, for there is no
spot upon the earth accessible to organic beings that is not inhabited
by insects. In this universality of their abode it will appear desirable
to class them under several heads, that we may be thereby enabled to
combine them more closely together ; we may therefore consider this
subject under the differences of elements, the differences of season, and
lastly, the differences of climate, the last of which has usually been
called their geographical distribution, and which, although it has been
already elaborated by several entomologists *, is as yet laid down in
a very meagre outline. The materials we have collected for the com-
pletion of this subject are as yet too imperfect to submit them to the
public, and which we therefore defer to another opportunity, and shall
here consequently only examine them with reference to their abode,
as respects the elements and seasons.

§ 312.

As regards the elements, we have already in several places indicated
that insects are animals of the air, and are referred especially to live
in that element. Yet this means only that the majority of them possess
the power of raising themselves in the air, and there moving at will for
a time, and not that they exclusively dwell in it. The air is absolutely
necessary to every organic being, and in so far every animal is an air
animal ; for although many live in the water, they even here make use
of the air intermixed with it for the preservation of their lives. But
there is yet a certain difference between the different classes of animals
with respect to this necessity, and if insects do not belong to those ani-

* P. A. Latreille, Considerations sur la Geographie des Insectes. Mt'm. du Mus.
1815. — W. S. M‘Lcay, Horae Entomologicac. Lond. 1819 — 21. 8vo. vol. i. p. 1. —
Kirby and Spence, lntrod. to Entom. vol. iv. p. 486, &c.

566

PHYSIOLOGY.

mals which can least bear the withdrawal of air, as some instances cited
above prove their great tenacity of life, they are yet doubtlessly the
animals in which respiration of atmospheric air is most perfectly deve-
loped, and may therefore especially lay claim to the distinction of air
animals. If now, proceeding from another point of view, we should
characterise those groups among insects which of all chiefly reside in
the air, they are doubtlessly the Lepidoptera, to which succeed in the
order of their respective claims the Hymenoptera , Diptera, and Libel-
lulce (compare §§ 125, 126).

There is not a single species among the Lepidoptera which dwells in
the water or exclusively upon the ground, all seek the air, and flutter
about in it, with the exception of a before-named apterous female.
Even their larvae, more than the larvae of any of the other orders, seek
a place in the air, and are best contented in this element. There is but
one caterpillar of a moth (Hotys stratiotalis ) as yet observed to be an
inhabitant of the water, whereas the caterpillars of some of the Noctuce
( Noctua graminis , &c.) are found among stones, or at the roots of
grass, others in the stems of plants (. Noctua typhae , &c.), or in fruits
( Tinea ( Carpocapsa ) pomona, &c.) Similar habitats in concealed
places less accessible to the air are peculiar to several of the inferior
families of the Lepidoptera, whereas the more perfect ones, for instance,
the butterflies and crepuscular moths, all live in the open air upon
plants. The perfect insects of each family, lastly, are constantly in
motion during that portion of the day in which the time of their growth
as larvae falls, and then only occasionally repose : thus the butterflies
are found on wing in the sunshine during day, the crepuscular moths
and Noctuce in the twilight ; the Tinea , again, chiefly by day, but
especially towards the afternoon.

The Hymenoptera are, the next to these, the principal air insects ;
they also, in their perfect state, are never found in the water, and as
rarely as larvae ; yet at this early stage of their existence they consi-
derably diverge from aerial life, and live chiefly in confined close places,
for instance, in holes in the ground, in nests, in the excrescences
of plants, in their stems, and parasitic within other larvae. The
pseudo-caterpillars of the saw-flies only seek the air, and dwell in it
openly upon leaves. The perfect insects possess excessive motion, are
constantly flying about in the air and sucking flowers, and the females
only of some of them as well as the neuter ants are deprived of the
power of flying.

THE HABITATS OF INSECTS.

567

Among the hies, or Diplera, there are several which live as larvae in
the water, as, for instance, the gnats, many Tipulce, and the Stra -
tiomyda , but no perfect insect of this order dwells in this element.
The other larvce, like those of the Hymenoptera, all seek dark remote
places, removed from the air, and come but seldom, and as exceptions,
into day-light.

The same is the case with the Libelluloe, for as much as these in
their perfect state are aerial insects, so strictly as larvae are they confined
to the water.

In the other orders the habitat differs more and more, until among
the beetles it attains its greatest degree of dissimilitude. If we
examine in the first place the Hemiptera , the majority of them are
indeed aerial insects, but also very many are inhabitants of the water.
The family of the lice live parasitic upon mammalia, they therefore live,
although in the air, for the water mammalia have no lice, yet in places
secured from its free access. The Aphides , or plant lice, partly live
in a similar manner, namely, in the excrescences of plants formed by
themselves, but partly also in the open air upon leaves and young twigs.
The Cocci and Chernies have similar places of abode. The true bugs
are chiefly found upon the ground, in the grass, or on trees, or lastly,
upon leaves ; but few are apterous, and these must necessarily crawl
about upon the ground; some genera (Hydrometra, Velia, &c.) run
upon the surface of the water, or dive into it. One genus of this
group, namely, Halohates, Esehsch., courses about upon the surface of
the sea between the tropics, and is the only insect that that has fami-
liarised itself with the sea. The true water bugs ( Hydrocorides ) live
exclusively in the water, exactly as the Cicadaria course about exclu-
sively in the air, upon the leaves of plants and on their twigs.

All the Neuroptera in their perfect state live in the air, where they
fly tolerably constantly and rapidly about, yet their larvae are found
partly in the water, as among the Phryganece and Semblodea , and
partly in sand, as in Myrmecoleon and Ascalaphus , or in the air upon
plants, where they hunt down other insects, as is the case with Rha-
phidia and Hemerobius.

The Orthoptera have received as their chief dwelling-place the
earth itself ; here they are found concealed among grass and plants,
and a few, as Locusta viridissima , upon the elevated parts of plants.
They are therefore especially animals of the earth, which is still more
strongly expressed by the habits of some of the genera, for instance, of

568

physiology.

Acheta and Gryllotalpa, which excavate holes for their dwelling-
places. Some, as the cockroaches {Blattarid), are true nocturnal
animals, which conceal themselves during the day, and only at night
run about upon the ground.

The habitats of beetles are as different as their entire organisation.
Large families, as the Melanosomata and Helopodea, are strictly fixed
to the earth, and scarcely ever quit it. The majority of the Melanoso-
mata have consequently lost the organs of flight with its capability.
Others, as the capricorns, Chrysomelce, ladybirds, and cockchafers, are
found only upon plants, and consequently seek the air, although they,
and chiefly the former, but seldom fly. The Curculios are partly fixed
to the earth, as Brachycerus , Plinthus, Meleus, Cleonis, Thylacites,
Sitona , &c. ; others live upon plants, as Ceutorhynchus , Cionus, Or-
chestes, Phyllobius, Apion, Bhynchites, &c. ; a few, as some species
of Bagous , Hydronomus, Alismatis, Schön., &c. are found also in the
water upon roots, but they do not swim. The true water beetles are
the Dytici, Gyrinus, Hydrophilus , Helophorus, Elmis, and the other
Macrodactyli. The larvae of these also are found only in the water,
whereas the larvae of the preceding families, as far as they are known,
seek remote and concealed places, for instance, the earth and the in-
terior of plants. The larvae of the Chrysomelce and Coccinellce live
chiefly upon plants, partly from which they support themselves, and
partly from the plant lice found upon them. Many insects also seek
dark remote places removed from the open air ; some therefore live in
dung, as the Copropkagi, some in carrion, as the Peltodea, or in both
substances, as the Brachyptera : their larvae also live partly in these
substances or in the earth in their vicinity. Some perfect beetles like-
wise, as the genera Heterocerus and Prognathus, live in the earth,
particularly in the moist sand of the sea coast, but towards evening
they quit these places of abode, and fly about in the dusk. The ma-
jority of the small Carabodea do the same, seeking for prey, although
they but rarely quit the earth during the day. The larger ones are for
ever fixed to the earth, for they have no wings, although the genus
Calosoma forms an exception, the species of which are winged, and
frequently fly. The last family of the beetles, the Cicindelacea, live
chiefly upon sand, but the majority of them can fly as well as they
can run, and immediately exercise this faculty when in danger or if
pursued.

THE HABITATS OF INSECTS.

569

§ 313.

With respect to the several seasons of insects, in cold and temperate
climates, they first present themselves during the warm days of spring,
but, in hot climates, it is during and immediately after the rainy season,
which there supplants winter, that they are seen. We know but little of
the appearance of insects in the highest latitudes. Otto Fabricius men-
tions in his “ Fauna Grcenlandica ” sixty-two species of insects observed
by him in Greenland, of which eleven were beetles, nine Lepidoptera, two
Hymenoptera, nineteen Diptera, seventeen Dictyotopiera (one Libel -
lula, seven Podurce, and nine Mcillophagce ), two Neuroptera, and two
Hemiptera (lice), the most of which he caught in the months of July
and August. But we may readily admit that many escaped him, as may
be presumed from Zetterstedt’s “ Fauna Lapponica,” where very many
more are enumerated. In temperate climates the number of species in-
creases considerably, for in Europe only there are doubtlessly more than
20,000 species, at a moderate calculation. Their time of appearance
varies considerably, yet the time of their greatest activity is the summer :
during the whole of winter there are but few insects in the open air.
The reason of this we may, with Kirby and Spence, consider to be the
deficiency of their aliment, for although many insects do not feed upon
vegetable substances, yet the majority of the flesh feeders obtain their
nutriment from the herbivorous ones, and whose existence is thus there-
fore bound to the vegetable kingdom. It therefore thence happens that
winter, by putting aside the green vesture of the earth, likewise chases
the insects that feed upon it. If we examine this more closely we shall
find that this relation of insects to plants is very absolute, for the
majority of those insects which hybernate in their perfect state are flesh
eaters, which find food even in the young larvae just escaped from
the egg-shell, whilst the latter are feeding sparingly upon the just
developed leaves. If we look to those insects which pass through their
earlier stages during the winter, we may assert generally that all insects
likewise exist during the winter, but in very different states. Some
hybernate as eggs only, others as larvae, others again, and perhaps the
majority, as pupae, and the fewest doubtlessly as perfect insects. From
all these very different states they all assemble as perfect insects in
the summer, and this also is truly the season in which insects are
consequently most active.

As eggs, insects of all orders hybernate, yet these are but few

570

PHYSIOLOGY,

in comparison with their collective numbers. The reason of this is,
that many young larvae, if they were disclosed from the egg early in
the spring, would not find their necessary food ; and other eggs are depo-
sited in substances which are found only in the summer, as leaves of
plants, the larvae of other insects, &c. But we may maintain as a
general fact that those insects especially hybernate as eggs, which deve-
lope in the course of one year two or three generations, as we have
already mentioned of the plant lice ; most of these do not hybernate,
except as eggs. Those also hybernate as eggs whose development
as perfect insects takes place very late in the year, as most of the
Orthoptera , for instance, Acheta , Gryllotalpa, Locusta, Gryllus.
They can therefore pair only very late in the year, so that the
young, should any be disclosed, would no longer find food during the
same year. The females consequently excavate holes in the earth
and bury their eggs therein, when they die, as the males have before
done. The same is the case with the second autumnal generation ; in
this instance also the larvae would no longer find food, the eggs are
therefore disclosed in the spring. Amongst the Lepidoptera , Gastro -
tropacha, Neustria, and Liparis dispar hybernate as eggs. In each
case the mother deposits her eggs on the twigs, and never on the
leaves, of such trees the leaves of which the caterpillars feed on.
Geometra grossulariata, on the contrary, is disclosed the same year,
and hybernates as a larva. It is remarkable that only those Lepidoptera
whose caterpillars live upon perennial plants hybernate as eggs or as
caterpillars, and the rest chiefly as pupae, a phenomenon which even
Roesel observed, and which finds its natural cause in that the leaves of
all annual plants appear later than those of perennial ones. The pupae
consequently are developed later than the eggs, because the imago finds
food only in the flowers, whereas the caterpillars find it in the leaves.
The degree of cold that exposed eggs can endure is not trifling.
Spallanzani placed the eggs of the silkworm in a temperature of
38° Fahr., and yet larvae were disclosed from them, as well as from
others that had been exposed to a temperature of 56° Fahr.

Many insects are found as larvae also during the winter, namely, all
such which pass more than one year in this state, as, for instance,
Melolontha vulgaris , Oryctes nasicornis , Lucanus cervus , the large
capricorns, many Elaters, Buprestes , and a multitude of Lepidoptera ,
namely, Euprepia matronula , Cossus ligniperda , &c. Many of them
are said to form a sort of dwelling, for example, Cossus, in which they

THE HABITATS OF INSECTS.

571

pass the winter in a species of torpidity. The rest creep into slits, holes,
or between fallen leaves, where they also fall into a lethargic state. But
this kind of hybernation is the least usual, as the majority of larvae
live but one year, and most of them, even during the summer, pass into
the perfect state. Those larvae which hybernate can, in their lethargic
sleeping state, bear a high degree of cold. Lister says that he has seen
frozen caterpillars, which, upon falling upon hard substances, rebounded
like stones, and yet, after thawing, return again to life. Although
Reaumur was unsuccessful in this experiment, Kirby and Spence
assure us that the larvae of Tipula oleracea have come to life again
after thawing. Bonnet also has observed the same in the caterpillars
of the common white butterfly.

Those insects which hybernate in the pupa state are chiefly the
Lepidoptera , nine-tenths of which, according to Kirby and Spence, do
so. As their entire pupa state is a species of lethargy, it must be
very easy for them to hybernate in it, and consequently endure severe
cold, yet the majority of pupae are nevertheless protected by particular
coverings and places of repose from this influence of the cold. Many
lie tolerably deeply in the ground, in cavities which have been pre-
viously excavated by the caterpillar. Others which hybernate merely
between fallen leaves, as the pupae of Deilepkila Gain , D. Euphorbia,
D. Elpenor , &c., weave these by means of their web into a covering ;
others, as the caterpillars of the Noctuce and Bombyces, weave a perfect
cocoon, which inside is covered with a glue-like substance. The lethargy
of these pupae continues also frequently towards the commencement of
the summer, for the imago only appears when the plants are in blossom.
The larvae also, which live several years, pass their last winter generally
in the pupa state ; we therefore find the perfect insect, as, for example,
the cockchafer, early in the spring.

Perfect insects, which hybernate as such, prepare themselves early
in the autumn for this purpose, especially in the warm days of October.
They consist chiefly of beetles, but also of individuals of all the
other orders, which, like these beetles, have not yet paired. They then
run in troops in every direction, seeking places where they can pass
the winter. These are the apertures and holes of trees, especially those
between the bark and stem of old ones still existing only as stumps.
Here they may be found during winter in multitudes. We especially
find all such insects there, which, as larva) or as perfect insects, inhabit
wood, as the genera Lyclus, Colydium, Rhyzophagus, with their allies.

572

PHYSIOLOGY.

Also Nitidula, Evgis, Allecula, and the Securipafpa. Also the smaller
Carabodea, as Lebia and Dromius, and many others. Some Hymenoptera
also, as the Ichneumons and Diptera, we likewise find in such situations.
Others, as the Harpali, Amarce, and Feronice, prefer lying beneath
stone, generally in small holes, chiefly with their backs turned down-
wards, clinging to the stones with their legs. Others, again, at the foot
of trees, in woods, amongst the moss, sometimes in holes prepared for
the purpose, like the large Carabi, the Elaters, the Silphce , &c. We
in general find them alone in such situations, but sometimes they lie
in multitudes collected together, as Brachinus crepitans , and other
Carabodea. Between leaves the Curculios delight, and we find the
Staphylini under grass. Some Lepidoptera also hybernate at suitable
places in granaries, &c., as Vanessa Urticce , O., V. Polychloros,
V . Cardui, V. Io, also Colias Rhamni, and many Noctuce. These,
therefore, appear very early in the year, as soon as they are aroused by
the warm sunshine. All, especially those which creep beneath bark,
are said to place themselves on the south side, and never, or very seldom,
on the north. Whilst remaining in these hiding-places, they are
generally, unless excessive cold intervenes, pretty lively, and they are
even lured during warm days to quit their retreats, as for instance, the
Carabi , Aphodii , and Staphylini, which then, even in winter, are seen
swarming upon the snow. At what degree of cold torpidity is produced
cannot be easily determined, and it also differs considerably in different
insects. According to Huber, the ants become torpid at — 2° Reaum.,
and previously lay themselves as closely as possible together : this may
happen also earlier or later. In others, its degree also is very different,
according to the temperature. That such a torpid state is actually
found in insects, we may easily convince ourselves by seeking them in
their hiding places, and bringing them by degrees into a warmer tem-
perature, when we see them gradually arouse themselves and become
active. The flies also, which give us their society even during the
winter in our apartments, are active near the fire-place, whereas at the
windows they appear weak and inert.

Some few insects do not appear to become torpid, but even in winter
present themselves. This is well known of Geometra ( Acidalia ) bru-
mata, which appears towards the end of the autumn, and flies about in
orchards, to which, as larva, it is very injurious, until late in the winter.
Others become torpid on cold days, but present themselves on mild ones,
and again gnaw the buds, as the caterpillar of Noclua fuliginosa. This

THE HABITATS OP INSECTS.

573

is also the case with the Trichocera hiemalis, Meig., for it is not rarely
that we find it upon clear sunny winter days, dancing its choral round
in the air over the snow. Others, again, present themselves only with
and upon the snow, as Boreus hiemalis , Lat., a genus allied to Panorpa,
but wingless, which is not rare in woods upon warm winter days ; as
also the Podurce , which swarm like black dust sometimes upon the sur-
face of the snow; and, lastly, the equally apterous Chionea araneoides,
which belongs to the Diptera, with many jointed antennae, and which
Dalman* has described, and which, according to him, is found in
Sweden upon the snow at a temperature of 2° — 3° (of the scale divided
into a hundred) .

If we now cast a glance upon the time of appearance of tropical
insects, the information we have yet received upon this subject is so
imperfect, that scarcely anything satisfactory can be deduced from it.
According to the letter of Westermann to Wiedemann f, at Kiel, which
is so interesting from the intelligence it gives us of the habits of many
tropical insects, insects are found in Java, Bengal, and at the Cape, only
during the rainy season, during which the whole tropical vegetation is
in its highest luxuriance, and they then swarm upon flowers and leaves,
seeking nutriment. Where they conceal themselves during the hot
season is not yet known with certainty, yet they doubtlessly seek places
of retreat similar to those sought out by our own during winter. Thus
the hot temperature of a tropical summer has the same effect upon
insects as the cold of winter with us, and what lures them from their
hiding places with us, drives them there into their concealed places of
resort. Yet it is the same law which is in force, and by which insects
are especially bound to the luxuriant increase of the vegetable kingdom,
for it is only during the warm rainy season that tropical plants are in
blossom, and they are then visited by insects of all descriptions.

Analecta Entomologica, p. 33.

•f Germar’s Magazin, vol. iv. p. 411, &c.

574

PHYSIOLOGY.

TWELFTH CHAPTER.

INSECTS OF A FORMER WORLD.

§ 314.

Since, in modern times, more attention has been paid to the organic
remains of a former world, communications have occasionally been made
of insects of this description, but this class has not yet received all the
elaboration that has been given to the others. The reason of it may be
that insects are not generally found in those formations where the
remains of the other classes are so abundant, namely, in the calcareous
strata of the tertiary period, but are chiefly imbedded in a vegetable
resin known by the name of amber, and which is cast up by the Baltic,
or found in the more recent strata. This substance is found at places,
which, although not lying beyond the limits of scientific cultivation,
yet where the study of a destroyed organisation is not heeded, either
from their remains not presenting themselves, or in very solitary in-
stances; and amber, which is the sole substance in which the remains of
organised beings have been frequently found there, is generally applied
to mercantile purposes, and it seldom happens to fall into the hands of
learned men or the there very isolated naturalists. But within these
few years the incentive to the investigation of native productions has
very much increased, and attention begins to be paid at home to what the
country’s produce has previously only advanced abroad. We cannot
however deny that the study of destroyed organic beings has been
much stimulated and promoted in and by France, especially by Cuvier’s
immortal works. Hence have originated also the labours upon destroyed
insects which are found in other formations, namely, in calcareous marl,
by Marcel de Serres *, who, in a distinct treatise, has characterised the
insects found in it. Berendt has promised a detailed description of the
insects found in amber, and his prefatory remarks upon the existence

Annales des Sciences Nat., tom. xv. p. 18.

INSECTS OF A FORMER WORLD.

575

and origin of amber are already published *. From these preludatory
labours and our own investigations, which we have been enabled to
make in the academical collection at Greifswald and Berlin, the follow-
ing summary is drawn.

§ 315.

Upon commencing with insects which are found in amber, as the
organic remains belonging to an earlier formation, namely, to brown-coal,
we may assert there is not the least doubt that amber is a vegetable resin,
which must have originated like the present copal, that exudes from
the stem of a North American tree, namely, the Rhus copalina, Lin.
The tree which produced amber was doubtlessly lost with the vegetables
whose remains form the strata of brown-coal, and, therefore, amber is
still found in isolated masses in this formation. It more frequently
occurs, as I have above mentioned, amongst the rejectamenta of the
Baltic, and imbedded in the recent strata of its southern coasts,
especially in moory peaty places, where the ground still continues
covered with woods, namely, on the Prussian coasts in Pomerania,
upon the coasts of the peninsula Dars, which partly forms the frontiers
towards Mecklenburg. I have there myself frequently found it in the
situations above described. The way in which insects have been
enclosed in this amber can be no other than that they stuck to the
resin when this was in a fluid state, and were enveloped in it by what
continued to exude. According to the rapidity with which this took
place, depends the condition of the enclosed insect. Those which were
quickly enveloped are perfectly well preserved with their natural
colours, but those which first died and remained for a time exposed to
the open air, are more or less injured, and are surrounded upon the
surface with a white mouldy covering, and which has occasionally
obscured and disfigured the approximate resin. I have observed this
mould in many insects of the Berlin Museum, which came from
Prussia, and which are enclosed in a dark bubbly amber, whereas I
have never observed it in the bright yellow Pomeranian amber. We
might thence conclude that the latter was originally more fluid and the
former slower in exuding, and thence building a further hypothesis that
the two kinds proceeded from different trees.

With respect to the families, genera, and species of insects which

* Die Insekten in Bernstein von Dr. G. C. Berendt. Danzig. 1830. 4to.

57 6

PHYSIOLOGY.

are thus found in amber, we may repeat what has been observed by
earlier inquirers, that they present a conformity, in the majority of
instances, with existing forms, and even an identity of species can be
shown ; but this yet remains undecided, and, in many instances, is not
the case. Among all the amber insects that I have seen, I have rarely
found a completely new or very dissimilar form, but I have in general
immediately recognised still existing genera. I must also agree with
the earlier observers, that the insects found in amber are not those
which belong to our latitudes, yet there are many forms which perfectly
agree with ours. This may especially be said of the smaller flies and
gnats ; but particularly in the cockroaches, many beetles, and the
majority of the Hymenoptera , the resemblance to exotic forms is still
greater. The number of different species of insects that have been
found in amber is not inconsiderable, and convinces us that the class
of insects in a former world, as even now, must have been the most
numerous in species ; but we find in amber only the members of those
families which are found in woods or trees, and scarcely ever water-
beetles, whence, from the abundance of these, we may draw conclusions
as to the multitudes of all the rest.

§ 316.

After these prefatory remarks, we may proceed to the consideration
of the enclosed insects themselves. I shall, however, only give what I
have myself observed, merely mentioning the orders, families, and
frequently also the genera of insects that I have detected in amber, and
reserve their detailed description for another distinct work. I have
been induced to this by the work announced by Berendt of the amber
insects observed by him, and for the appearance of which I shall wait.

In the order of the Coleoptera I have never detected an individual
belonging to the Cicindelce, and of the Carabodea I have only observed
a small Dromius in the collection at Greifswald, whereas Germar * has
discovered another, which he has described and called Lebina resinata.
I have never yet met with a Staphylinns ; it is not improbable that
they, especially the Aleochara , may be found in amber. Nor have I
observed any carrion-beetles nor any pentamerous beetles with clavate
or capitate antennae. I have detected several Elaters, for example.

Magazin der Entomologie, vol. i. Pt. 1, p. 13.

INSECTS OP A FORMER WORLD.

577

one very similar to the E/ater cylindricus , Gyll., and many smaller
species, but I have not found a single Buprestis, although these might
readily offer. The Deperditores are, however, not rare, namely, forms
resembling Anobium pertinax and An. rufipes, Desmarest found,
also, an Atractocerus in amber. A Cantharis very like C. nigricans,
Fab., I have seen in the Berlin collection. Among the Heteromera
I have hitherto only observed a small Opatrum allied to Op, sa-
bulosum. Germar has described a Mor della (M. inclusa). Of the
Tetramern, I detected in the collection at Greifswald the leg of a
capricorn-beetle, but no other insect of this family except a little
creature very like the Obrium testaceum. The Chrysomelce are more
numerous. I saw a small purple shining Haltica, several Cri'oceris ,
and a few Gallerucce. The Bostrychodice are very numerous, but 1
could not determine one with certainty. In Greifswald I met with a
species of Platypus, and in Berlin with several true Bostrychi and
Apata. The Curculios also are tolerably abundant, particularly species
of the genera Pkyllobius, Polydrusus , Thylacites , &c., and some forms
allied to exotic groups, which I could not more closely determine. I
have never observed any of the smaller Curculios, as Ceutorhynchus,
Cionius, or Apion.

The Hymenoptera are very abundant, but I have never observed a
Tenthredo or a Urocerus, although both families live especially in woods
and feed upon vegetable substances, and the latter, as larvae, bore the
stems of trees. But in the Berlin Museum there are several
Ichneumonodea , whose generic affinities I have not yet been able to
determine satisfactorily. One of them has antennae swollen in the
middle like Bassus ( Euceros ) Crassicornis, Grav. An Evania also,
allied to Evania minuta, Fab., is at Berlin and Greifswald. I have
not yet observed a Cynips in amber, although I have seen a Sphex that
certainly belonged to the genus Pepsis, but which is entirely faded, so
that it is impossible to determine the species. It is of about the size
of Pepsis lutaria, Fab. ( Ammophila , Kirby), but the thorax is more
slender, and the abdomen has not so long a petiole, whence it resembles
the American and particularly the African species. Crabros, Scolias,
Mutillas, and wasps, I have not found, but I saw a small form of bee,
which appears to belong to the South American genus, Trigona, Lat.
The ants are the most numerous in this order, particularly true Formicce
and Myrmicce, which have frequently a close resemblance to our native
ones. The majority are apterous neuters, which have fallen into the

p p

578

PHYSIOLOGY.

fluid resin in their excursions. I have also observed in the Greifswald
collection a peculiar form of ant, which I consider new, as it appears
to be no longer existing, at least I know no allied form among the
still living ones.

Amber Lepidoptera are amongst the greatest rarities. I have never
seen one yet. Berendt mentions a large Sphinx in his collection, and
several caterpillars, which also have never occurred to me.

The Diptera, on the contrary, are extremely numerous, and, indeed,
of all the families. Berendt mentions amber Tahani and Bombylii, none
of which have I seen ; whereas in the Berlin collection there is an
Anthrax of the size of our A. semiatra. Besides, I there saw two of
the genus Leptis, not dissimilar in size and figure to the L. aurata,
several Empes, and several species of the genus Tachydromia. Besides,
there are in both collections innumerable small Muscaria , and, among
the larger ones, species of the genera Musca, Anthomya , Scatophaga ,
&c. I observed a great number of individuals of the family Dolicho-
podea, and, among them, the genera Dolichopus, Medeterus, Porphyrops ,
and Rhctphium. Diptera with multiarticulate antennae are even
more numerous, especially the Bolilophagi. I found species of Bole -
tophila, Mycetophila , Leia, and Sciara, frequently perfect, and with
all their colours preserved. 1 think I have also observed Bibios.
True Tipulce are more rarely seen, but I detected one resembling the
T. pratensis , several Limnobice, some small, like L. pulchella , and
others larger. There is also an abundance of gnats, particularly
species of Psychoda, Lasioptera, Cecidomyn, Ceratopogon, even some
Tanypus or Chironomus , but a true Culex I have never discovered.

Next to these the Neuroptera are probably the most numerous.
Berendt possesses the larva of a Myrmecoleon. I myself have seen
but a small Hemerobius , like H. hirtus or Jiiscatus, a Semblis about
the size of S. margin at a, as well as a larva of this family, which is the
more remarkable, as they all live in water ; and innumerable Phryganece
of various sizes.

Among the Dictyotoptera I observed two individuals of the genus
Ephemera in the Berlin collection, as well as two specimens of
Machilis polypoda. According to Berendt, Libellulce are also found
in amber. The most numerous of this order are the Termites in both
collections. I saw several pieces completely filled with them. The
winged ones as well as unwinged larvae and neuters with large heads
are found in it. Germar’s Hemerobius antiquus is a true Termites, which

INSECTS OF A FORMER WORLD.

579

I know from my own inspection of the identical piece of amber in the
collection at Halle. In the Greifswald collection I observed two distinct
species of Psoci.

In the order of the Orthoptera, the Blattaria are the most numerous.
Berendt assures us that he has distinctly detected some American
forms; those which I saw had a greater resemblance to our own
native Blalta Germanica, which is not rare in woods. To these we
may add some Achetce, particularly small not fully developed indi-
viduals. The Berlin collection possesses a piece of amber with an
insect of this familv, that is distinguished by having short filiform
antennae composed at most of sixteen joints., gradually increasing in
size, and a short straight ovipositor. It is of the size of Forficula
minor, but is still a larva. According to Berendt, there are larger
grasshoppers. I have myself only seen a small locust in the Berlin
collection.

In the last order, the Hemiptera , we frequently observe Cicada pre-
served in amber, for example, in the Berlin collection there are several
specimens of a Flata allied to the F. cunicularia . In Greifswald I
also saw several species of Jassus. I have never discovered bugs, but
Berendt and Marcel de Serres have both observed them. Even a
Nepa the former found enveloped in amber. That species of Chermes,
Aphis and Coccus would necessarily occur in amber, might be absolutely
supposed, yet have I never fallen upon any forms belonging to these
families.

§ 317-

Passing hence to the fossil insects that have been discovered in
recent formations, we will first mention the impressions noticed by
Knorr* in the CEnningen calcareous formations, and which chiefly
represent the larvae of Libellula and other water-insects. Impressions
of cockchafers have also been observed in them. Van der Linden
likewise describes a Libellula found in this formation f. The most
complete list of fossil insects has been given by Marcel de Serres, in
the above treatise. According to him, they are found in calcareous
marl, which separates the several strata of gypsum in the quarries of

* G. W. Knorr. Lapides, Diluvii univers. Testes, &c. Norhnb. 1755 — 1773, folio,
vol. i. p. 151, PI. XXXIII. f. 2-4.

t Notice sur une Empreinte d’Insccte renferm^c dans un Echantillon de Calcairp
schisteux. Brux. 1827. 4to. av. f.

p p 2

580

PHYSIOLOGY.

Aix, in Provence, and, consequently, belong to a still more recent
formation. They are accompanied by impressions of different plants,
but never by fish, the impressions of which are also found in distinct
strata. The majority of the insects enclosed by this marl have pre-
served their horny integument, and mere impressions are more rarely
found ; but their colour appears to be gone, as they are of a uniform
brown or black. They are chiefly such insects which live upon a dry
sandy or clay soil, and which partly still are found in the vicinity of
Aix, as Brackycerus undatus, Forßcula par allda, and Pentatoma
grisea. The list given by the above author includes the following
forms.

1. Coleopter a. A Harpalus of moderate size,* a Dylicus also of
moderate size; a small Staphylinus ; a Melolontha, remarkable from
its deep furrows on the elytra ; a Buprestis of the form of Trachys
nana, Fab.; several Melanosoma, among which one like Asida grisea,
also a Chrysomela like C. cerealis ; two species of Cassida , one like
C ' viridis ; many bark- beetles ; one Apate, allied to A. capucina ; an
Hylurgus, a Scolylus, and a Trogosita like T, cerulea ; lastly, innu-
merable Curculios, two Brachyceri, one like Br. nudatus, Dej., the
other like Br. algirus, Fab.; several species of Cleonis, one like Cleonis
distincta, Larinus, Germar ( Rhinobates , Meig.) ; several Meleus, the
still living form of one species ; then Hyperce, Naupacti, one like
N. lusitanicus , Dej., and one Cionis , like C. Scrophularice.

2. Hymenoptera. Three species of Tenthredos, one smaller than T .
viridis, the second larger, and a third of moderate size ; an Ichneumon ;
an Agathis, Lat. ; two Polistes, one species like P. Gallica, the second
like P. morio, Fab.; several Formicce, some larger, some smaller like
F. subterranea.

3. Lepidoptera. One butterfly of the genus Satyrus, from the
communication of another party ; a Zygcena, a Bombyx, perhaps a
Cossus of moderate size.

4. Diptera. An Empis like E. tesselata, a Nemestrina like N.
reticulata, an Oxycera of the size of Stratiomys chamceleon , and one
allied to Xylopkagus ater ; a Microdon and an Ochthera. Of Diptera
with multiarticulate antennae, there are several Bibios, two Penthetrioe,
some minute Sciarce, and one Platyura like P. cingulata.

5. Neuroptera there are none.

6. Dictyoloptera. Many Libellulce, some as large as JEschna grandis,
and their larvae are tolerably abundant.

INSECTS OF A FORMER WORLD.

581

7* Orthoptera. On e Forßcula, like F. parallela ; several Achetce,
one like A. italica, Fab., one like A. campestris, a third very small, a
small Gryllotalpa , perhaps the larva of our species ; a Xya, 111., allied to
the Xya variegata , 111.; a Gryllus, like Gryllus ccerulescens , F.

8. Hemiptera. Bugs especially of several genera, for instance, two
Pentatomce, one like P. grisea, the second like P. oleracea ; two
species of Coreus , from ten to twelve different species of Lygceus, a
small Syrtis} F., three species of Reduvius, of moderate size, a very
characteristic species of Hydrometra, F., a small Gerris, Lat., a Nepa
smaller than N. cinerea , a Cicada like Cicada plebeja ( Teitigona
plebeja, Fab.).

582

FOURTH SECTION.

TAXONOMY.

FIRST CHAPTER.

GENERAL IDEAS.

§ 318.

Taxonomy, which is the last division of the general portion of
Entomology, has to exhibit the means whereby the large host of insects
may, according to certain principles, be classed in divisions and groups,
and also the connexion of these groups together. The necessity of this
grouping and subdivision is not so evident in any class of animals as
the present, as the number of their different forms is very great, and
doubtlessly greater than those of the entire vegetable kingdom. A
computation of the known species has not been indeed latterly made,
and can scarcely be so, as all the known forms are nowhere yet brought
together, or even described, yet a tolerable result may be deduced by
comparing the number of known species of any country with its
indigenous plants, and then forming a comparative computation with
that of all known plants. There are, for instance, in Germany,
including the Cryptogamea, at most 6000 different plants, but certainly
more than 12,000 insects, so that if this proportion be constant, which
may be admitted, the number of known insects, according to the
60—70,000 known plants, will evidently rise to 120 — 140,000 species.
If, now, in concordance with the estimation of the latest and most
successful botanists, we say that about one-third of the collective species
of plants are known, then the number of insects inhabiting the earth
would amount to from 360 — 420,000 species, or, in round numbers, we
may say 400,000. But this number has neither been collected nor
described. Even were we to calculate all that are preserved in the large

GENERAL IDEAS.

583

museums of Paris, London, Berlin, and Vienna, the number of known
species would scarcely extend to one- fourth of this. MfLeay and
Latreille consider 100,000 to exist already in cabinets, yet I much
doubt whether a positive calculation of them would give so many
species. Count Dejean in Paris, whose collection is known to be the
richest private one, calculates the number of his beetles at 21,000, and
in the Berlin collection, according to a general computation, there are
about 28,000 beetles. The beetles stand in proportion to all the other
insects in the ratio of two to three, consequently the Berlin Museum
should therefore possess about 78,000 species, a number which is not,
however, attained, because, as every one knows by experience, the
beetles are more anxiously sought by travellers than the other insects.
Hence I believe the number of known species in collections may be
considered at 80,000, which is certainly not too few, but many more
would not certainly be found. Of these there may be 36,000 beetles,
12,000 Lepidopteray 12,000 Hymenoptera, 10,000 Diptera, 4,000
Hemiptera , 1,000 Ortkoptera, 1,000 Neuroptera , and 2,000 Dictyo-
toptera , including the parasitic Mallopkaga. Taxonomy instructs us
in the division, determination, and the description of these species, as
well as furnishes us with the history of all preceding arrangements.

§ 319.

Every division and grouping of natural bodies has for object the
easier survey of the whole, and thus to facilitate the knowledge of all by
a course easier than the study of the separate individuals. Proceeding
from a somewhat different point of view, their division has for object to
render the discovery of any individual more easy from certain deter-
minate and essential characters, and this can be attained only by the
arrangement of the characteristic marks found in all natural bodies.
We thus obtain a classification which commences with the most general
characters, whence, proceeding to other more limited characters, the
groups are formed, which must be strictly exclusive, if the utility of
the subdivision is to be preserved. By means of such generally-
opposed groups, the list then gradually descends to the lowest of all,
the species, and with the definition of which its purpose is fulfilled.
We call a division made upon these principles artificial or an artificial
system, yet unjustly so, for a system can never be artificial, but must
be necessary and natural. A second point of view proceeds from the
idea that in nature there is a concatenation of beings in every direction,

584

TAXONOMY.

and it seeks in their arrangement to express this interlinking in their
subdivision, and, thereby to produce the proof of the correctness of the
opinion. It thus creates a system which therefore must be natural,
that is to say, such as appears expressed in nature itself. This
system can, however» only be constructed, when not only all the forms,
but also all the ideas which express themselves in these forms, are
known, and when it is seen that every form has absolutely a thought as
its foundation, and that it is not an accidental but a necessary one.
But the idea to which the study of natural bodies leads is their
gradual development, to exhibit which is the proposition of the
systematist-

Both subdivisions, for the system is also a subdivision, have this
in common, that they form groups, the members of which possess
certain characters, and by collecting these groups together by means of
still more general characters, a survey of the entire contents is effected.
They nevertheless sometimes lead to very different results, by separating
a division that connects the rest, and vice versa. But system has the
advantage of not regarding solitary characters only, but all collectively,
and can therefore only separate and connect where nature itself has
marked a separation and connexion.

§ 320.

The methods whereby both attain the goal are different, for artificial
subdivision proceeds from the characters of the last group, which we
generally call species, and collects similar species under one common
character, and thence forms the genus ; the characters common to
genera give those of the higher groups, the orders and their common
characters combine to form those of the classes. It depends, there-
fore, upon every classifier how far he will proceed in separation
and subdivision. Indeed, much difference of opinion exists upon the
determination of the groups between the species and the order, whence
have arisen the several definitions of sub-genus, genus, and tribe. In
fact, opinions will never harmonise upon the claims of genera, because
no universal principle for the structure of genera in an artificial sub-
division can be given. This principle is in itself exceedingly capricious,
and if one maintains thus far a genus extends, and another thus far,
both are certainly right, if only every group which they distinguish as
genera are distinguished by similar and exclusive characters.

The natural system, the object of which is to discover analogies and

GENERAL IDEAS.

585

affinities, does not proceed from characters, but from the idea expressed
in each group, and forms from these, according to the laws of thought,
a philosophical structure. It is requisite, as well for the discovery of
the conception and its formation into an idea, as for the constructing of
the system, to be thoroughly acquainted with all forms, both in their
external and internal characters, for it is these which express the con-
cealed idea : when these ideas are found, their arrangement offers of
itself, if we but keep in view the object of the natural system, namely,
the discovery of analogies and affinities. This concealed idea is properly
the true character, and which is expressed in a natural group, and
so distinguishes it ; if we have the idea, the character is conveyed
with it. These ideas are expressed in the history of the development,
or in the manner in which the individual has evolved itself from its
origin ; then in the form and composition of the internal organs ; then
in the figure, structure, and number of its external organs ; and, lastly,
in its functions, both external, and more particularly those of the
internal" organs. Where there is a resemblance or similarity in all
these relations, there is found a perfect affinity ; but where only some
resemble and others differ, there it is only partial, and it is the greater
the more and more perfectly the several determinate causes harmonise
together. We hence distinguish several kinds of affinity, namely, the
following * : —

1. Gradational affinity. This is founded upon the resemblance of
the several organs in the grades of development, for example, upon a
conformity in the development of the organs of the mouth, whether
these are mandibulate or haustellate ; upon a conformity in the me-
tamorphoses, &c. Insects which present these resemblances in their
organs, and the development of these organs, are brought together
in the same group.

2. Parallel affinity. This is expressed in the mutual relation of the
developed forms of individual organs to the rest. It may happen that
whilst the remaining organs have acquired a tolerably equal develop-
ment, one passes through several, either higher or lower, forms of
development. Thus are produced :

a. Changes of external form in the same grades of organisation, for
instance, beetles with elongate proboscideal mouths imitate the mouths

* See Schulz natürliches System der Pflanzenreiches. Berlin, 1832. 8vo. p. 132, &c.

586

TAXONOMY.

of haustellate insects, although their oral organs are formed as in all
beetles.

b. Repetition of the same form in different grades, for example, a
resemblance between genera of different orders, namely, Tipula and
Bittacus , Mantis and Mantispa, & c.

c. A change of form in individual organs, with a general resemblance
in the rest, for instance, clavate antennae of Hellwigia among the
Ichneumons , filiform antennse in Anthribus among the Curculios , &c.

3. Typical affinity. — It will be found that in general all forms and
grades of organisation in a natural group stand in a certain degree of
resemblance to each other, which relation is considered as the type or
characteristic expression of the group ; where this resemblance is found
there is typical affinity. This can present itself as

The generic type — if the species of a genus agree in form, sculpture,
and colour.

The family type, — if, for instance, the oral organs, antennse, legs, or
the entire form resemble each other in the genera of a family ; and as

The type of the order — if the grades of metamorphoses or the construc-
tion of the body evince a certain conformity, as is very evidently the
case in the Coleoptera.

These three kinds of affinity separate and connect at the same time
the several groups. Gradational affinity presents the characters of the
classes, orders, and higher groups ; typical affinity distinguishes the
natural limits of the lower groups. Parallel affinity again connects the
several groups together. Thus, upon the similitude and dissimilitude
of all the qualities and characters is the natural system founded.

§ 321.

It may now be asked what course does the natural system follow in
the consecutive arrangement of the groups ? In reply to this, we can
scarcely say more than that it arranges the groups according to their
affinities, and this series regulated by affinities is the course of the
system. Nevertheless we can, proceeding from the essence of the
natural system, characterise its course ä priori. It is also the task of
the natural system to show' the developments which a group has passed
through from its simple beginning to its extreme perfection. These
developments are shown to us by physiology, and therefore every natural
system must proceed upon physiological principles.

GENERAL IDEAS. 587

The physiological principles whence the natural system proceeds
are : —

1. That the entire organisation takes its origin from a most simple
beginning, whence by the development of this into several organs, it
elevates itself to its most perfect form. This development exhibits itself
partly in the internal and partly in the external organs, and almost
throughout presents itself in antitheses, for instance, insects with a
metamorphosis and insects without a metamorphosis ; the former are
again divided into those with a perfect and those with an imperfect
metamorphosis, &c. The more these antitheses are divided the more
do they seek to re-unite, in the first place, to preserve their original
unity, and in the second place to produce a new antithesis, as, for
instance, both groups into insects with haustellate oral organs and with
mandibulate oral organs, each of which again strives to approach the
other. Thus lower groups with individual superior organs stand oppo-
site in equal value to the lower groups of the superior grades.

2. This equivalent value produces the mutual relations of the groups,
which re-produces their more intimate concatenation.

Thus we find insects with an imperfect metamorphosis possessing
mandibulate organs, which, from their second degree of development,
strive to rise above those with a perfect metamorphosis and haustellate
oral organs, as, for instance, the Orthoptera are placed by the majority
of systematists above the Diptera and Lepidoptera, which, however, is
inadmissible, from their imperfect metamorphosis.

3. The external organisation can attain a higher grade, while the
internal remains stationary, and thus mark the prefiguration of a
superior group in one that is inferior. It thence happens that the natural
system does not ascend in a direct line from the most simple to the
most complex group, but sends forth on all sides lateral branches,
which, proceeding from a lower grade, strive to attain the highest.

According to these principles, which we have thus made to harmonise
with the views of modern systematists, was the system sketched that
we formerly published *, and which we shall have an opportunity of
presenting, in the historical survey of systems.

Upon passing from these general observations upon the nature and
difference of both divisions to the groups characterised in both, we
shall find them to consist of the following : —

* De Inscctorum systemate naturali. Halae, 1829. 8vo.

588

TAXONOMY.

§ 322.

I. Idea op Species.

A species is that group of natural bodies which agree together in all
their essential, unchangeable characters. The idea of species com-
prises in it a congruency, that is to say, not a mere conformity, but
also a resemblance of its individuals.

A species is the lowest of all the systematic groups, and consequently
the most fixed and conformable ; no further differences are observable
amongst its individuals, all have consisted from the commencement of
this form, and continue so by the propagation of new and congruent
individuals. Yet differences in less essential characters may occur, for
example, in colour, and even in size, and such forms have been called
varieties. They originate from accidental circumstances, which cannot
be predicted. Others, which have been called sub-species, exhibit a
greater conformity together, but which differ in some characters from
the type of the species, and these differences are continued through all
subsequent generations, which is not the case in mere varieties. But
they yet announce themselves as true individuals of the species by a
conformity in essential unchangeable characters, and therefore cannot,
notwithstanding these differences, be separated from it.

§ 323.

One important character which especially identifies the sub-species
with the species is, that they are fertile together. This is a very
definite character, and which is subjected to no divarication ; for how-
soever much the several sub-species of Coccinella variabilis, 111., differ
from each other, so much so that Fabricius considered them as forming
several species (viz. C. 10 -punctata, C. 13-punctata, C. 10 -pustulata,
&c.), we however find them in reciprocal connexion, and there is con-
sequently no doubt that they are all one species. Truly distinct species
never regularly *, or at least but rarely, intermix in a state of nature,
and certainly not fruitfully, although bastards ( species hybrides), that
is, new intermediate ones originating from the intercourse of two species,
produced in a state of captivity, or in a state of life differing from their
original natural state, is not rare among the superior animals. In
reference to this, we may therefore say that sub-species and varieties

* See above, § 292.

IDEA OF SPECIES.

589

are met with pre-eminently among such insects as are found in the prox-
imity of mankind, and there in great multitudes, as, for example, in
the recently mentioned Coccinella , in the cockchafer ( Melolontha vul-
garis), the garden chafer ( Anisoplia horticola ), &c. It is also possible
that the influence the universal cultivation of the country has had upon
even the nutrimental plants, has extended also to them, and has united
together several originally distinct species, as may with much proba-
bility be asserted of the sub-species of the domestic dog.

§ 324.

Many differences of sub-species and varieties depend also upon the
nature of the country and of the climate. Several of our recently
established species have originated from such circumstances, and must
therefore be re-arranged with their original species, as has also been
occasionally done by several authors. Carabus arvensis , F., for
example, is found not so much in fields as in sub-alpine situations, and
here presents itself in its usual form ; C. pommeranus, Oliv., a native
of the north of Germany, is one of these sub-species, which is distin-
guished by its less brilliant colour and less distinct sculpture ; C.
Harcynice, St., also is a sub-alpine variety of the C. caienulatus , F.,
which is found in the woods of plains ; and there are doubtlessly many
new described species of the Carabodea which stand in the same rela-
tion to old and long- known ones.

We must also enumerate with the sub-species the smaller indivi-
duals of many of the Lamellicorns, which have long been separated as
true species under a distinct name, for example, the smaller variety of
Lucanus cervus, or L. capreolus , of many writers. I think it very
possible that these smaller individuals have originated from a deficiency
of food or of a less nutritive quality in the larva state *, and that in
the larger insects this variety must be greater than in the smaller ones,
as the former require more for their support, and are more exposed to
the effects of temperature than the latter, the duration of whose lives
besides is limited in general to one year, whereas the larger ones pass
several years in the larva state. We find smaller, and indeed some-
times very small, individuals of almost all the larger, and especially of
the very large beetles ; and the Lamellicorns particularly exhibit this
variety, for instance, Oryctes nasicornis, Scarabceus stercorarius ,

This idea I find suggested also in Meckel’s vergleichenden Anatomie, tom. i. p. 335.

590

TAXONOMY.

Typhceus, and many exotic species. A striking instance of the influ-
ence which good or bad nutriment has upon the development of the
larva is exhibited to us in the practice of the bees rearing queens from
the larvae of the neuters.

These facts show that the establishment of a true species is not so
easy an affair, and that it requires very comprehensive tact. Good
specific characters however may be derived from the general form, the
form of individual parts, especially of the head and thorax, the sculp-
ture or markings of the external integument ; after which the size and
the relative proportions of different parts ; and lastly, also even colour.

The specific character, or sum of all the essential characters that
define the species, serves for the distinction of a species.

§ 325.

II. Idea of a Genus.

Above the species stands the group, which has been called the
genus. A genus is composed of several species, which agree in certain
qualities of essential parts or organs ; its idea consequently comprises
that of conformity.

This, in itself correct definition, admits however of a variety of inter-
pretations, according to the object aimed at in the foundation of the
system. Artificial classification divides where it observes divarications
and differences in the organs adopted as the basis of the subdivision ;
whereas the natural system regards the harmony of all the organs, and
only forms divisions where divarications of decided importance are
observed in those organs. An example will speedily illustrate this.
Fabricius, whose classification, founded upon the oral organs, is evi-
dently artificial, divided the Chrysomelina , according to the structure
of the parts of their mouths, into several genera, and referred to these
genera all those leaping beetles which Geoffroy and Illiger united in
the one genus Haltica , according as the parts of the mouth, or even
merely the external form, appeared to agree with the characters of this
or that family ; the most prominent character, that of leaping, he left
quite unnoticed, keeping merely the principles of his system in view.
Latterly, however, and even indeed formerly, as soon as it was wished
to form natural genera, the greatest attention has been paid, and justly,
to this power of leaping, and it has consequently been considered as
the chief characters of these creatures, and indeed they appear to be
particularly distinguished by it.

IDEA OF A GENUS.

591

§ 326.

The method whereby we pass through several qualities and characters
which constitute groups, down to the genus, is analytic. The last
group before the species is generally considered the genus. But it is
possible that one or the other of such determinate genera may be still
further subdivided by divarications in isolated characters : are now such
groups to be raised to positive genera ? In general this must be nega-
tived, for as the higher groups were defined by the simultaneous
differences of all the organs, and the peculiarities deduced from them,
so must the genera of a family, besides a decided difference in the
generic characters, exhibit likewise a general transformation in shape.
If this be not the case the genera will necessarily be of unequal value,
and it will therefore never be possible to settle the contest upon the
generic rights of any determinate group. Every discussion and dis-
pute upon any subject rests upon principles ; if upon these a difference
of opinion prevails all further argument is useless, and no satisfactory
result can ever be obtained until one of the contesting parties can be
convinced of the falseness of their principles.

§ 327.

In the structure of new genera there are two wrong roads to be
avoided ; the one is too circumstantial a dividing, and the other is the
unnatural connexion of absolutely different groups.

The first is most easily followed, when, upon the increase of the
number of the species of a genus, the survey of the whole is rendered
difficult. Hence has proceeded in modern times the host of genera
which are in general deficient in all fixed characters, and are frequently
exceedingly superficial, being constructed merely from the external
form and general impression. A distinction, as, for instance, that
which has been used for the separation of Ophonus and Harpalus,
namely, the deeper punctures of the superficies in the former, whereas
in the latter it is smooth, must indeed be regarded when it is extensive ;
but it never justifies the construction of a genus, and can at most serve
for a subdivision of the species within the limits of the genus. Another
instance is exhibited likewise in the same family, namely, the Cara -
bodea, in the genus Feronia, the former subdivision of which into dis-
tinct genera wras founded chiefly upon the form of the prothorax, and
which modern writers have very justly, from its being untenable, re-

592

TAXONOMY.

united into one genus. If, for example, genera might be formed from
mere outline, we might readily form new genera in the large family of
the Elaterodea, from the figure of the prothorax, which would be
equally inadmissible. There are, in fact, among the Elaters, as well
as among their close allies the Buprestes, several natural genera, but
we much doubt whether the many genera of Elaters recently con-
structed by Eschscholz *, from the form of the tarsal joints, may be
considered as natural.

§ 328.

The second by-way we find to have been pursued chiefly by the
older entomologists ; but it originated in the nature of the thing when
but few species were known, and thence their family characters were
adopted as generic characters. Thus all the Linnaean, and many of
the Fabrician genera have become families, and the divarications
they were either not acquainted with, or did not regard, have never
supplied the characters of genera.

§ 329.

It may be asked how are these by-ways to be avoided ?

It has often been considered that exactitude and acuteness were the
qualities that gave a right to found genera. Indeed, every naturalist
who is deficient in these qualifications will vainly endeavour to
form new genera, and never produce anything useful : but, on the
opposite side, is every considerate and acute observer competent to
found new true genera ? We should even here doubt constant success.
A judicious eye corrected by experience, an equally secure feeling of
the value of the discovered differences, as well as the conviction that
only natural genera may be admitted, are the qualifications that com-
bine to form the happy talent in which we may repose unconditional
confidence in the formation of genera. This talent, which, by the
exercise of years, may be extraordinarily increased, was especially and
distinctly exhibited in Fabricius and Illiger, but in the former it
decreased with increasing age, whence many of the genera he last con-
structed are devoid of naturalness ; whereas Illiger rejoiced in its com-
plete perfection throughout the whole of his indeed short but very active
career. This happy talent, or, as it may be called, judicious tact, is

* See Thorn’s Archiv., vol. ii. part i. p. 31, &c.

IDEA OF A GENUS.

593

never doubtful of the characters requisite to the formation of a genus.
Fabricius could not have made a better choice for the determination of
genera than of characters deduced from the oral organs and the antennae,
as these organs are of the greatest importance to the existence of the
insect, both for procuring its nutriment and in its economy. Their
structure is regulated by the former, and they instruct us upon the
latter. If, indeed, much may be said against this selection, from the
difficulty of their investigation and observation, yet it affords no suffi-
cient ground entirely to reject them. Industry and patience overcome
much, and the excellent labours of many modern entomologists, for
instance, of Savigny, prove that a new era in the history of entomology
may be dated from his comparative representation of the oral organs,
and especially from his inquiries into the mouth of the Lepidoptera *.

When such an important point is discovered the definition of the genus
is no longer difficult ; it is only necessary to inspect, if the other parts
of the body present the same differences as the organs of the mouth ; if
this be the case the genus is natural, if not it is artificial and super-
fluous. This is likewise the case in the introduction of the neuration
of the wing for the determination of genera. In many families the
divarication is in such close connexion with the structure of the entire
body that a mere view of the wing suffices to show us the difference of
genera ; but this is often not the case, and to separate the genus Rham-
phomyia, Meig., from Empis, because it has one nervure less at the
apex of the wing, is very artificial, and cannot consist with the prin-
ciples of a natural system. These differences can only be used to
characterise the divisions within the boundaries of a genus, and thus
to facilitate the discovery of a species among a multitude, as Meigen
himself has done in the genus Limnobia ; but the divarication in the
neuration of the wing cannot be raised to the character of a true genus.
But let all entomologists who occupy themselves with the formation of
new genera remember the dogma of Linnaeus, — “ It is not the cha-
racter which forms the genus, but the genus, constructed by nature,
brings forth the character.”

§ 330.

Little that is universally applicable can be said upon the value of cer-
tain organs for the determination of genera, for even the oral organs are

* See his M£moire6Sur les Animaux sans Vertebres. Paris, 1816. 8vo., with figures,

594

TAXONOMY.

sometimes exactly alike in truly different genera ; but the stability of
genera depends in many instances much more upon the judicious
balancing of all the parts of the body , and their differences, in which
case it is only the above mentioned happy tact that can securely
guide the observer. For, however fixed the number of the joints in
the antennae, for example, may be in certain families, yet instances
occur in which they are subjected to much variety. The genus Cimbex
is a case in point, the antennae of which consists sometimes of six,
sometimes of seven joints, of which sometimes one, or two, or three of
them are swollen into a knob. If we compare with this the number
of the joints in the antennae in the whole family of the saw-flies, we
shall speedily perceive that genera formed merely from the number of
those joints cannot absolutely be considered as natural. This number
is still more variable in the genus Forficula, in which almost every
species has a different number, and which likewise is not even uniform
in the individuals of the same species ; and yet Leach has formed dis-
tinct genera founded on these differences.

§ 331.

The sum of the characters adopted for the definition of the genus forms
the generic character, which is either natural when deduced from all
the organs, or artificial when it merely refers to the characters admitted
as the basis of the classification. This again constitutes the essential
character when it merely cites the distinguishing marks of the genus.
The generic description refers neither to the natural nor to the artificial
generic character, but presents the entire form, even to its most minute
divarications ; it is, as it were, a figure in words, whereas the characters
depict in words particular organs only.

III. Idea op the Superior Groups.

§ 332.

It is from characters of greater generality, especially from resem-
blances in form, or the similar structure of certain parts, as the feet,
wings, &c., which yield no generic characters, that the genera group
themselves into superior divisions. This grouping must follow the
principles adopted in characterising genera, if no violence is to be done
to nature. We must here also strive for an equality of value in the
groups formed.

IDEA OF THE SUPERIOR GROUPS.

595

The division immediately above a genus is usually called a family
It is peculiar to the natural system, and by this only is it called forth
Linnaeus and Fabricius, who formed artificial classifications, had no
families.

The characters which distinguish the families are derived not only
from their resemblances in structure in general, but also frequently
from their economy. Thus the allied families of the Carabodea and
Hydrocantkarides, which both live upon prey, are distinguished, as
well from their dwelling-place, and a very definite and easily recog-
nisable form of the body, and also by a very marked difference in the
structure of their posterior legs, whereas the organs of the mouth and
the antennae agree in the types. Were we to deduce the characters of
families from such relations, it could be defined only as one of resem-
blance ; in the similar structure of certain parts in several genera lie
the characters of a family.

§ 333.

We sometimes also remark within the boundaries of a family, espe-
cially of a very comprehensive one, subdivisions, which bear the same
relation to the families as do the subdivisions of a genus to the latter.
Such groups have been indeed called sub-families. They are as useful
for the easier discovery of the genera, as the former for facilitating the
discovery of the species, and they are therefore more artificial than natural
groups. But it depends much upon their mode of division, for this
does not admit of being said of the sub-families of the large family of
the Ichneumonodea, and as little of many others. For the sake of an
example, we may be allowed to state that those three sub-families differ
in the structure of their palpi. The genuine Ichneumonodea have five-
jointed maxillary palpi, and four-jointed labial palpi ; the Braconodea
five-jointed maxillary and three-jointed labial palpi ; the Bassina six-
jointed maxillary and four-jointed labial palpi. Similar groups, founded
upon analogous relations, are found in the families of the Carabodea,
Lamellicornia , Rhynchophora, Vespacea, Apiaria, Muscaria, &c.

§ 334.

The chief group above the family is the order ; it does not so much
depend upon a similarity of individual parts, as upon the entire body,
for instance, whether the thorax be divided in its three segments, or
whether these are closely jointed together ; upon the form and structure

Q Q 2

596

TAXONOMY.

of the larva ; upon the type upon which the oral organs are formed, whe-
ther mandibulate or haustellate ; or upon the fundamental form in the
structure of the wings. All these relations, indeed, produce an external
resemblance, but these resemblances are the result of physiological
divarications. The orders are properly families of greater compass,
yet with the distinction that the family characters are founded upon
a similarity of form of individual limbs, as the feet, antennae ; whereas
the characters of orders are derived from a similarity of form of the
body.

There are likewise other subdivisions between an order and its
families, as between a family and its genera, which have been called
sub-orders, or tribes. The characters of such groups generally consist
in the different form of a certain organ, but which differences, from
their wider distribution, admit neither of being applied to family divi-
sions nor to generic divisions. Thus the Coleoptera are divided into tribes
from the number of their tarsal joints, the Diptera according to the
number of the joints of the antennae, the Hymenoptera according to the
structure of the sting, &c. Yet such tribes are more artificial than
natural, which admits of being demonstrated in the three examples
cited ; they can merely serve to facilitate finding the families, and are
not to be considered as natural groups.

§ 335.

The classes, lastly, are the highest groups of animals ; which, like
the orders, are founded upon the differences of an otherwise uniform
grade of structure, and consequently repose upon the differences of the
grades of organisation. An equal structure and form of the organic
systems and the thence produced very general conformity of external
figure, a similarity of periods of development, and other similar rela-
tions are the characters which justify the formation of classes. All
insects collectively form one class, in as far as they actually agree with
each other in the above characters.

The objects forming classes consequently neither require to be con-
gruent nor equal, nor even externally to resemble each other, as these
qualities are deduced from a conformity of external figure, but they must
all, physiologically considered, be of equal value ; they must all, to
make use of a mathematical illustration, be pure geometrical inconstant
magnitudes, and not at the same time likewise algebraical constant
magnitudes, both of which are virtually different.

CHIEF ENTOMOLOGICAL CLASSIFICATIONS AND SYSTEMS. 597

§ 336.

Some naturalists admit, and certainly correctly, still further divi-
sions, which comprise several classes, but which have no name. They
also are founded upon similarities in the structure of the organs and of
the organic system. The four above explained (§ 88) organic systems,
stand in three different relations to each other ; namely, in the first
group they retain their vegetable character, with the mere addition of
the animal character of voluntary motion ; in the second and third
groups the animal character predominates ; so that in the second,
motion, and in the third, sensation, are especially developed. We
thus obtain the chief types under which all animal forms may be
arranged.

SECOND CHAPTER.

HISTORY OF THE CHIEF ENTOMOLOGICAL
CLASSIFICATIONS AND SYSTEMS.

§ 337.

The earliest essay to group animals in general, and consequently in-
sects, is that of Aristotle (about 330 B. C.). In his works, one of which
is exclusively devoted to Zoology, he indeed nowhere gives a complete
system of animals ; but from hints here and there expressed, it appears
that he separated the Crustacea as a particular group (M aXaKoarpaKa)
from other insects ("Europa). A further division of insects is deduced
from their wings, and from their presence or absence they fall into
"Europa 7 ttlXcotci and "Europa anrepa ; both again consist of several
groups, which are partly perfectly natural. The divisions of Aristotle
are in general so successfully made, that we are perfectly astonished at
his vast genius, which whithersoever it directed itself, always found the
right, and he maintained in everything he attempted an equal greatness.

The labours of his successors are very different. Pliny’s “ Natural
History ” is merely a systematised Encyclopaedia, in which all those

598

TAXONOMY.

works are abridged that the author had read in the course of a life
devoted to science, and which was sacrificed in the contemplation of a
magnificent natural phenomenon. Much is therefore collected without
any criticism ; what was new was not at all introduced, and the old
frequently distorted by the mode of communication.

^Elian’s fC Natural History of Animals ** properly contains merely
anecdotes and characteristic features of individual animals, and no
zoological description, and may be therefore merely noticed.

§ 338.

Since Aristotle, nothing of any consequence, either in antiquity or
in the middle ages, was done for the natural history of animals ; so
that we leap over a space of more than 1800 years, and with Conrad
Gesner re-commence our historical detail.

He, a poor but industrious Swiss (born in 1516), collected every-
thing that was known relative to the history of animals ; he filled up
many gaps by his personal observations, and thus filled five large folios
with merely the natural history of the vertebrata. Before he reached
insects, death carried him off (1558). His posthumous papers upon
this subject fell into the hands of the well-known Joachim Kamerarius,
of whom they were purchased by an Englishman, Dr. E. Wotton,
who sent them to Thomas Penn, in London, to be published ; he, how-
ever, did not fulfil the commission, but these papers fell, when he died,
into the hands of Thomas Moufet, who incorporated them with his
“Theatro Insectorum,” and they were thus imparted to the world
about a century after their origin (1634).

Gesner is justly considered as the restorer of natural history ; it was
by means of his extraordinary industry that long lost treasures were
again made known to that age, which was thus stimulated to further
researches ; had he not existed the world would doubtlessly have still
much longer slept.

His influence, however, did not so much exhibit itself in the natural
history of insects from the above causes, and it was still several lustres
before they were independently and satisfactorily elaborated.

Ulysses Aldrovandus was the first who took notice of these forgotten
creatures, and described them and their natural history in seven
books. We here find the first division of insects into land and water
dwellers, two chief groups, which were still further divided according
to the structure of their legs and wings.

CHIEF ENTOMOLOGICAL CLASSIFICATIONS AND SYSTEMS. 599

After a commencement was thus made to the study of entomology
several amateurs speedily collected. The imperial court painter, Hoef-
nagel, figured insects very beautifully ; Franciscus Redi observed their
origin and propagation ; M. Malpighi made a masterly dissection of
the silkworm ; and Swammerdamm, lastly, investigated insects in the
several stages of their existence, and formed the first essay towards a
natural system. His arrangement of insects was this : —

I. Insects without a metamorphosis.

They, indeed, change skin, but retain their original form. Spiders,
lice, woodlice, and Myriapodce.

II. Insects with a metamorphosis.

1. The creature moves throughout all the stages of its existence;

in the first it is wingless, in the second (pupa) it obtains
the rudiments of wings, and in the third entire wings.

Here are arranged the Neuroptera, Orthoptera , and Hemiptera,
but he did not separate them into distinct groups.

2. The creature, in its central grade of development, is motionless,

but has limbs.

Here the Hymenoptera, Coleoptera, and as appendix, the Lepi-
doptera.

3. In its central stage of development the creature has neither

motion nor wings, but appears as an ovate pupa.

Here the Diptera.

In the author’s Book of Nature, “ Biblia Naturae,” which was pub-
lished after his death, which took place in 1685, this system was
illustrated with examples, and the anatomy of insects especially is
admirably presented.

The now increasing writers upon entomology offered each his own
arrangement, and according to which their subject was presented, but
system still remained subordinate to observation. Thus Joh. Goedart
wrote upon the metamorphosis. Sybilla Merian observed the deve-
lopment of the Lepidoptera, and, from affection to the science, went
herself to Surinam, to continue there her observations. Ant. von
Leuwenhoek made microscopic experiments ; and Antonio Vallisnieri
pursued the path trodden by his predecessors, of describing the meta-
morphoses of insects : works which are still worthy of regard as well
as of emulation.

600

TAXONOMY.

§ 339.

The first true systematist was an Englishman, John Ray ; the fol-
lowing is the arrangement published by him in his “ Method. Insecto-
rum.” Lond. 1705, 8vo.

I. Ametamorphata (insects without a transformation).

1 . Apoda (annulate worms).

a. Terrestria.

b. Aquatic a.

2. Pedata.

a . Hexapoda.

a. Terrestria (lice).
ß. Aquatica.

b. Octopoda (spiders).

c. Quatuordecempoda (lobsters and crabs).

d . Polypoda.

a. Terrestria (centipedes, woodlice).
ß. Aquatica ( Ampkipoda and Isopoda, Lat.).

II. Metamorphota (insects with transformation).

1. Larvis et pupis agilibus (Orthoptera, Hemiptera) .

2. Pupa immobili.

a. Coleoptera (beetles).

b. Aneloptera.

a. Alis farinaceis ( Lepidoptera ).
ß. Alis membranaceis.

f Diptera, bipennia (flies).

ft Tetraptera, quadripennia ( Hymenoptera ).

III. Metamorphosi simplici e vermiculo in animalculum volatici ,

inter posita aliqua quiete (dragon-flies).

A posthumous manuscript of his, containing a detailed history of
insects, Martin Lister published after Ray’s death (1707), at the
command of the Royal Society of London (Historia Insectorum, ed.
M. Lister. Lond. 1710-11), and at the same time appeared a new
classification, which we will also subjoin. It is the following :

I. Insecta ex ovis sphcericis, quce nullam subeunt met amor phosim.

a. Pedibus senis (lice).

b. Pedibus octonis (spiders).

c. Pedibus plurimis (crabs, wood-lice, centipedes).

d. Pedibus nullis (worms).

CHIEF ENTOMOLOGICAL CLASSIFICATIONS AND SYSTEMS. 601

II. lnsecta ex ovis longiusculis, qua; metamorphosim suheunt.

a. Coleopter a.

b. Anelytra.

a. Pennis quatuor ?iudis.
ß. Pennis quatuor farinaceis.
y. Pennis duabus.

This arrangement is in fact nothing more than a mere modification
of that already given by Ray, and only differs in that its author has
brought Ray’s third chief group under the second, and unites it with
the Anelytris pennis quatuor nudis.

§ 340.

From Ray to Linnaeus, nothing extraordinary took place for the
arrangement of insects. But when this master of natural history
published his System of Nature, in the year 1735, in three folio sheets,
in which he gave a complete survey of all the then known groups of
animal bodies, insects also were placed by him in a new order, which
he skilfully determined according to the form and structure of their
wings. The following is his division.

The fifth class of his animal system, which comprises those with a
simple heart, white blood, and jointed antennae, contains within it all
the insects and Crustacea. Both together, therefore, form a single
chief group (lnsecta), which is thus subdivided :

I. Insects with four wings.

1. The anterior ones horny. 1. Coleopter a.

2. The anterior ones half horny and half membranous. 2. Hemi-

ptera.

3. The anterior and posterior membranous.

a. All covered with scales. 3. Lepidoptera.

b. All naked. The nervures.

a. Reticulated. 4. Neuroptera.
ß. Ramose. 5. Hymenoptera.

II. Insects with two wings. 6. Diptera .

III. Insects without wings. 7- Aptera.

1. With six feet (louse, flea, and some others).

2. With more than six feet.

a. Head connected with the thorax (spiders, crabs, &c.).

b. Head free (centipedes, wood-lice, &c.).

It is not to be denied that by this arrangement many natural, and

602

TAXONOMY.

therefore, very constant groups, were formed, but, s often the case,
when, in the arrangement of natural bodies, only dn,e principle of
division is adopted, others comprise, in every instance, very different
animals. This deficiency must necessarily be recognised upon con-
tinued inspection, and, therefore, an anxiety must exist to remove
it as much as possible. Above all, the order of the Hemiptera is
subject to many objections, for, in the first place, the character
attributed to it is not found in many of its members, for instance,
in many Cicada, the Aphides , the genus Chermes, &c., as they pos-
sess four perfectly membranous wings, and, secondly, there are
insects united in it, which exhibit the greatest differences in their oral
organs.

These circumstances caused the next systematist after Linnaeus,
who was also a Swede, namely, De Geer, to separate the Linnaean
Hemiptera into several equivalent groups, as well as to the adoption of
a new system, which is the following :

I. Insects with wings. Alata.

A. Gymnoptera.

1. Lepidoptera.

2. Elingula (Ephemera, &c.).

3. Neuroptera (Lihellulce and other Linnaean Neuroptera ).

4. Hymenoptera.

5. Siphonaia (Aphides and Cicada ).

B. Vaginata.

6. Hermaptera (bugs and water-bugs).

7- Hemiptera (cockroaches and grasshoppers).

8. Coleoptera (beetles).

C. Dipiera.

9. Halter ata (Linnceus, Diptera).

10. Proboscidea (the genus Coccus ).

II. Insects without wings. Aptera.

D. Saltatoria.

11. Suctoria (the genus Culex).

E. Gressoria.

12. Aucenata (the genera Lepisma , Podura , Termes , Pedi -

cuius, and Ricinus ).

13. Atrachelia (the spiders and crabs).

14. Crustacea (the Isopoda, Ampiphoda, and Myriapoda of

Latreille. See below).

CHIEF ENTOMOLOGICAL CLASSIFICATIONS AND SYSTEMS. 603

This system, which cannot be called a purely artificial one, as it is
founded upon several principles of division, is yet deficient in its object
as a natural one ; the second and third orders are falsely separated,
although a division of the Linnaean Neuroptera was desirable ; the
fifth must be again united with the seventh, and the tenth belongs as
an integral portion to both ; the twelfth and thirteenth, however, are
both an intermixture of the most distinct creatures, and the fourteenth
cannot make claim to be very natural.

§ 341.

Twelve years (1764) after De Geer’s subdivision, a French naturalist
of the name of Geoffroy stepped forth as a systematise where hitherto
Englishmen and Swedes had for half a century alone presented them-
selves. Indeed, the French had not been idle during this time, to prove
which we have merely to refer to the labours of Reaumur ; but they
had not yet presented themselves as systematists, which is the more
remarkable, as their countrymen subsequently have been most active
in this branch of natural inquiry. Geoffroy ’s system, which, exclusive
of other points, is important from the introduction of the joints of the
tarsi as points of division, has fewer groups than any of the earlier
ones, namely, only the following six.

I. Coleoplera. Mandibles and hard anterior wings. They are

divided into

1. Those with hard entire elytra.

2. Those with hard half elytra. And

3. Those with soft membranous elytra (the Hemiptera of

De Geer).

Each of these groups is subdivided from the number of the
joints of the tarsi, in four or five lower groups.

II. Hemiptera. Sucking oral organs and half hard anterior wings.

III. Lepidoptera . Same as Linnaeus.

IV. Tetraptera. Four naked membranous wings.

a. Feet three jointed ( Libellula , Semblis).

b. Feet four jointed ( Rhaphidia ).

c. Feet five jointed ( Ephemera , Phryganea, Hemerobius,

Myrmecoleon , and the Hymenoptera of Linnaeus).

V. Diptera. The same as Linnaeus.

VI. Aplera. The same as Linnaeus.

From whatever point of view we regard this system, it is equally unna

604

TAXONOMY.

tural, and worse than any of his predecessors. In the second group of
beetles we find the genera Staphylinus, Forjiculo, Meloe, and Necydalis ,
De Geer had already shown that the earwig does not belong to the
beetles. But, indeed, if cockroaches, grasshoppers, and locusts are to
be classed among the beetles, as Geoffroy has done, the earwig may
very well be placed there. What a mixture is not the fourth order
even ! It was very necessary that an active mind should occupy itself
to separate all these errors from the truth, and to raise entomology
from its existing state of childhood to its age of manhood.

§ 342.

This genius was found amongst the Germans ; it was John Christian
Fabricius, who was born in 1748 at Tondern, in the Grand Duchy of
Sleswig: he died upon the 3rd of March, 1808, as Professor at Kiel.
It was indeed time that the Germans should exhibit themselves as a
people that loved science and knew how to promote it, for all their
neighbours had preceded them with celebrated examples ; but it soon
displayed itself in a manner superior to any of the rest, as the most
comprehensive, active, profoundest, and most zealous for science.

His division, which was first published in the year 1775, in his
Systema Entomologise, followed quite a new path, the groups of it
being founded upon organs which had never yet been used by authors
as the principles of subdivision. These were the oral organs.
Fabricius defined the orders (which he incorrectly called classes) by
their differences, and in the course of his progressive investigation he
established thirteen equivalent groups. Both his first and last sub-
divisions we will here subjoin.

His first classification was given in 1775, in the Systema Ento-
mologie.

I. Insects with biting oral organs.

1. Four or six palpi at the maxilla and labium.

a. Maxilla free, uncovered. 1. Eleutherata ( Coleopter a of

Linnaeus).

b. Maxilla covered. 2. Ulonata (Hemiptera of De Geer ; a

portion of the Hemiplera of Linnaeus).

c. Maxilla connate with the labium. 3. Synistata(Neuroptera ,

Hymenoptera , and some Aptera \_Monocul. Onisc. Le-

pisma, Podura~\ of Linnaeus).

d. No maxilla. 4. Agonata (lobsters and scorpions).

CHIEF ENTOMOLOGICAL CLASSIFICATIONS AND SYSTEMS. 605

2. Only two palpi, and indeed upon the maxillae. 5. Unogata
( Libellulce , centipedes, and spiders).

II. Insects with suctorial mouths.

a. With a spiral tongue. 6. Glossaia (Linnaeus’s Lepidoptera).

b. With valvular proboscis consisting of setae. 6. Rhyngota

(the remaining Hemiptera of Linnaeus).

c. With fleshy setiferous proboscis. 7- Antliata (Linnaeus’s

Dipier a).

Howsoever meritorious the undertaking of Fabricius was to discover
a new principle of subdivision, whereby all groups of insects could be
determined, yet this first division by no means answers the requi-
sitions that a strict classification is justified in making. It therefore at
first found but little favour, and the difficulty of the investigation also
impeded it, and in many cases indeed doubt was entertained of the
possibility of the process. In fact, this work was but the first
essay of a new method, and, as such, certainly praiseworthy, in as far
as the attention of entomologists was drawn to parts which had not
previously been regarded, and which, however, as was evident from
this representation, were of the greatest importance for the distinction
of groups, and especially of genera. Fabricius has not therefore
acquired an immortal name in science so much by the establishment
ot his system, as exactly like Linnaeus, by the path he pursued. All
that was distorted and false that originated with him, time in the pro-
gress of the science has removed, and his system is put aside ; but he
is the founder of this mode of arrangement, for which he will never be
forgotten, for this he stands forth as a model to succeeding generations.

The changes to which he gradually subjected his system are manifold.
New orders were established, old ones more correctly restricted, and
the whole was raised to a superior scientific completion. Thus almost
in the evening of his days he proposed the following division in the
supplementary volume to the second edition of his System of Insects.

I. Insects with biting mouths.

A. Two pairs of mandibles.

a. The lower ones having palpi.

1. Free without covering. 1. Class. Eleuther at a (beetles).

2. Covered. 2. — Ulonala ( Orthoptera ).

3. Connate with the labium. 3. — & yuistata (Neuroptera).

4. Distended, thin, coriaceous. 4. — Piegata ( Hymenoptera ).

606

TAXONOMY.

5. Horny, strongly toothed, 5. Class, Odonata ( Libellulce ).
labium without palpi,

b. All without palpi. 6. — Mitosata ( Scolopendra ).

B. A pair of maxilla resembling 7- — Unogata (scorpions and

scissors. spiders).

C. More than two pair of maxilla.

1. Within the labium. 6. — Polygonata ( Isopoda ).

2. Outside the lip closing the 9. Kleistagnatha ( short-

mouth. tailed crabs).

3. Outside the lip, but covered 10. — Exochnata (long-tailed

by th q palpi. crabs).

II. Insects with suctorial mouths.

1. In the mouth a spiral tongue. 11. — Glossata (Lepidoptera).

2. In the mouth a horny pro- 12. — Rhyngota ( Hemiptera ).

boscis, surrounded by joint-
ed sheaths.

3. In the mouth a soft unjointed 13. — Antliata (Diptera).

proboscis.

We perceive from this division that Fabricius had no idea of a
natural grouping, but that he separated from solitary characters when
he could. Thus forms the most allied were torn from each other, and
very different genera were forced into the divisions from one-sided
views ; thus for instance, the flea stands among the Rhyngota , with
which it has nothing in common but its suctorial mouth, whereas we
find the lice among the Antliata , although they pass through no meta-
morphosis. The character of the Odonata is erroneous, for the Libel -
lula have one jointed labial palpi, and the character of the Synistata
does not agree with all, but merely with some genera.

§ 343.

Nevertheless, the system of Fabricius had many followers, especially
because by means of it the genera were more correctly determined than
had previously been the case ; yet its being so unnatural and artificial
displeased many, and, therefore, Illiger * proposed uniting both systems,
that of Linnaeus with the latter, a proposition which he himself executed
in the following manner : —

* In the Appendix to his Käfer Preussens, vol. i. Halle, 1798. 8vo.

CHIEF ENTOMOLOGICAL CLASSIFICATIONS AND SYSTEMS. 607

1 . Coleoptera, Lin., without Forficula

2. Hemiptera, Lin.

Eleutherata, Fab.
Ulonuta , F.
Rhyngota, F.
Glossata, F.

(j a. Odonata , F.

\ b. Synistala, F.
Piezata , F.
Antliata, F.
ra. Unogata, F.

b. Agonata, F.

4 c . Mitosata, F.

d Kleistagnatha, F.
v e. Exochnata , F.

According to this grouping, which, indeed, removes several of the
deficiencies of that of Fabricius, the large Helwig-Hoffmannseggian
collection was to be arranged, and thus made the basis of a detailed
elaboration of entomology, but its execution was prevented by political
events.

Clairville * published almost contemporaneously with this essay of
Illiger’s a subdivision of insects, which, although it had no influence
upon the progress of the science, yet merits a short notice. It was
the following :

3. Lepidoptera , Lin.

4. Neuroptera, Lin. (to which Termes,

Lepisma , and Podura are added)

5. Hymenoptera, Lin.

6. Diptera, Lin. (with Pediculus and Acarus)

7* Aptera , Lin. (without the above-named
apterous genera)

I. Insects with wings. Pterophora.

A. With mandibulate oral organs.

1. Anterior wings horny. 1. Ord. Elytroptera (beetles).

2. . . coriaceous. 2. — Deratoptera [Orthoptera).

3. Wings with reticulated 3. — Dictyoptera ( Neuroptera ).

nervures.

4. Wings with ramose 4. — Phleboptera (Hymenoptera).

nervures.

B. With haustellate oral organs.

1. Wings and halteres. 5. — H alter ipter a (Diptera).

2. . . covered with scales. 6. — Lepidoptera.

3. . . variously constructed. 7* — Hemimeroptera(Hemiptera).

II. Insects without wings.

1. With suctorial oral organs. 8. — Rhophotera.

2. With mandibulate oral 9. — Pododunera.

organs.

Entomologie Helvetique. Zur. 1798 — 1806, 2 vol. 8vo.

608

TAXONOMY.

§ 344.

These were the systems of the preceding century. But the whole
science of zoology, and consequently, therefore, entomology, was
involved in a great and advantageous revolution, promoted by the
general impulse towards a natural system, and which was especially
stimulated by anatomical studies. Blumenbach, by the publication of
his comparative anatomy, had conducted naturalists to this we may
almost say new field, and its elaboration was now commenced with zeal.
Hence was developed the zootomical tendency of zoology, and which
possessed in Cuvier its most distinguished and universally revered
representative. It took, lastly, a physiological direction, which did
not, like the former, merely regard form, but inspected the entire
essence of which form is merely the expression. The latter con-
sequently reposes upon the zootomical, and without which it cannot
be brought to bear, but its tendency to secure us from one-sidedness,
to which the latter so easily leads, is its very greatest advantage. It is
also called the philosophical system, and justly, for the path it pursues
is more philosophical, in as far as it seeks to explain the composite
from the simple, and endeavours to refer the former back to this. But
its foundation being physiology, it justly merits its first name. Oken
and his system are the representatives of this method.

§ 345.

The first new division of animals was proposed about this time by
Cuvier (George Leopold Christian Frederick Dagobert, born 1769 at
Miimpelgarde, in Alsatia, died at Paris in 1832;, and actually executed
in his c Traite Elementaire’. Insects are here still treated according to
the system of Linnaeus, but yet the subsequent divisions are indicated
in the grouping of the orders. The first of these divisions, namely,
the separation of insects into two equivalent classes, was executed
some years later in the Tables appended to his Comparative Anatomy,
where he separated those with distinct blood-vessels as Crustacea , but
left all the rest united as Insecta.

In the interim, another French naturalist, who afterwards acquired
the highest fame in entomology, namely, P. A. Latreille (born 1762
at Brives) published a new division of insects *, which differs from

* Precis des Caracteres Cendriques des Insectes. Brives, 1796. 8vo.

CHIEF ENTOMOLOGICAL CLASSIFICATIONS AND SYSTEMS. 609

the Linnaean merely in establishing the Orthoptera as an order, and
the separation of the Aptera into seven equivalent orders. The following
are the seven new orders :

1. Suctoria (the genus Pulex).

2. Thysanura (the genera Lepisma and Podurd).

3. Parasita (the lice, with Ricinus, De Geer).

4. Acephala ( Unogata , F., spiders, scorpions, and Acari).

5. Entomostraca (the genera Cypris, Daphina, &c.).

6. Crustacea ( Kleistagnatha and Exochnala , F.).

7. Myriapoda ( Mitosata , F., the genera Scolopendra, lulus ,

Oniscus, and allies).

The author professes to have sought their natural arrangement, and
to have founded his divisions less upon a single character than the
general expression of the whole ; but the mode in which he has formed
his system scarcely supports his proposition, for many unnatural sepa-
rations still remain. He, however, claims the positive merit of having
introduced the natural families.

The next arrangement published by Latreille we find in his
f Genera Crustaceorum et Insectorum/ Paris, 1806, 4 vols. 8vo. He
here divides, with Cuvier, Linnaeus's Insecta into two equivalent
groups, Crustacea and Insecta, the former of which he characterises
by the possession of a heart and bronchial respiration, and* the latter by
respiring through tracheae. The class of insects which alone here
concerns us is divided in the following manner :

I. Insects without wings. Aptera.

A. With segments bearing seven or more pairs of legs.

a. Head separated from the thorax.

a. a. Four antennae. Last segments 1. Legion. Tetracera.

of the body without legs.

b. b. Two antennae. All the s eg- 2. — Myriapoda.

ments except the last with
legs.

b. Head connected with the thorax. 3. — Accra.

No antennae.

B. With three segments bearing legs. 4. — Apterodicera.

II. Insects with wings. 5. — Pterodicera.

A. With elytra and wings. Elytroptera.

a. With mandibles. Odontata.

R R

010

TAXONOMY.

a . a. Wings folded transversely. 1. Ord. ColeopLera.

b. b. . . . longitudinally, 2. — Orthoptera.

b. With haustellate mouth. Sipho- 3. — Hemiptera.

nostomata.

B. Without elytra, with wings. Gymnoptera.

a. With mandibles. Odontata .

a. a. Nervures reticulated. 4. — Neuroptera.

b. b . . . ramose. 5. — Hymenoptera.

b. With haustellate mouth. Sipkonostoma.

a. a. Four wings covered with scales. 6. — Lepidoptera .

b. b. Two wings and two halteres. 7* — Diptera.

c. c. No wings or halteres. 8. — Suctoria.

We may oppose to this arrangement, which, as it does not regard

the entire being of insects, is still merely artificial, that it is not
sufficiently strict, for the order of the Suctoria is as an apterous group,
not in its right place among the Insecta pterodicera. And also the
groups which are here considered as equivalent to the Tetracera ,
Myriapoda, Apterodicera, and Pterodicera , are by no means of equal
value, but the two first and two last are most closely allied ; the former
are the subordinate members of a higher group, and the latter also
could at most be placed as equivalent to the orders of the Insecta
pterodicera. Latreille published shortly afterwards a new grouping
of insects in his f Considerations Generales/ &c. (Paris, 1810), his
attention having been aroused by Lamarck’s division of invertebrate
animals ; and he here differed from his former work, by subdividing
Linnseus’ insects into three equivalent groups. The first of these, the
Crustacea, remained as before ; the second, the Arachnides , comprised
all the Insecta aptera of the former system ; the third, the Insecta,
included the earlier Insecta pterodicera, containing the same orders rn
the same series, whereas the second had received some alteration by
the separation of the Insecta apterodicera into two orders, the
Thysanura and the Parasila. Later alterations, which Latreille
repeatedly made, convince us that, even this arrangement, which is so
far superior to the former, neither satisfied the author nor the demands
of judicious criticism. In his own discontent with the result, and his
endeavours to correct it where possible, and to take advantage of every-
body’s views, which, indeed, he has nowhere expressed, yet which is
but too apparent from all his subsequent works, he evinces a deficiency

CHIEF ENTOMOLOGICAL CLASSIFICATIONS AND SYSTEMS. 611

of all the principles which should have guided him in his systematic
labours, and he thereby exposes their being untenable. Thus we find
in his next grouping, published in Cuvier’s Regne Animal (Paris,
1817; 4 vol. 8vo.), the Insecta of Linnaeus again divided into three
groups, but these differently limited. The first, the Crustacea, has
received an addition in the order Tetracera , whereas the second,
Arachnides , is made to sacrifice not only this, but also the Myriapoda ,
Thysanura , and Parasita, which are placed in the third group among
the Insecta. This also received a new order in the Strepsistera,
discovered and established by Kirby, so that it now consisted of twelve
orders. His next division (Families Naturelles du Regne Animal,
Paris, 1825, 8vo.) raises the Myriapoda, after Leach, to a distinct
class, and divides the Insecta into eleven orders, which remain as before
established : the Annulata collectively, which form Linnaeus’ Insecta,
are here first called Condylopa. In the new edition of Cuvier’s Regne
Animal (Paris, 1829, 5 vols. 8vo.) the class Myriapoda is again
reduced to an order among the insects, and their number again raised
to twelve orders, whereas in his latest system (Cours d’Entomologie,
Paris, 1832, 8vo.) they are again made into a class and placed between
the Arachnides and insects, the loss of which in the number of the
orders is made up by the establishment of Forficula as a distinct one.
The following is this system, which is the last published by its author ;

I. Apiropoda. Condy lopes with more than six legs.

1 . Class. Crustacea.

2. — Arachnides.

3. — Myriapoda.

II. Hexapoda. Condy lopes with six legs.

4. Class. Insecta .

A. Insects without wings.

a. Without metamorphosis.

* With mandibulate organs. 1. Order. Thysanura.

** With suctorial mouths. 2. — Parasita.

h. With a perfect metamorphosis. 3. — Siphonoptera.

B. Insects with wings.

a. Elytroptera. The anterior wing
covers the posterior like a
sheath.

r r 2

612

TAXONOMY.

* Mandibulate mouth.

Cases horny. Perfect meta- 4. Order. Coleoptera.

— Dermaptera, the
genus Forficula .
Orthoptera.

— Hemiptera.

morphosis.

Cases horny. Imperfect me- 5.
tamorphosis.

Cases coriaceous. Imperfect 6.
metamorphosis.

** Suctorial mouth. 7«

b. Gymnoptera . Wings alike.

* Four wings.

t Mandibulate oral organs, at
least distinct mandibles.

Wings with reticulated ner- 8.
vures.

Wings with ramose ner- 9.
vures.

tf Suctprial mouth, mandibles 10.
abortive.

** Two wings.

t Two distorted moveable pro- 11.
cesses on the prothorax.

t+ Poisers behind the wings. 12.

We have not space here to enter into the merits of this system, and
we can only remark that the author has made divisions upon mere
external characters, and that, therefore, the naturalness of his grouping,
which he chiefly aimed at, was necessarily lost. This may be asserted
also of the families within the orders ; they are also frequently deficient
in a natural connexion and a natural arrangement.

Neuroptera.
Hymenoptera.
Lepidoptera .

Strepsiptera.

Diptera.

§ 346.

Whilst Latreille was elaborating the natural system during a space
of thirty-six years, other countrymen of his were busied with the same
subject. Lamarck is the first among these. He first proposed the
separation of the Arachnides as a class, and he separated the Insecta
of Linnaeus into the three equivalent groups, Crustacea , Arachnides,
Insecta . The Insecta he subdivided into eight orders, as follows :

CHIEF ENTOMOLOGICAL CLASSIFICATIONS AND SYSTEMS. 613

I. Insects with suctorial mouths.

1. Order. Aptera (merely the genus Pulex, Suctoria, Lat.).

2. — Diptera (besides the Diptcra, the order Rhiphiptera,

Lat., also belongs here, but which differs by a man-
dibulate mouth) .

3. — Hemiptera (the same as Latreille).

4. — Lepidoptera (the same as Linnaeus).

II. Insects with mandibulate mouths.

5. — Hymenoptera (like Linnaeus and Latreille).

6. — Neuroptera ( do. do. ).

7- — Orthoptera (like Latreille, but with the addition of the

order Dermaptera).

8. — Coleoptera (like Linnaeus and Latreille).

All other apterous insects Lamarck places among the Aracknides
and Crustacea. Then the Thysanura, ( Lepisma , Podura,) Myria-
poda, ( Scolopendra ,) Julus and the parasites ( Pediculus , Ricinus)
among the Aracknides, with the scorpions, spiders, and Acari ; the
Crustacea are the same in Cuvier and Latreille.

§ 347.

Another French naturalist, Dumeril, to whom we are indebted for a,
in some degree, peculiar division of insects, in so far differs from the
opinion of his compatriots, that he places insects in the series of
animals above the Mollusca ; his arrangement, with this exception,
is but a slight modification of the Linnaean. He forms two classes of
Linnaeus’ insects, namely, Crustacea and Insecta, the former of which
comprises all the crabs, and the latter, on the contrary, all the six-
legged insects, spiders, scorpions, wood-lice, and Myriapoda. They
are thus brought into eight orders

I. Insects with wings.

A. Four wings.
a. Mouth with mandibles.

a. a. Wings unequal, the anterior horny.

* The posterior transversely folded. 1 . Order. Coleoptera.

** The posterior longitudinally

folded.

2. —

Orthoptera .

b. b. Wings equal.

* With reticulated nervures.

3. —

Neuroptera.

** With ramose nervures.

4. —

Hymenoptera.

014

TAXONOMY*

b. Mouth without mandibles.

a . a. Without a bent proboscis.

b. b. A spirally rolled proboscis.
B. Two wings.

II. Insects without wings.
a. Six legs.

a. a. Mouth a proboscis.

5 . Order. Hemiptera.

6. — Lepidoptera*

7- — Diptera.

8. — Aptera.

1. Family. Rhinaptera
(lice and six-legged Acari )«
b. b. Mouth with mandibles, ab- 2. Family. Ornithomyzce
dominal apex without seta? (genus Ricinus, De

and appendages. Geer.

Mouth with various append- 3. Family. Nematurce

( Lepisma , Podura )„
4. Family. Accra.

ages.

b. Eight legs. No antennae.

c. More than eight legs.

a. a. Body with many segments, each

bearing a pair of legs.

b. b. Body with fewer segments,

fourteen pairs of legs.

The author, besides, endeavoured to reunite more naturally, and by
other principles, the families that had been so monstrously subdivided,
and to reduce, especially, the host of genera, which, as his work was to
serve as a general introduction to the natural history of insects*, is very
much to be praised.

5. — Myriapoda.

6. — Polygnatha

( Oniscus & Armadillo).

§ 348.

The whilst these systems were being sketched by the French,
English naturalists likewise occupied themselves with entomology.
Among these there are especially three which well merit mention,
namely, Leach, Kirby, and Macleay. The system of the last is
founded upon philosophical principles, and which we will therefore
examine last. Leach sketched the following system f .

I. Insects without a metamorphosis. Ametabola.

A. Abdominal apex with setae. 1. Order. Thysanura.

B. without setae. 2. — Anoplura

( Parasita , Lat.).

* Considerations Generales sur la Classe des Insectcs. Paris, 1323. 8vo. av. fig.
f Zoological Miscellany, vol. iii. p. 57 — 60.

CHIEF ENTOMOLOGICAL CLASSIFICATIONS AND SYSTEMS. 615

II. Insects witli metamorphosis. Metabola.

A. With mandibles and wing cases.

a. Metamorphosis imperfect (perfect).

Wings folded transversely. 3. Order. Coleoptera.

b. Metamorphosis half perfect.

Wings folded longitudinally and

transversely. 4. — Dermaptera

( Forjicula ).

Wings folded longitudinally.

With a straight suture. 5. — Orthoptera.

Crossed at the apex. 6. — Dictyoptera

( Blattarid ).

B. With setiform mandibles for punc-
turing.

Wings crossing at the apex, 7« — - Hemiptera

(bugs).

Wings straight, contiguous. 8. — Omoptera

{Cicada).

C. With setiform mandibles and with-
out wings. 9. — - Aptera

( Suctoria , Lat.).

D. With indistinct mandibles, connate

at the base.

Wings covered with scales. 10. — LepidopAera.

Wings generally hairy. 11. — Trichopiera

{Phryganea).

E. With mandibulate mouths, but with-

out wing cases.

cim With simple foot claws. 15. — Diptera.

b . With divided foot claws. 16. — Omaloptera

{Diptera pupipara).

The subdivision of insects into many orders, which the English are
especially fond of, certainly merits no recognition ; only where nature
has set true limits let them be divided, and let us not wilfully destroy
the beautiful picture of harmony she everywhere presents us with.
How, for instance, will the author justify the separation of the
Orthoptera into three orders ; and how the separation of the Trichopiera
and Neuroptera by these principles ; and how the division of the

616

TAXONOMY,

Omaloptera from the Diptera ? What business has the genus
Nycteribia, which forms for him a separate order, Notostoma, in this
company, and which should be among the Acari with the Arachnides ?

§ 349.

William Kirby, who, together with William Spence, has earned an
immortal fame in entomology, by their Introduction to this science, has
inserted in their fourth volume the following system.

I. Insects with mandibles. Mandibulata.

1. Order. Coleoptera (like Linnaeus and Latreille. Eleutherata ,

Fab.).

2. — Strepsiptera, Kirb. ( Rhiphiptera , Latr.).

3. — Dermaptera , Leach (Family Forficula , Latr.).

4. — Orthoptera (like Latreille, but without Forficula).

5. — Neuroptera (like Linnaeus and Latreille, but without

the Trichoptera).

6. — Hymenoptera (like Linnaeus and Latreille).

II. Insects with suctorial mouths. Haustellata.

7- Order. Hemiptera (like Linnaeus and Latreille).

8. — Trichoptera (Leach).

9. — Lepidoptera (Linnaeus and Latreille).

10. — Diptera (like Linnaeus and Latreille).

11. — Aphaniptera, Kirby ( Suctoria , Latr.).

12. — Aptera (all apterous insects breathing through

tracheae) .

* Hexapoda ( Ametabola , Leach, Tkysanura and Parasita,
Latr.).

** Octopoda (Arachnides , Tracheales , Latr.).

*** Polypoda ( Myriapoda , Leach, Latr.).

That many of the orders here partly adopted from Leach cannot be
justified upon principle, must be speedily discovered by every one upon
a close inspection. To separate the earwigs from the Orthoptera , on
account of the structure of their wings, is as wrong as it would be to
raise those beetles which have but half elytra into a distinct order.
Both principles of division are merely family characters. The same
may be said of the order Trichoptera, which has been equally
capriciously separated from the Neuroptera. If even the Phryganea
imbibe their food, yet are their oral organs formed upon the type of

CHIEF ENTOMOLOGICAL CLASSIFICATIONS AND SYSTEMS. 617

mandibulate mouths, and by the same right the beetles and Hymen-
optera, which suck the juices of flowers and plants, for example, the
Lucaiii , many Lamellicorns , and the wasps and bees, should be
removed among insects with suctorial organs.

§ 350.

Upon now passing to the physiological or philosophical systems, we
find their originators to have consisted chiefly of Germans. Proceeding
from the view that organic nature is to be considered as one great
whole, which exhibits in its several members progressive grades of
development up to its very fullest perfection and evolution, the
philosophical system endeavours to characterise these grades of de-
velopment as classes, and then further strives to prove their gradual
perfection in the order of each class. After this idea had been started
hypothetically in Sclielling’s school, Oken sought to transfer it to
natural history, and there practically to apply it. He thence obtained
thirteen classes among animals, each of which is represented by a
successively added organ. Insects occupy the ninth of these classes,
and are characterised as lung-animals. The following * is their
division ;

I. Order. Germ flies (Keimfliegen).

Insects with imperfect metamorphosis.

1. Tribe. Bugs ( Hemiptera , Latr.).

2. — * Schricken’ {Orthoptera and Dermaptera, Latr.).

3. — ‘Bolde’ (Neuroptera, Latr.).

II. Order. Sexual flies.

Insects with perfect metamorphosis and equal wings.

4. Tribe. f Mücken’ ( Diptera and Suctoria , Latr.).

5. — ‘ Immen’ ( Hymenoptera , Latr.).

6. — f Falter’ {Lepidoptera, Latr.).

III. Order. Lung-flies. Beetles (Coleoptera, Latr.).

Insects with perfect metamorphosis, elytra, and wings.

7« Tribe. c Kirner’ ( Coleopt . tetramera , Latr.).

8. — f Schruppe’ {Coleopt. heteromer a, Latr ).

9. — ‘Runke’ (Coleopt. pentamer a, Latr.).

We may object to this arrangement, which tolerably distinctly
exhibits the gradual development of the insect world, that the three

Naturgeschichte für Schulen. Leipzig. 1821. 8vo.

618

TAXONOMY.

chief groups of beetles, which are here made equivalent to the other
tribes, are much more closely allied together, and should properly form
but one tribe ; besides that in the tribe Neuroptera there are insects
with perfect and imperfect metamorphoses, which is opposed to the
principles of the system. Many objections might also be made to
the arrangement of the families within each group, but this would lead
us too far.

The systems of other German naturalists, which are founded upon
philosophical principles, merely diverge from that of Linnaeus in the
consecutive arrangement of the orders : we will therefore no longer
dwell upon them, but only cite Goldfuss and Wilbrand as their
projectors.

§ 351.

We now come to the system of MfLeay *. The following are the
principles which guided him in the distribution.

1. All natural groups of the kingdom of nature return within
themselves, and, consequently, present themselves in the form of
circles.

2. Each of these circles contains five other circles, which are con-
nected together in the same way.

3. Where these circles join, there are intermediate groups by means
of which they are still more closely connected.

4. The members of each circle, which are at the points where the
circles meet, exhibit analogies.

According to these principles, organic nature is divided into two
large circles, one of which comprises the vegetables and the other the
animals. Each consists of five circles, which, in the animal kingdom,
are the following : Acrita ( Infusories and Polypes ), which are
bordered on the one side by the Mollusca, and on the other by the
Radiata ( Medusa and Echinodernia) ; next to the Radiata stand
the Annulosa ( Crustacea , insects), and to the Mollusca the Vertebrata,
which pass over to insects by means of the fishes, and to the Mollusca
by the amphibia. The Annulosa, which chiefly concern us here, again
consist of five principal groups, which have the following characters and
boundaries.

* See his Horae Entomologicae. Lond. 1821. 2 vol. 8vo., and Linncan Transactions,
vol. xiv. p. 46, &c.

CHIEF ENTOMOLOGICAL CLASSIFICATIONS AND SYSTEMS. 619

1. Crustacea. (According to Cuvier, Latreille, &c.) they are con-
tiguous to the Radiata, and especially the Echini. Upon one side they
join the

2. Arachnida. (The spider-like annulosa, according to Latreille,
Lamarck, &c.) On the other side the Crustacea border upon the

3. Amelabola. Insects without a metamorphosis, namely, the Myri -
apoda, Thysanura, and Parasita of Latreille.

4. Haustellata. Six-legged insects with wings and suctorial mouths.
They join the Arachnida , metamorphose, and therefore form with the
following group the true insects.

5. Mandibulata. Six-legged insects with wings and mandibulate
mouths. Their place is between the Haustellata and Ametabola ; the
latter form the transition to the fishes.

Here, therefore, only three orders will occupy us, namely, the Ame-
tabola, Mandibulata , and Haustellata.

Hitherto but three groups of the Ametabola have been found, viz.,
the Myriapoda, which join the Crustacea ; the Thysanura and the
Anoplura ( Anopl ., Leach, Parasita , Lat.), ivhich approach the Man-
dibulata.

The division and affinities of the Mandibulata and Haustellata ,
which are called Insecta ptilota, in contradistinction to the Ametabola ,
as apterous insects, is represented in the following table : —

Ptilota.

Mandibulata.

Haustellata.

Larvae with feet, pupae obtectae.

Trichoptera.

( Semblodes , Phryganea , &c.)

Lepidoptera.

Larvae apods, pupae exaratae.

Hymenoptera.

Larvae varying, pupae free and quiet.

Coleopter a.

Aptera.

{Suctoria, Lat.)

Metamorphosis semi-complete, larva resembles the imago.

Orthoptera.

Hemiptera.

( Hemip . Heteroptera, Lat.)
Larvae with six feet, metamorphosis varying.

Neuroptera.

Homoptera.

{Hemip,, Homopt., Latr.)

620

TAXONOMY.

These circles, which the Mandibulata and Haustellata form, arc
contiguous to each other in the Trickoptera and Lepidoptera, espe-
eially the genus Mystacides , Latr., of the former, makes the transition
to the genus Aglossa, Latr., in the latter. M‘Leay considered
the following families as the connecting links between the two
orders of

Mandibulata and Haustellata.

Bomboptera.

( Tenthrenodea, stand between the
Trickoptera and Hymenoptera.

Strepsiptera, Kirb.

(Between Hymenoptera and Cole-
opter a.

Dermaptera, Leach.

(Between Coleopter a and Orthop-
tera.

Dictyoptera, Lea., Kirb.

(Between Orthoptera and Neu-
tera.

Megalopiera.

( Semblodes between Neuroptera
and Trickoptera.

Genus Psyckoda.
(Between Lepidoptera and Dip-
tera.

Homaloptera.

{Diptera pupipara, Lat., between
Diptera and Aptera.
Genus Aphis.

(Between Aptera and Hemiptera.

Family Hydrocorides, Latr.
(Between Hemiptera and Homo -
ptera.

Genus Aleyrodes, Latr.
(Between Homoptera and Lepi-
doptera.

It is not to be denied that in this arrangement there are many
affinities, but just as many appear forced and unnatural. The opinion
that has also been expressed by Goldfuss and other German naturalists
appears indeed true, that animals in general, and consequently insects,
do not ascend in a consecutive series from the most simple to the most
perfect, but the several groups touch each other in different parts,
thereby receiving other forms, and are frequently interlinked by true
groups of transition. If, now, the determinate adoption of five chief
groups appears forced, and without a sufficient reason, if also we cannot
detect in what relation the osculant groups stand in the system of the
author to the chief ones, whether they are equivalent or subordinate,
and if, lastly, the Hemiptera are incorrectly divided into two orders,
and the entire order of the Trickoptera must be considered as artificial,
as the Pliryganece , Semblodes, and Tenthredonodea are united, we
must yet admit that the author has exhibited considerable skill, correct
judgment and knowledge of the whole, and that his system as an essay

CHIEF ENTOMOLOGICAL CLASSIFICATIONS AND SYSTEMS. 621

to arrange the animal world from this point of view, must not be con-
sidered as without its use, or wholly unsuccessful, although his propo-
sitions are not fully solved.

§ 352.

We have still to explain the system which we have ourselves sketched,
and which we communicated partially in the introduction. To do this
we refer to the chapter upon the metamorphoses, where we gave our
arrangement of the entire animal kingdom, and the relation of insects
to other animals. We there discovered that its physiological character
was its organisation as a motive animal, that is, its division into seg-
ments and joints, but which were, however, collected into three chief
divisions. We do not find this division into three parts in any other
annulose animal ; and as we again find a similar separation in the most
perfect of the Vertebrata, we may conclude that insects are the most
perfect of all the Annulosa. To attain this most perfect grade insects
require a gradual development, which displays itself in their transition
through the earlier animal forms and organisations. This we deno-
minate their transformation, or metamorphosis. The more marked
the transformation the more heterogeneous is the individual in the
several stages of its existence ; and as all insects proceed from the
same point, those, necessarily, whose metamorphosis we call complete
must attain a higher grade than the rest, which transform themselves
incompletely. We thus obtain two chief groups among insects, which
we distinguish as Insecta ametabola and Insecta metabola , but in a
different sense to that understood by Leach. Both commence a new
development in the organisation of the mouth, as they at first exhibit
to us abortive setiform oral organs, only adapted to suction, but in the
higher grades these suctorial organs develope themselves into free
mandibles, with a lip covering them. Thus each group has Insecta
haustellata and Insecta mandibulata. Each of these groups may then
be further subdivided according to the form of the larva, the structure
of the wings, and the entire internal organisation and these divisions con-
stitute their orders. We thus obtain an arrangement, the principles
of which are deduced from the idea of the entire insect, and which, as
this idea becomes separated according to its several characters and con-
stituents, it consequently necessarily and spontaneously forms itself by
the philosophical laws of thought. It is the following : —

622

TAXONOMY.

I. Insecta ametabola.

The larva resembles the perfect insect, yet it wants wings if the
perfect insect be winged ; the pupa in this case have their rudi-
ments ; it runs about and eats.

a. With sucking mouths, which consist of four fine setae, lying

in a sheath ; palpi are wanting ; four biliary vessels, and
generally a free prothorax.

1. Order Hemiptera.

b. With mandibulate mouths : mandibles and maxillae distinct,

the latter having palpi, and generally distinct large supe-
rior lip.

a. Four unequal wings; the anterior ones leathery or parch-
menty, the posterior ones folded longitudinally and also
once transversely ; prothorax always free ; many biliary
vessels.

2. Order Orthoptera.

ß. Four, generally equal, more rarely unequal wings, never
folded, or sometimes none at all: in the first case the
nervures are usually reticulated, and generally many biliary
vessels ; in the last case four biliary vessels, attached to
the intestine ; prothorax sometimes free, sometimes not.

3. Order Dictyotoptera.

II. Insecta metabola.

The larva is a worm, consisting of thirteen segments, either with
or without legs ; the pupa is quiet, or if it moves it does
not eat.

a. Four equally large or equally long wings, with reticulated

nervures ; mandibulate mouths ; few, four or eight, biliary
vessels, rarely more ; prothorax always free.

4. Order Neuroptera.

b. Wings always unequal, the posterior ones sometimes want-

ing, rarely all.

a . Mouths adapted to sucking.
a. a. Instead of posterior wings there are pediculated knobs,
yet the wings are sometimes wholly wanting ; four biliary
vessels ; larvae apods ; a soft proboscis in the mouth, with
several setae and a pair of palpi ; prothorax not free.

5. Order Diptera.

CHIEF ENTOMOLOGICAL CLASSIFICATIONS AND SYSTEMS. 623

b. b. Four wings, generally covered with scales ; six biliary
vessels ; larvae with feet and a distinct head ; the maxillae
forming a spiral tongue ; prothorax not free, but small,
and closely connected with the mesothorax.

6. Order Lepidoptera.

ß. Mouths with distinct, biting mandibles.

a. a. Four naked wings traversed by ramose nervures ;
larvae generally without head and feet, but sometimes with
both ; many biliary vessels ; prothorax not free.

7- Order Hymenoptera.

b. b. Anterior wings, horny elytra ; larvae with head, with or
without feet ; four or six biliary vessels ; prothorax always
free.

8. Order Coleoptera .

Our system is not acquainted with an order Aptera, which we have
found in the majority of the others, as in every case it is artificial, and
must embrace insects of the most dissimilar orders. The most distinct
proof in support of this assertion is furnished by the circumstance that
we find in the same family winged and apterous genera, contiguous
together, and, indeed, in many genera which we have before enu-
merated, the males winged, and the females apterous. From the prin-
ciples of the system we might expect a group containing insects with-
out any metamorphoses, but there cannot be such an one, as the idea
of an insect would be thereby annulled. All true insects whose meta-
morphosis has been denied by other entomologists belong to the group
with an imperfect metamorphosis, and were only considered as deficient
in it, because in them the organ is wanting in which we detect the
imperfect metamorphosis. If, for instance, an insect remains apterous
throughout its whole life, it loses the organ by which we distinguish
the imperfect metamorphosis, but in other respects its development is
conformable to those with an imperfect metamorphosis. We have
therefore applied the name given by Leach to those apterous insects, to
all with an imperfect metamorphosis, for in fact there is no difference
in the processes of development in each. This is the guide to the
correct estimation of our system.

A difference of opinion may exist upon the application of the Lin-
naean names to our orders, as many orders contain entire families to
which those names do not apply, for instance, apterous insects. But I
think it better to retain an old characteristic name, than by means of

624

TAXONOMY.

new ones, formed upon new principles, to increase the already innu-
merable host of names. Groups that are so multiform as are the higher
ones of a natural system can scarcely be distinguished by one name,
and composed of many, as would be requisite in the present instance ;
as, for instance, Insecta ametabola haustellata or Insecta, metabola
maiidibulaia elytroptera appear still less appropriate ; we have there-
fore retained Linnaeus, as the most ancient, but have applied them to
differently determined groups.

THIRD CHAPTER.

OF NOMENCLATURE.

§ 353.

System has not only to attend to the division, but also to the naming
of natural bodies ; this is important, as names serve us as the means
of distinguishing groups which differ from the rest by certain cha-
racters and qualities. Thus the names of insects are as important to
the entomologist as the words of his mother tongue to man in general ;
were there no words there could be no communication of ideas, for they
are the means to express and characterise them. Without the groups
being named, naturalists could not communicate together, and without
a distinction of the known and discovered all would speedily return to
its former obscurity : there is, consequently, in natural history a dis-
tinct chapter, which treats of the doctrine of naming, and which is
technically called the nomenclature. Nomenclature propounds the
laws whereby names must be formed, and investigates the correctness
of existing ones, by the principles of grammar and language. Linnaeus
is the originator of this division of natural history ; he was the first to
introduce systematic names into natural history : before him it was
customary to call animals according to their vulgar name, or by that
imposed by the ancients. By the introduction of these scientific, fixed,
and universally valid names Linnseus has doubtlessly acquired his

OP NOMENCLATURE.

625

greatest merit in science, and if everything else should be forgotten that
he has done, this, which is wholly his work, will secure his name from
forgetfulness.

§ 354.

The groups to be distinguished by separate names are those of which
we have treated in the first chapter of this section ; for every species,
genus, and higher group has its distinct name. With respect to the
form of these names, Linnaeus determined that the names of genera,
and of all the higher groups should be substantives, whereas those of
species must be adjectives which should refer to the substantive name
of the genus. This mode of distinction has the advantage of requiring
fewer substantives than if all the species were to be named by them ;
and also the same distinguishing adjective can be applied in many
genera, which would not be the case if substantives were used. It is
indeed also allowed to use substantives as the names of species, but
then they are proper names, and are not to be understood without the
addition of the genus. Thus Linnseus distinguished most of the but-
terflies by giving them mythological or historical names, for example,
Papilio Priamus, P. Hector, P. Hecuba, &c.

§ 355.

The structure of the generic name, as the chief word for the distinc-
tion of the lowest groups, will first occupy us. The most appropriate
name for a genus would certainly be that which at the same time cha-
racterises it. Fabricius, indeed, maintained optima nomina, quce omnino
nil significant, but we do not participate in this opinion ; a name
that expresses a character is in every case better than an absolutely
foreign and unmeaning one. But every one in this may follow his
own opinion, and he who has discovered a genus has the privilege of
naming it, be it by cities (. Edessa ), rivers ( Halys ), or heroes ( Poly-
phemus'), and maidens ( Daphnia , Cypris ). If, however, the name
expresses the character, and is formed for this purpose by composition,
this must follow the laws of grammar and language, and is not allowed
the same caprice as the choice of the name itself ; here choice can make
but the first step, all the rest are subject to immutable laws. By not
following these laws compound words have been recently formed, which
scarcely bear the least trace of what they should properly be, and
words have been made which neither Greeks nor Bomans would admit

s s

626

TAXONOMY.

to be theirs, although they have been published as derived from the
Greek and Latin. Fortunately, entomology is less encumbered with
these monstrosities than other portions of zoology, for instance, orni-
thology, and yet we should have to sweep long before we cleansed away
all the rubbish. We must therefore be satisfied with stating some of
the laws by which such names should be formed.

1. The words intended to compose the name must be of the same
language. There were many delinquencies against this natural law
even formerly, for instance, Monoculus, Insectology , &c. It would
require too many innovations to remove all such hybrid words ; but let
no new ones be thus formed, for it is opposed to the fundamental laws
of language.

2. A Latin word cannot receive a Greek termination, nor can a
Greek word a Latin one, but entire Greek words may be transmuted
into Latin. Grammar teaches the modifications the word undergoes
in this case ; its explanation would here lead us too far. Cicindeletae is
erroneous, for Cicindela is Latin, and eta is doubtlessly from the
Greek termination irrjs ; it should therefore be Cicindelina.

3. New words may be formed either out of two substantives or a
verb and substantive, or an adjective and substantive, or a preposition
and a substantive.

In every case the rule is that the chief idea stands behind, appended
to the root of the first word, and generally with an inserted vowel. In
Greek words this vowel is o, and in Latin words i. If the second sub-
stantive in Greek commence with a vowel, the o is contracted, or cut off,
in Latin the i is omitted. But this rule does not obtain in every case ;
exceptions are sometimes admitted, which analogies determine, for
example, Glossotheca is derived from yXcoao-a and 6t]kt] ; the root, after
rejecting the termination, of the genitive, is yXaxro-, therefore yXc oao-oOrjKrj
in Greek. Fissipes comes from fissus and pes ; Jiss is the root, thence
Jissipes. Linnaeus’s word Myrmeleon is wrong, as it comes from pvppi ^
and \ea)v, it should therefore be called Myrmecoleon , for pvppr/% is the
root, and not pvpprj. Latreille incorrectly writes Melasoma, whereas
it should be Melanosomata, for pe\as has in the genitive peXavos, and
therefore peXav is the root, not pe\a.

In prepositions the connecting vowel remains away if they terminate
in a vowel, for instance. Metathorax from pera and Owpag. Even this
vowel is rejected if the following word commences with a vowel.

If the second word in composition be a verb there is appended to

OF NOMENCLATURE.

627

the root, in Greek words, the terminations os, e, and ov, which are
transformed in Latin into us, a , and urn. Many verbs also in this
composition transmute a vowel of the root, for instance, 4>epo does not
form ({repos, but cfropos , thence Aspidiphorus. In Latin verbs us is
appended similarly, for example, Carnivorus , derived from caro, gen.
carnis, root, earn and vorare, root vor, thence vorus, the i is the in-
serted vowel, whence we have carnivorus.

4. New generic names are formed chiefly from Greek words, partly
because Greek compounds are more harmonious, and partly because the
Greek is richer in words, and more flexible than the Latin.

§ 356.

The laws are the same for the composition of the names of groups.
With respect to the form of the generic name itself, it can only be
altered when urgent circumstances demand it, for the name is sacred,
and no one dare touch it with impunity. Two circumstances only,
namely, false construction and previous application, warrant its altera-
tion. The sex of the generic name is optional, and may be left wholly
to the taste of the originator, but within certain groups, wherein a certain
sex has been introduced for the genera, it is as well to continue it for the
sake of uniformity. The genera Carabus, Anihia, Calosoma , Bembi-
dium stand together in one family, notwithstanding their difference of
sex. But if a new genus be separated from an old one the sex must
be left unaltered, else it may too easily occasion confusion and misun-
derstanding in the specific names.

Generic names consisting of two separate words, as we find them in
the older writers, Fabricius justly rejects, for example, Ray’s Vespa
Ichneumon for Ichneumon, or Petiver’s Musca apiformis for Bom-
bylius, &c. Whereas Fabricius goes too far when he wishes to reject
words composed of two Latin substantives, as Gryllotalpa, Lin.
Generic names that sound badly, or are too long ( nomina sesquipe-
dalia et enuntiatu difficillima) must also be avoided, as well as such
as have objectionable double meanings *.

If a new genus be separated from an old one, the best known and
commonest species must be left with the old name, and a new one must
be invented for the rarer ones : hence Linnaeus’s Scar abceus ster cor arius,

Fabricius, Philosophia Entomologie», p. 115. § 32.
s s 2

628

TAXONOMY.

is more appropriately called in Fabricius Scarabceus, than in Latreille
Geotrupes, for, next to the cockchafer, it is the commonest of all Lin-
naeus’ Scar aber.

§ 357.

Family groups were deficient in the older systems, and therefore also
family names ; but as the families have been chiefly formed from the
external resemblance of their individuals, it appears appropriate to
express this conformity in the name, and they are therefore called
after the best known genus. Thus Jussieu proceeded when he
devised names for his natural families of plants. They took the form
of an adjective, as the substantive planta was tacitly understood ; all
therefore required the feminine gender, for example, Maluacece, Gra-
minece , &c.

Latreille, the first founder of families among insects, selected also
generally the adjective form, but he did not consider that the word
insectum was to be understood, and that, consequently, they should be
neuter. The gender of these names appeared to him indifferent, and
we thence find in the same order every possible form, for example,
Cicindeletce , Carabici, Malacodermi, Pimeliarice, Melosomce , Bru-
cheies, Rhyncostoma, &c. But all adjectives must necessarily, even
when they stand alone, refer to an understood substantive, which in
this case can be no other than insectum or insecta , and therefore all
generic names must, according to the first grammatical rule that the
predicate shall agree with its subject in gender, number, and case, be
in the neuter. Latreille’s family names must therefore be corrected by
this and the previously instituted laws. Let us examine more closely
the way in which he and others have constructed the names of families.

§ 358.

Four different paths have been followed in the structure of family
names.

The first is that pursued by Jussieu in botany, namely, to form an
adjective name from the chief genus of a family for its distinction, and
by means of this name to indicate its resemblance with a known form.
This process appears to be the best, in the first place, because we can
never be at a loss for a family name, and secondly, because these adjec-
tives are easily formed, and merely the knowledge of the derivation of

OF NOMENCLATURE.

629

the generic name, whether it be from the Latin or the Greek, is re-
quired. But then regard must be had to the form of the termination
of the adjective, as this is always determinate for certain purposes.
The termination of adjectives derived from animals is always ecos in
Greek, and in Latin bins; it is, consequently, with these terminations
that generic names must be formed into family names. Thus, for
instance, from Syrphus we must form the family name Syrpkea,
because the « in its transit into Latin becomes long e, as in Pythago-
reus , derived from IlvOayopeios. From the Latin word Cicindela we
should make, according to this rule, Cicindilina , and not with Latreille,
Cicindeletoe. The terminations aceus, a , urn, which Jussieu introduced
into the families of plants, express the resemblance to the object of
the root of the word, and could therefore be perfectly correctly applied
also in Latin generic names, yet the termination inus should be pre-
ferred, as it is the most usual and common to indicate a derivation from
animals, as Asininus, Equinus , Ovinus, &c.

§ 359.

A second adjective termination for family names is that which has
originated from the composition with eiSos, which the Greek termina-
tion oeldrjs or c odjjs gives. It also expresses a resemblance with the idea
of the root, but can only be united with such words as originate from
the Greek. We nevertheless find in Linnaeus errors against this rule,
for example, Curculionides derived from Curculio. Error has fre-
quently happened from appending this termination to the nominative, as
it, which is the case in all compounds, should be added to the root, con-
sequently to the genitive upon the rejection of the genitive termination.
The Romans, as far as I know, have received no Greek word thus
formed into their language, and we can therefore merely decide by
analogy upon the transmutation that must take place upon this transi-
tion. In Greek they are of the common gender, and are declined by
the third contracted declension, consequently, upon their transition
into Latin, they would most appropriately follow the third declension
also, and their inflexions be made analogous to original Greek words. I
have thus treated these names, buthave left the uncontracted Greek form
always in the neuter, for the sake of distinction, as Carabodea instead
of Caraboda. It is still doubtful whether we should use oides or odes ,
as both forms exist in the classics, for instance, in Aristotle Kapaßondrjs

630

TAXONOMY.

and Kapaßcodrjs. Buttman gives the form oides as the most correct,,
because eidos has in the ancient language the digamma ; but I have
chosen the contracted form, as it is shorter, and because it is more
frequent in Aristotle.

§ 360.

Besides these adjective forms substantives have been used to distin-
guish families ; latterly, namely, Greek patronymics have been applied
to the construction of family names, but these also can only be formed
of true Greek words. If in the Latin poets forms such as Romulidce
exist, prose absolutely rejects them, and the language of naturalists is no
poetry, but a scientific and consequently pure prose. If, on the con-
trary, they be applied to Greek names, they must be declined according
to the first declension ; upon transition into Latin all are then true
masculines.

Other substantives originate by the compounding of two words,,
according to the above rules. Names like the following are false,
3Ielosoma, Taxicornes , Myrmeleonides ; they should be Melanosomata ,
Taxocera (for cornu is Latin and ragis Greek), Myrmecoleontoides.

The substantive termination ites, which Latreille so frequently applies
to family names, is Greek, and therefore can be appended only to such
words as are of Greek origin. It is always of the masculine gender,
and distinguishes some relation, and therefore a resemblance with the
object represented by the root. It may therefore be unquestionably
used for the structure of substantive family names ; but names like
Curculionitesy Crabronites , are erroneous, as Curculio and Crabro are
of Latin origin.

§ 361.

The names of the higher groups of the tribes and orders are in
general formed of two words, generally substantives, compounded
according to the above rules. It is seldom requisite to form new names
for such groups, as those existing are sufficient, and, at least in insects,
the orders were determined very naturally even by Linnaeus. Although
our system proceeds from different views to the Linnaean, we have yet
retained the names of his orders, as they are everywhere known, and
everybody already connects an idea with them. The names of classes als
have been already correctly distinguished by early naturalists, and even
by the common man in his mother-tongue, so that we scarcely require

OP NOMENCLATURE,

631

them ; but it is only among the lower animals that new ones are neces-
sary, yet those already existing well enough suffice to distinguish even
them. But if new ones are to be formed they fnust be constructed
by the above rules. It is also endeavoured, even in the higher groups,
to express their character in their names.

§ 362.

Specific names (nomina trivialia ) are formed in three ways: they
are either pure adjectives or substantives, in apposition to the generic
name, or the genitive of the predicate, which expresses a relation to
the thing whence the name is derived.

The adjectives are usually deduced from the most remarkable and
striking quality of the insect, and refer to form, colour, general cloth-
ing, sculpture, size, &c. &c. It is scarcely possible to give general
rules for their imposition, it must be left to the tact of every one who
names species to select appropriate names. This is a subject in which
the naturalist can exhibit much skill, and we cannot in this respect
sufficiently admire the talent of the immortal Linnaeus : Fabricius has
also in general invented good names. Comparative names, however,
are not adapted as specific names, as we do not always know whether
the species which we distinguish as the smallest is actually the
smallest ; but when once applied we must leave them where we find
them, if they do not become incorrect by the discovery of one surpassing
them. Fabricius endeavours also to discountenance specific names
derived from the time of appearance, &c., but in this he probably goes
too far; if the field be too much contracted we shall ultimately find no
adjectives for specific names. Some insects likewise frequent very
determinate places, and why then should they not be named after it ?
It however sometimes happens that animals have names that are not at
all appropriate to them, for instance, the genus Eupkone among the
birds, the species of which, travellers say, do not sing at all.

§ 363.

Specific names formed of substantives refer either to the resemblance
which insects have to the object represented by its name, be this
expressed in form, colour, or any other quality ; thus is Amphicoma
vulpes rough, like a fox, and of the same yellowish colour. Or they
express a significant comparison, and are the sports of the fancy of
the namer, for instance, Cerambyx heros, Gcotrupes Hercules, &c.

T T

632

TAXONOMY.

Thus Linnaeus lias wished to indicate the beauty of the butterflies by
giving them names from the mythology and the mythic history of the
Greeks, and restored the heroes and gods of the infancy of the human
race in them ; we here again find Apollo and the Muses, Jason and his
companions, and the vigorous warriors of the plains of Troy.

The genitive of the predicate is also of a double kind. In the one
case it exhibits the locality of the insect, either in its larva or perfect
state. In this case the substantive is either the name of the plant or
animal upon which the insect lives as a parasite, or parts of them,
when they dwell only on certain parts, for example, Apion ulicis, Ceu -
torhynchus echii, Balaninus nucum , (Estrus ovis, Gastrus equi,
Pediculus capitis , &c. The second kind of genitives of the predicate
consists of the names insects have received in honour of meritorious
entomologists, the person imposing the name wishing thereby to ex-
press his estimation for such individuals, for their scientific exertions.
Thus we have Carabus Linnei, C. Fabricii , C. Germari, C . Schon
herri, &c. But latterly there has been too much liberality in thus
naming after individuals, for mere collectors, known to nobody but the
namer himself, have been thus immortalised. In these instances the
idea spontaneously suggests itself, that the namer has thereby wished
to raise his friend to the rank of those entomologists who have promoted
the science by their study and industry, and consequently thus express
the esteem in which he holds their works. But he who cannot distin-
guish between the merits of a naturalist and a collector had better be
silent, lest, by uttering a word, he should betray himself.

633

DESCRIPTIONS OF PLATES.

Frontispiece. 1, Carabus nitens, F. 2, Euceros crassicornis, Grav. 3,
Hemerobius concinnus , Steph. 4, Polyommatus Adonis , Lat. 5, 4:womoia
Gacdii, Walk. 6, Blatta Germanica, L. 7, Acrida variety Kirb. 8, Corizus
Hyoscyarni , Fall.

[-4// the above insects are British, and all but No. 3 in my own collection. — Tr.]

*** All the figures to which no authority is placed are from the author’s drawings.

Plate I. Figure 1, Hemispherical egg of Gastropacha dumeti (Knoch). Fig. 2,
Conical egg of Pontia Napi (Sepp.) Fig. 3, Cylindrical egg of Gastropacha
everia (Knoch). Fig. 4, Hairy egg of the same, a, spot where the hair is
removed, and the eggs exposed to view. Fig. 5, Tun-shaped egg of Vanessa
Urticae (Sepp.). Fig. 6, Lenticular egg of Noctua psi (Sepp.). Fig. 7, Convex
and ribbed egg of Hipparchia Tithous (Sepp.). Fig. 8, Flat lenticular ribbed
egg of Noctua Orion (Sepp.). Fig. 9, The egg of Phalena prunata , with an
apparent cover (Sepp.). Fig. 10, Cup-shaped egg of Orgyia antiqua (Sepp.).
Fig. 11, Turban-shaped egg of Lyccena Betulae (Sepp.). Fig. 12, Flask-shaped
egg of Culetz pipiens (Reaumur). Fig. 13, Thumbstall-shaped egg of Aryynnis
Lathonia (Sepp.). Fig. 14, Petiolated eggs of Hemerobius perla (Reaumur).

A, Natural size. B, One enlarged. Fig. 15, Contiguous eggs of Gastropacha
Neustria{ib.). Fig. 16, Petiolated egg of Ophion luteus (Kirby and Spence).
Fig. 17, Eared egg of Scatophaga putris (Reaumur). A, From the front.

B, From the side. Fig. 18, Tailed egg of Ranatra linearis (GeofFroy). Fig. 19,
Crowned egg of Nepa cinerea. A, Two eggs as they hang together (Kirby and
Spence). B, One with the distended crown (Rösel). Fig. 20, Cylindrical,
pointed egg of Sialis lutarius (Suckow). Fig. 21, Elliptical egg, with the larva
seen through, of Sphinx Ligustri (Sepp.). Fig. 22, Globose egg, with the
larva shining through, of & Noctua (Sepp.). Fig. 23, Egg shell of the egg of
Gastropacha Pini (Suckow). Fig. 24, Embryo with the membranes of Gastro-
pacha Pini (Suckow). A, Head of the embryo, with the already visible eye
points. B, Its body. C, Space in which the amnion is contained, a a a, The
amnion, b b b, The chorion, c c, Tracheae, which distribule themselves upon

T T 2

634

DESCRIPTIONS OF PLATES.

the superior surface of the amnion, d, Main stem of the trachea, which lies
beneath the germen.

PL IT. Fig. 1, Headless maggot of Musca vornitoria. A, a, The hook-shaped
setae projecting from the mouth. B, The flat tail. a a, The two stigmata.
b b, The coronet of fringe surrounding them, cc, The pedal warts. Fig. 2,
The caterpillar, with anal feet only, of CEcophora Rajella (De Geer). Fig. 3,
Maggot with a head of Vespa vulgaris ( ib .). Fig. 4, Larva of Lixus par ap fac-

tious. a , Head, b, Setiform feet, c, Anal propellers (ib.). Fig. 5, Pseudo-
caterpillar with five pair of ventral feet, and one anal proleg of an Hylotoma
(ib.). Fig. 6, Larva of Cetonia aurata (ib.). Fig. 7, Pseudo- caterpillar of
Cimlex (ib.). Fig. 8, Rat-tailed maggot of Eristalis tenax. a a, Anterior
air tubes, b, Anus, c, External sheath of the tail, d, I nternal tube, e, Seti-
form crown at the apex. /, Mouth with furcate mandibles. Fig. 9, Caterpillar
of Pieris Machaon with the tentaculae of the neck extended. Fig. 10, Caterpillar
of Plasia gamma (Sepp.). Fig. 11, Geometer caterpillar of Phalcena betularia
(De Geer). Fig. 12, Caterpillar without anal proleg of Harpyia vinula (Sepp.).
Fig. 13, Caterpillar’s head with its organs, a, Upper lip. b b , Upper man-
dibles. c c, Lower maxillae. d , Under lip with the spinneret, ff , Antennae.
g g , Eyes. Fig. 14, Under lip of the caterpillar of Cossus ligniperda seen
externally (Lyonet). a, Spinneret, b b , Sheath surrounding the base of the

spinneret, e c, Maxillary palpi, dd , Labium. Fig. 15, Head of the cater-
pillar of Vanessa prorsa. Fig. 16, Head of the caterpillar of Apatura iris.
Fig. 17, Feet of the caterpillar of Cossus ligniperda (Lyonet). a, Part of the
ventral membrane, b , Coxa, c, Trochanter, d , Femur, e, Tibia, f, Tarsus.
g , Claw. Fig. 18, Ventral or proleg of the same caterpillar with a double
coronet of hooklets (ib.). Fig. 19, Pupa of Sphinx Ligustri. a, Head-case.
b, Eye-case, c, Tongue-case, d d , Leg-cases, e, Antenna-case. /, Case of

the prothorax, g, Case of the mesothorax. d,Of the metathorax, i i, Of the
ventral segments, k h, Spiracles. I /, Kirby and Spence’s adminicula. *w, Case
of the superior wings, n, Of the under wings, p , Cremaster. Fig. 20, Pendent
pupa of Hipparchia Egeria (Sepp.). Fig. 21, Enclosed pupa of Musca
vornitoria. Fig. 22, Cremaster of the pupa of Noctua dissimilis (Knoch).
Fig. 23, Cremaster of the pupa of Noctua lucipara (ib.). Fig. 24, Pupa of
neuter bee (Swam.). Fig. 25, a, Cremaster of the pupa of Harpya Fagi
(Knoch). b, Cremaster of the pupa of Euprepia mendica (ib.)- Fig. 26, Bound
pupa of Pontia Cratcegi. Fig. 27, Larva case of Stratiomys chameleon (Swamm.).
a, Head. 6, Coronet of setae around the spiracle at the tail, c c, The pupa
shining through.

PI. III. Fig. 1, Larva of Phryganea , with the case in which it dwells
(De Geer). Fig. 2, Larva of Ephemera, a a, Lateral branchial leaves, b b,
Rudiments of wings (ib.). Fig. 3, Larva of Culex, a, Air tube. 5, Anal

DESCRIPTIONS OF PLATES.

(535

tube (Swaram.). Fig. 4, Pupa of Culex, a a, Air tube (ib.). Fig. 5, Larva
of Chironomus. a a , Air tubes at tail. b, Air tubes at breast (Reaumur).
Fig. 6, Pupa of Chironomus. a a, Branchial fasciculus on the thorax (ib.).
Fig. 7, Larva of Corethra. a, Branchial fasciculus at tail, b , First, and c,
Second pair of bladders, which stand in connexion with the intestine f. d ,
Mandible, e, Antennae. Fig. 8, Pupa of Corethra. a a, Air tubes, bb, Anal
leaves (ib ). Fig. 9, Larva of Sivnulia. a a, Fasciculi on the head, which are
perhaps palpi, b b, Antennae, c, Air tube in the thorax, d d , Indicated spi-
racles. e e , Anal air tubes (Verdet). Fig. 10, Pupa of Simulia. a a, Branchial
fasciculi, b b, Wing sheaths, c, Head, d, Thorax from the back, e, Ab-
domen (ib.). Fig. 11, View from above of the head of Carabus glabratus.
A, Skull. a, vertex. B, Frons. b, Sinciput. c, Clypeus. I, Labrum.
O O, Mandibles. yy, First joints of the antennae, a a, Eyes. Fig. 12,
Under view of the same. D, Gula. d, Swollen margin of the same. G,
Occiput. Q,, Mentum. O O, Mandibles. P P, Maxillae, a a, Eyes. Fig. 13,
Lateral view. S, Facies. E, Cheek. F, Temples, y, Socket of the antenna?.
The other letters as before. Fig. 14, Lateral view of the head of Myopa
testacea. B, Frons. a , Vertex. E, Cheek. F, Temples. G, Occiput. M,
Mouth. c} clypeus ( hypostoma , Meig.). d} proboscis. e, Whisker. y.
Antennae. Fig. 15, Labium of Vespa vulgaris, a a, Glandular points of the
four-lobed tongue, b , Chin, c c, Palpi (Treviranus). Fig. 16, Maxilla of
Cychrus roslratus, from above. l,Cardo. 2, Stipes. 3, Squama. 4,Mando.
5, Palpus maxillae internus, or galea, a, Basal joint, b, Apical joint. A, palpus
maxillaris. e, The groove. Fig. 17, The same from beneath. Fig. 18,
Maxilla of Spondyla buprestoides, with the same lettering. Fig. 19, Maxilla
of Melolontha vulgaris, with the same lettering.

PI. IV. Fig. 1, Anterior view of the head of Myopa testacea. a a, Eyes.
y y, Antennae, c c , Hypostoma. d, Proboscis. Fig. 2, Maxilla of Copris
lunaris, with the lettering as in fig. 16 of preceding plate. Fig. 3, Labium of
Cychrus roslratus. A, Mentum. B, Ligula. C C, Palpi. Fig. 4, The same
from within. A, Mentum. B, The bilobed tongue. Fig. 5, Lateral view of
the labium of Locusta viridissima. a, Superior lobe of the mentum, forming
the true mentum. b, Basal joint of the left palpus, c. Basal portion of the
mentum. d, The loose tongue. Fig. 6, Head of Ateuchus sacer. a a. The
eyes(Sturm). Fig. 7, Head of Truxalis nasutus. a, Root of antenna, b. Eye.
c, Labrum. d d, Maxillary palpi, e e, Labial palpi. /, Labium. Fig. 8,
Mandible of Hydrophilus piceus. a, Incisor teeth, b, Molar process, c, Low er
joint ball, d, Superior bent joint ball, e, Situation of the third internal
process, where the flexor muscle is inserted. Fig. 9, Maxilla of Lucanus cervus.
1, Cardo. 2, Stipes. 3, Squama. 4, Mando. 5, Penicillate lobe. A,
Palpus (Sturm). Fig. 10, Maxilla of Cicindela campestris. As far as 4 the
same as above, the latter internally beset with teeth, and with a superior move-

636

DESCRIPTIONS OF PLATES.

able tooth, c. 5, Internal maxillary palpus, a, Basal joint, b, Apical joint.
A, External maxillary palpi. Fig. 11, Labium of Libellula. a, The true
labium, b b , The lateral lobes, which appear to be modified labial palpi, 2 2.
These would then be the second joints of the labial palpus. Fig. 12, Maxilla
of Sphex ( Ammophila ) arenaria. 1, Cardo. 2, Stipes. 3, Squama. 4,
Mando, here forming the membranous sheath of the tongue and labium.

a, Filiform palpus. Fig. 13, Maxilla of Barynotus obscurus. a} Conical
palpus. 6, The maxilla, with four teeth on its inner edge (Germar). Fig. 14,
Maxillary palpus of Melandrya. Fig. 15, Labial palpus of Oxyporus. a, The
groove which exhibits after the death of the insect the palpal surface. Fig. 16,
Maxillary palpus of Lymexylon navale. Fig. 17, Maxillary palpus of Atracto -
eerus necydaloides (Kirby and Spence). Fig. 18, Maxillary palpus of Bern-
bidion (Sturm). Fig. 19, Ditto of Trechus (ib.). Fig. 20, Ditto of Trox,
sabulosus. Fig. 21, Maxilla of Hydrophilus piceus. 1, Cardo. 2, Stipes.
3, Squama. 4, Mando. 5, External lobes, consisting of a, the basal joint,
and b, the hooked, hairy, apical joint. A, Palpus, Fig. 22, Maxillary palpus
of Gryllotalpa vulgaris, a , The swollen palpal surface. Fig. 23, Terminal
joint of the same palpus with the dried up surface, a. Fig. 24, Labial palpus
of Noctua libatrix (Sa vigny). Fig. 25, Ditto of Lithosia pulchella (ib).
Fig. 26, Maxilla of Banchus falcator. The figures the same as in fig. 21.

PI. V. Fig. 1, Proboscis of a Musca. A, The fleshy lip. a , The peduncle.
ß , A portion beyond the knee, y, The knob. B, The seta within the chan-
nelled excavation of the lip. C C, The one-jointed palpus. Fig. 2, Sette which
lie in the fleshy lip of Tabanus. a, Labrum. b b, Mandibles, cc, Maxillae, d.
Tongue. C C, Two-jointed maxillary palpi. Fig. 3, Proboscis of Tabanus seen
from above ; the letters as before. Fig. 4, The same from beneath, d d, The halves
of the knobs of the labium. C C, Palpi of the maxillae. Fig. 5, Labrum from
beneath (Savigny). Fig. 6, Mandible (ib.). Fig. 7, Maxilla (ib.). c , Maxilla.
C, Two-jointed palpus. Fig. 8, Head of Cimex rufipes seen from beneath.
A A, Eyes. B B, First joints of antennae, a, Labrum. b b , Four-jointed
sheath of the proboscis produced by the growing together of the labial palpi.
Fig. 9, Clypeus of the same, with the rostral seta extended. «, Labrum.
c, Mandible still united, d d, Maxillae (Savigny). Fig. 10, Head of Cimex
rufipes , in which the upper integument is removed. A A, The eyes.
c c, The mandibles, with the muscle which affixes each to the occiput.
d d, Maxillae attached by muscles to the tongue, e , Tongue. Fig. 11, Head
of Nepa cinerea seen from above. A A, Eyes, a, Labrum. b b , Sheath of
the proboscis or labium. Fig. 12, The three-jointed sheath of the proboscis
seen from beneath. Fig. 13, Proboscis of Nepa cinerea separated (Savigny).

b , Proboscideal sheath, c c, Mandibles, d d , Maxillae, e, Tongue, at the
base of which is the entrance to the oesophagus. Fig. 14, Labrum of Nepa
cinerea seen from beneath (Savigny). g, Clypeus from within, h, Reflexed

DESCRIPTIONS OF PLATES.

637

margin of the labium. J\ Internal passage for the reception of the maxillary
setse. Fig. 15, Head and oral organs of Noctua libatrix (Savigny). AA, Eyes.

a, Labrum. b 6, Mandibles, c, The maxillae partially united and forming
the proboscis, d d , Maxillary palpi, e e, Articulating cavities for the labial
palpi in the reflexed labium. Fig. 16, Labrum of the same moth separate ( ib .).
Fig. 17, Both of the mandibles of the same moth (ib.). Fig. 18, Labium
of the same moth (ib.). c, Labium, d d , Labial palpi divested of their hair
and scales.

PI. VI. Fig. 1, Maxilla of the same moth (ib.). a, The filiform portion.

b , The palpus. 1, The cardo. 2, The stipes. 3, The squama. 4, The
mando. Fig. 2, Section of the proboscis (ib.). a a, Ridges which close the
central canal of the proboscis above, o, The central canal, p p , The canals
in each half of the proboscis. Fig. 3, Head of Galleria cereana (ib.). A, Eye.
B, Antenna, d. Labial palpus, e, Projecting proboscis. Fig. 4, Parts of
the mouth of the same moth. /, The proboscis, consisting of two halves.
g g, Palpi of the proboscis, d d , Labial palpi, e, The labium. Fig. 5, Head
of a neuter Apis mellifica seen from beneath, a , Mentum. A, Fulcrum.
b , Tongue (a pierced sucking tube), g g , Paraglossae. c c, Four-jointed labial
palpi attached to the tongue close to the fulcrum, d d, Pergamentaceous
maxillae, h h , One-jointed maxillary palpi, f f, Mandibles, n n , Horny
ridges in the articulating membrane of the parts of the mouth, m. Occipital
aperture. Fig. 6, Mouth of the same insect similarly marked, e, The valve of
the oesophagus, the second tongue according to Treviranus. 1, 2, 3, 4, 5, The
several horny bones which lie in the articulating membrane. Fig. 7, Lower
portion of the proboscis (tongue). 6, With the paraglossae a a, (Brandt).
Fig. 8, Anterior view of the head of Apis mellifica. A A, Eyes. B, Stemmata.
C C, Antennae. D, Clypeus. E, Labrum. f f, Mandibles, d d, Maxillae,
c c, Labial palpi, b, Proboscis or tongue. Fig. 9, Head of Phryganea grandis
seen in front. A A, Eyes, a a, Mandibles. b> Labrum. c c, Maxillae.
d d, Maxillary palpi, e e , Labial palpi, f, Spoon-shaped Labium. Fig. 10,
Labium seen from above, c c, Maxillae. e e, Maxillary palpi, d, The
channel of the under lip which leads to the orifice, g, of the oesophagus.
Fig. 30, Labium from beneath, ff, Labial palpi, ee, Basal joints of the
maxillary palpi, g , Fulcrum.

PI. VII. Fig. 1, Setiform antenna of Locusta. Fig. 2, Ditto ditto of Cicada.
Fig. 3, Bodkin-shaped ditto of Leptis. Fig. 4, Filiform ditto of Carabus.
Fig. 5, Moniliform ditto of Tenebrio. Fig. 6, Sword-shaped ditto of Truxalis.
Fig. 7, Sickle-shaped ditto (Kirby and Spence). Fig. 8, Dentate ditto of Stc-
nochorus. Fig. 9, Serrate ditto of Elaier. Fig. 10, Imbricate ditto of Prionus
coriarius, male. Fig. 11, Pectinated ditto of Ctenocerus. Fig. 12, Doubly-
peclinated ditto of Clenophora (Meigen). Fig. 13, Curled antenna (Kirby

638

DESCRIPTIONS OP PLATES.

and Spence). Fig. 14, Fan-shaped ditto of Psygmatocerus (Perty). Fig. 15*
Ramose ditto of Cladius difformis. Fig. 16, Furcate ditto of Schizocerus .
Fig. 17, Geniculated ditto of Apis mellifica. a , Scapus. b, Flagellum.
Fig. 18, Clavate ditto of Silpha. Fig. 19, Capitate ditto of Necrophorus .
Fig. 20, Ditto of Hydrophilus. Fig. 21, Lamellate ditto of Melolontha
fullo, male.

PI. VII T. Fig. 1, Tunicate antenna of Lethrus. Fig. 2, Inflated antenna of
Paussus (Sturm). Fig. 3, Fissate antenna of Lucanus. Fig. 4, Uncinate ditto
of Odynerus , male. Fig. 5, Nodose antenna of a Cureulio (Kirby and Spence).
Fig. 6, Angustate ditto of Asilus (Meig). Fig. 7, Setigerous ditto of Sargus (ib.).
Fig. 8, Plumose ditto of Volucella (ib.). Fig. 9, Both of Ceria conopsoides seated
on a process of the frons (ib.). Fig. 10, Antenna of Chrysotoxum (ib.).
Fig. 11—13, Ditto of Bombylius (ib.) Fig. 14, Of Lophosia (ib.). Fig. 15,
Of Rhaphium (ib.). Fig. 16, Of Sybistroma (ib.) Fig. 17, Of Gonia (ib.).
Fig. 18, Mucronate ditto of Empis (ib.). Fig. 19 and 20, Auriculate ditto of
Parnus and Gyrinus. Fig. 21, Ramose ditto of Nepa. Fig. 22, Irregular
ditto of Cerocoma . Fig. 23, Ditto of Psychoda (Meig.). Fig. 24, A portion
of the antenna of Gastropacha trifolii. b, A portion of the branch to exhibit
the fine ramose hairs which form the fringe, the one strongly, the other slightly
magnified. Fig. 25, Fasciculate antenna of Callichroma alpinum. Fig. 26,
Antenna of a small Brazilian Saperda. Fig. 27 and 28, Feathery antennae of
Ceratopogon and Tanypus (Meig.). Fig. 29, Portion of an antenna with
kidney-shaped joints of Nephrotoma (ib.). Fig. 30, Irregular clavate antenna
of Agaon paradoxum (Dalman).

PI. IX. N. B. In Plates IX. — XIV., which explain the composition of the
thorax in the different orders, for the sake of distinction the prothorax is
coloured red , the mesothorax blue , the metathorax yellow , and the coxae green.
In all the figures, A indicates the pronotum, B the prosternum, b the omium,
C the inesonotum, D the scapula of anterior wing, D* of posterior wing,
E the mesosternum, F the metanotum, G the metasternum, H the parapleura,
I the pleura, K the coxae (generally of the posterior legs). All the figures are
original, and from drawings by the author.

(No. 1] exhibits parts of the thorax of Carabus glabratus. Fig. 1, Prothorax
from above. Fig. 2, Ditto from beneath. Fig. 3, Prosternum from the inner
surface, to exhibit the situation of the two weak internal processes. Fig. 4,
The omium. b , The external surface. 5% The reflexed margin which is
attached to the inner surface of the pronotum. Fig. 5, Lateral view of the
prosternum, c c, Its two internal scale-shaped processes, between which the
nervous cord lies. Fig. 6, Meso- and Metathorax seen from above. R R, The
rudimentary wings. 6, The same from beneath. S S, The first abdominal

DESCRIPTIONS OF PLATES.

639

segment. S* S*, The second ditto. K K, Coxae of the posterior legs
T T, Trochanters. Fig. 7, Anterior view of the mesosternum to exhibit the
two processes/, which form the fork, and between which the nervous cord lies
Fig. 8, Anterior wings of the scapula seen from the surface, b, The reflexed
margin which lies against the posterior wings. Fig. 9, Posterior wings of the
scapula seen from the surface, b *, The reflexed margin which lies against
the margin of the anterior wing, and forms the suture in which both meet
together.

[No. 2,] Parts of the skeleton of Dyticus. Fig. 1, View of the internal portion
of the head after the removal of the upper integument, a a, The two ridges
which proceed from the throat and enclose the cerebellum between them.

c, The tentorium or the transverse baud of connexion between the two ridges.

d, A second deeper-seated band, consisting of two halves, upon which the
anterior portion of the cerebellum rests, e e, Two hooked processes, which
proceed from the superior margin of the bands, and encompass the oesophagus
in front of the cerebrum. They serve for the insertion of small muscles which
retain the oesophagus. //, A horny ridge which runs beneath the frons from
one side of the head to the other, and to which the labrum is attached, g, The
labium, or, rather, its superior fleshy part, the tongue, h, A horny semicircular
bone, to which the tongue is attached ; it lies free in the flesh, and does not
come in contact with the integument of the head, b b, The orbits. Fig. 2,
The protliorax seen from beneath, b b , The omia. Fig. 3, The prosternum
from behind, a a, The jugularia which lie in the membrane of the neck, and
upon which the head revolves, b b, Internal processes of the prosternum which
encompass the nervous cord. Fig. 4, The omium seen from the surface.
b, The external surface, b*, The reflexed margin which lies against the
surface of the pronotum. Fig. 5, Prosternum from the side, b, The internal
processes. Fig. 6, Coxae, trochanters and femur of the intermediate leg, to
show the free articulating process, a, Audouin’s trochantinus. Fig. 7, Meso-
and metathorax from above. Fig. 8, The same from beneath. Fig. 9, Meso-
sternum separated from the parapleura, with its internal processes. This gives
the most perfect representation of the vertebra of an insect. E is the body of
the vertebra whence the arches proceed which encompass the nervous cord.
b b are the transverse processes. a forms the processus spinosus, consisting
of two halves. At the superior transverse process of the body the scapulae
articulate ; they correspond to the articulating surfaces of the ribs in the
vertebrae. Fig. 10, Anterior wing of the scapula(D). Fig. 11, Posterior wing
of the scapula (D*). b, The reflexed margin which forms the suture with
that of the anterior wing. Fig. 12, The connate coxae seen from the front to
exhibit the process springing from them. It ascends in a forwardly inclined
direction from the suture of both coxae, and then divides into four processes,

640

DESCRIPTIONS OF PLATES,

the two posterior of which again furcate, b b , The anterior processes, a a, The
posterior with their furcate branches **.

[No. 3,] Portions of the skeleton of Buprestis mariana. Fig. 1, Prothorax
from beneath. A A, Reflexed margin of the pronotum. B, Prosternum.
b b, The small round plates which correspond to the anterior wings of the
scapulae in Carabus and Dyticus. Fig. 2, The same from the front, a a, The
jugularia which lies in the membrane of the neck. Fig. 3, Prosternum from
the side. The internal processes are small, and stand forwards, g, The same
from within, a a, these processes. Fig. 4, Upper view of the meso- and
metathorax. Fig. 5, The same from beneath. Fig. 6 — 8, Mesosternum and
scapulas in their natural situation, b, Mesosternum (E E). Fig. 7, Anterior
wings of the scapulas (D D). Fig. 10, Metathorax from within to exhibit the
quadridentate process, b b, The anterior teeth, a a, The posterior. Fig. 11,
The same from the side. Fig. 12, Meso- and metathorax of Hister cadaverinus
seen from beneath. S, First abdominal segment. Fig. 13, The same from
above.

PI. X. [No. 1,] Fig. 1, Parts of the skeleton of Geotrupes nasicornis. Fig. 1,
Pronotum from beneath, the prosternum is removed, a a , The reflexed margin.
Fig. 2, Prosternum from beneath. Fig. 3, The same from the side, a, The
internal processes. Fig. 4, Meso- and metathorax from above. Fig. 5, Meso-
sternum with the scapulas. E, Mesosternum. D D, Ala anterior scapulas.
D* D*, Ejusd. ala posterior. Fig. 6, Meso- and metathorax from below.
Meso- and metasternum are here connate. Fig. 7, Mesosternum from within.
a a a, The three points of the processus internus. Fig. 8, The internal process
from the side, a a a, The three points. [No. 2,] Skeleton of Cetonia aurata.
Fig. 1, Meso- and metathorax from above. Fig. 2, The same from beneath.
Fig. 3, Prosternum and scapulae seen from the front. Fig. 4, The connate
sternum from within, a a, Proc. intern, raesosterni. b, Proc. intern, metast.,
each consisting of two divaricating lamellae, between which the nervous cord
lies. [No. 3,] Skeleton of Hydrophilus piceus. Fig. 1 , Pronotum from beneath.
Fig. 2, Prosternum ditto. Fig. 3, Mesonotum from above (the letter G is here
wrong). Fig. 4, Metanotum from above. Fig. 5, Sternum from without.
Fig. 6, The same from within, a, The internal processes of the mesosternum
which ascend to the scapulae, b b , Wings of the processus internus metasterni.
Fig. 7, The same from the side, a «, The pro. int. mesost. ascending as far as
the scapulae, b b , Both wings of the processus internus metast. d , This process
itself, e, A thin horny lamella which lies beneath the proc. g , An externally
visible aperture which indicates the point of division between the two parts of
the connate sternum. Fig. 8, Parapleurae from the inner surface, with the
tendon of the large extensor of the wing, a, The plate-shaped distension.

DESCRIPTIONS OP PLATES.

641

b , The central petiole which is affixed to the anterior main nervure of the
wing.

PI. XI. [No. 1,] Skeleton of Gryllotalpa vulgaris. Fig. 1, Pronotum from
above. Fig. 2, Prothorax from beneath, a a, The two stigmata which lie in
the membrane behind the prothorax, b, Aperture of the neck, being the
entrance to the prothorax, c, Posterior aperture, d d , Cavities for the coxae.
Fig. 3, Internal skeleton of the prothorax. A, Pronotum. B, Prosternum.
C, Descending keel of the pronotum, which divides into two furcating
lamellae, the anterior and posterior points of which are at E E and F F. With
the anterior ones, the T-shaped anterior distension of the sternum articulates,
and with the posterior ones, which again unite, the posterior apex articulates at *.
Besides which, two processes, D D, spring from the sides of the pronotum, which
meet at the anterior angles of the central carina near E E. A process, G, springs
on each side backwards from the posterior angles of the central carina, both of
which are retained by a bone upon which the crop rests, and which is connected
by muscles at * * with them. Fig. 4, Meso- and metathorax from above.
Fig. 5, Mesosternum from the side, lying free internally upon the external
plate E, the point bending backwards. Fig. 6, The same from beneath with
the backwards directed processes, the points are cut off. Fig. 7, The mesonotum
seen from the front to exhibit the prophragma, in which, at «, the aperture
to the aorta is found. Fig. 8, Lateral view of the meso- and metathorax.
ß, Stigma upon the limits of the meso- and metathorax. [No. 2,] Skeleton of
Gryllus migratorius. Fig. 1, Head from beneath, with the aperture of the
mouth distended anteriorly to exhibit the radiating tentorium (c c c ).
a a, Basal joints of the antennse. b b, The eyes. Fig. 2, Prothorax from front,
natural size, a a, The horny arch springing from the sides, which bow over the
aeetabulse of the cox®. Fig. 3, Meso- and metathorax from above, with dis-
tended but cut-off wings, c e, Prophragma. Fig. 4, The same from the side.
a a , Rudiments of the base of the wings, c, Prophragma. ß, Second spiracle of
the thorax. Fig. 5, The same from beneath. Fig. 6, Mesothorax alone seen
from behind. C, Mesonotum. DD, Scapulae. E, Mesosternum. a a, Remains
of the wing, c, Mesophragma with the aperture p for the aorta, d d, Internal
ridges, which indicate the suture of the wings of the scapulae, e e , Horny arch
spanned over the acetabulae. [No. 3,] Skeleton of Libellula. Fig. 1, Entire thorax
from above, with the remains of the wings. Fig. 2, The same from the side.

c, The free prophragma. /3, Second thoracic spiracle. Fig. 3, The same
from beneath. Fig. 4, Prehensile organ upon the second and third ventral
segments of the male Libellula. a a, Two moveable hooks which encompass
the points * * of the processes b b. c c, Processes of the second division of
the prehensile organ, between which the hook d lies, e, Third division of
that organ. Fig. 5, The same from the side. Fig. 6, Third division of the
prehensile organ, consisting of a large swollen knob, a, which at d is excavated,

642

DESCRIPTIONS OF PLATES.

and at the anterior ridge of which the hook b hangs by two joints. Fig. 7,
Central division of the prehensile organ, a a , The processes, b. The hook
between them raised. Fig. 8, First division of the same organ, consisting of
the anterior pieces, a a , which articulate at d d with the posterior ones, b 6,
and the hooks c c. Fig. 9, Apex of the abdomen of a male Libdlula.
Fig. 8, 9, 10, The same ordinal joints of the abdomen, a, The aperture to the
sexual organs.

PI. XII. [No. 1,] Skeleton of Cimbex variabilis. Fig. 1, Lateral view of the
thorax, a, Tegula which covers the first thoracic spiracle. d, Patagium
analogous to the anterior wing of the scapula, c, Scutellum. ß, Second
spiracle. Fig. 2, View of the thorax from above. yy, Ceachri. Fig. 3,
Mesonotum alone, a, Prophragma. d d, Patagia. e, Scutellum. Fig. 4,
Prosternum seen from behind, to show the internal processes a a. b b , Cavities
of the coxse. Fig. 5, The same from the side. Fig. 6, Mesosternum with its
lateral ascending wings. a a , Internal process divided into two points.
b b, Cavities of the coxae, e, Hook-shaped process, which originates from the
side of the sternum, and serves the muscles of the coxae for insertion.
[No. 2,] Skeleton of Scolia flavifrons. Fig. 1, Thorax from above, d d, Patagia.
c, Scutellum. ß ß, Second spiracles. Fig. 2, The same from the side,
a, First spiracle, ß, Second, d, Patagium. c , Scutellum. Fig. 3, The
same from beneath. * Aperture through which the tendon passes which holds
the abdomen. Fig. 4, Metanotum with the process to which the muscle is
attached, which, with the tendon proceeding from it, holds the abdomen.
Fig. 5, The same from the side. Fig. 6, Prosternum from behind.
a a, Acetabulae of the coxae, b by Internal processes. Fig. 7, Cavity, A, in
the metathorax, for the reception of the apex of the abdomen, a, Hole through
which the tendon passes, b b, Ball joints. Fig. 8, Cavity in the base of the
abdomen, which inserts itself in the cavity of the metathorax, a a, Sockets.
b b. Ball joints, c, Process to which the tendon is attached. Fig. 9, First
segment of the abdomen seen from the side. a, Process to which the tendon
is affixed. b, Socket for the reception of the ball joint of the metaphragma.
Cy Ball joint which is inserted in the socket of the metaphragma.

PI. XIII. [No. 1,] Thorax of Methoca ichneumonides, Lat. Fig. 1, Thorax
seen from above. A, Pronotum. c, Scutellum. F, Metanotum. Fig. 2, The
same from the side. B, Prosternum. E, Mesosternum. G, Metasternum, ß, Se-
cond spiracle. [No. 2,] Thorax of Myrmosa melanocephalay male. Fig. 1,
From above. Fig. 2, From the side, marked as above. [No. 3,] Superior view
of the thorax of Chrysis ignila. A, Pronotum. C, Mesonotum divided by
two furrows into three fields, c, Scutellum. d d, Patagia. F, Metanotum.
[No. 4,] Thorax of Cossus liyniperda. Fig. 1, View from above, e, Mesonotum.
D*, Patagium. d d, Frenum. c, Scutellum. F F, Metanotum. K K, Coxie

DESCRIPTIONS OF PLATES.

643

of the posterior legs. Fig. 2, Lateral view. A, Scale-shaped pronotum.

B, Prostemum. a, Cavity in which the first spiracle lies. C, Mesonotum.
c, Scutellum. D*, Patagium. D, Scapula. E, Mesosternum. 0, Cavity
of the second spiracle. F, Metanotum. G, Metasternum. K K K, Coxce.
[No. 5,] Thorax of Cicada Fraxini. Fig. 1, View from above. A, Pronotum.

C, Mesonotum. c , Scutellum. d d , Frenum. F F, Metanotum. Fig. 2,
View from beneath. B, Prosternum. E, Mesosternum. G, Metasternum.
ß ß, Scales beneath each of which the second spiracle of the thorax lies.
[No. 6,] Thorax of Lygceus equestris. Fig. 1, Prothorax from above. Fig. 2,
The same from beneath. Fig. 3, Meso- and metathorax from above.
C, Mesonotum. c, Scutellum. Fig. 4, The same from beneath. E, Meso-
sternum. ß ß, Cavities covered by scales, beneath which the spiracles lie.
G G, Metasternum.

PI. XIV. [No. 1,] Thorax of Tabanus bovinus. Fig. 1, View from above.
d d , Protrusions which take the place of the patagia. Fig. 2, View from the
side, a , First spiracle, indicating the boundary of the prothorax. B, Situation
of the prostemum. C, Mesonotum. c, Scutellum. d , The patagium.

E, Mesosternum. R, Base of the wing. S, Scale. F, Metanotum.

G, Metasternum. T, Poiser. ß, Second spiracle. H, Metaphragma

K K K, Coxae. [No. 2,] Thorax of Myopa testacea. Fig. 1, View from above.*

A A, Protrusions which indicate the prothorax (humeri of entomologists).
C C, Mesonotum. c, Scutellum. S S, Scales. T T, Poisers. F, Meta-
notum. Fig. 2, Lateral view. A, Humerus, a, First spiracle. C, Meso-
notum. c, Scutellum. E, Mesosternum. S, Scale. F, Metanotum.
G, Metasternum. T, Poisers. 0, Second spiracle. H, Metaphragma.

[No. 3,] Thorax of Semblis bicaudata. Fig. 1, Prothorax from above. Fig. 2,
The same from beneath. B, Prostemum. a a, Place of the first spiracle.
K K, Acetabulae. Fig. 3, Meso- and metathorax from above. C, Mesonotum.

F, Metanotum. Fig. 4, The same from the side, with the same indications.
Fig. 8, Pincers of a Forficula (De G.). Fig. 9, A Smynthurus seen from
beneath (De G.). a, The fork which produces the leap, b, Process upon the
mesosternum whence the filaments proceed. Fig. 10, Apex of the abdomen of
Staphylinus erythropterus. aa, The hairy styli. Fig. 1 1, Apex of the abdomen
of Blatta orientalis. a a, The circi. b b , Two other processes which proceed
from the ventral plate, c, The male organs withdrawn. Fig. 12, Apex of
the abdomen of a male Ephemera . a, The penis, b b, The two fangs which
are seated on the ventral plate, c c, The jointed fila proceeding from the
dorsal plate, the half of which is cut off. Fig. 13, Apex of the abdomen of
Machilis polypoda (Dumeril), with the hairy set®. Fig. 14, Apex of the
abdomen of Aphis, a a, The siphunculi.

PI. XV. N. B. The two arrows at the base of the wings indicate the course

644

DESCRIPTIONS OF PLATES.

of the current of the blood. Fig. 1, Wing case of Nepa cinerea, a , Clavus.

b, Hemielytrum. c, Appendix, d , Membrana. Fig. 2, Wing case of
Gryllus migratorius. A, Marginal cell, b, Vena radialis. B, Central cell.

c, Vena cubitalis. C, Sutural cell. Fig. 3, Wing of Dyticus. «, Vena

marginalis or radialis. b , Vena cubitalis or postcosta, also nervus internus.

The marginal space is in this and in all the following wings indicated by red,
and the sutural space by yellow. The former is bounded by the vein through
which the current of blood streams, and that of the latter by the one through
which it returns. Fig. 4, Wing of a Tenthredo. a, Vena radialis. 6, Vena
cubitalis. ß, Stigma, carpus, d d , Cellulge radiales, e e e, Cellulae cubitales.
Fig. 5, Wing of a bee. a, Marginal vein, b , Discoidal vein, d, Marginal
cell. e e , Cubital cells. c c, Discoidal cells, fffi Incomplete cells.
Fig. 6, Wing of a Tipula. Fig. 7, Wing of a Syrphus. Fig. 8, Wing of a
Tachina. Fig. 9, Wing of one of the smaller Muscidce. Fig. 10, Wing of a
Phora. Fig. 11, Wing of Hippobosca. All these figures are marked like 5.
Fig. 12, Anterior wing of Platypterix, ala falcata. Fig. 13, Posterior wing
of Papilio Podalirius, ala caudata. Fig. 14, Anterior wing of Orneodes
hexadactyla, ala digitata.

PI. XVI. Fig. 1, Anterior leg of Carabus. a , Coxa, b , Trochanter
c, Femur, d. Tibia. 2 S, Calcaria. e, Tarsus. Fig. 2, Anterior leg of
Ateuchus sacer. e , The terminal spine supplying the place of a tarsus.
Fig. 3, a , Intermediate leg of a butterfly, b , Abortive leg of the same.
Fig. 4, Swimming leg of Dyticus dispar. Fig. 5, Leaping leg of Haltica.
Fig. 6, a, Prehensile leg of Mantis religiosa. b, Prehensile leg of Nepa cinerea.
Fig. 7, Digging leg of Gryllotalpa vulgaris. The tarsus is three jointed.
Fig. 8, Fringed femur of an Andrena. Fig. 9, Supporting trochanter of
Carabus. Fig. 10, Double-jointed trochanter of a Pimpla. Fig. 11,
Lamellate tibia of a Lygceus. Fig. 12, Scutellate tibia of Crabro cribra-
rius, a. e* The five-jointed tarsus. Fig. 13, Brush-like tibia of Apis.
e, Planta. Fig. 14, The sole of Carabus fringed with spines. Fig. 15,
Cordate tarsal joint of Timarcha tenebricosa. Fig. 16, Triangular tarsal
joint of Copris lunaris. Fig. 17, Quadrate tarsal joint of Buprestis
mariana. Fig. 18, Bilobate tarsal joint of Callidium violaceum. Fig. 19,
Furcate tarsus of Xya. a, Spines on the tibia, e e , The furcate tarsus, con-
sisting each of one joint. Fig. 20, Tarsus with three distended joints of
Cicindela campestris. Fig. 21, Tarsus with four distended joints of Calosoma
sycophanta. Fig. 22, Tarsus with one distended joint of Hydrophilus piceus.
Fig. 23, Anterior tarsus of Dyticus dispar , a, from above, b , from beneath.
p p, The large patellulae. Fig. 24, Claw joint of Carabus , equal claws.
Fig. 25, Claw joint of Anisoplia fructicola. Fig. 26, Claw joint with very large
unequal claws of Rutila. Fig. 27, 6, Furcate claw of Melde divided near the
surface, a, Furcate claw of Anisoplia horticola, divided near the ridge.

DESCRIPTIONS OP PLATES.

645

N. B. It is only the external larger claw that is thus divided, and not, as the
drawing indicates, the smaller one also. Fig. 28, Dentate claw of Melolontlia.
Fig. 29, Dentate claw of Ornithomya. Fig. 30, Serrate claw of Cistela.
Fig. 31, Claw joint of Lucanus cervus. a «, The large claws, b , The pseudo
claw. Fig. 32, Claw joint of Tachina fera. a a , The serrate claws, b b, The
plantulae. Fig. 33, Claw joint of Laphria flava, a a , The claws, b b, The
plantulae. c, The pseudo claw. Fig. 34, Tarsus of Xenos, without claws, but
with soft plantulae. Fig. 35, Hairy plantula of Lamia. Fig. 36, Plumose
plantula of Zabrus. Fig. 37, Spongy plantula of Timarcha tenebricosa.
Fig. 38, Tarsus cryptopentamerus of Cerambyx heros. 1, First tarsal joint
(metatarsus) ; 2, second tarsal joint (phalanx prima) ; 3, third bilobate tarsal
joint (phalanx secunda); 4, abortive fourth tarsal joint (arthrium); 5, claw
joint. Fig. 39, Tarsus cryptotetramerus of Coccinella. 1, First tarsal joint;
2, second deeply excavated foot joint; 3, arthrium ; 4, claw joint.

PI. XVII. Fig. 1, Internal structureless folded tunic of the ilium of
Hydrophilus piceus. Fig. 2, Second tunic of the ilium of the same beetle
beset with ridges, teeth, and stars. Fig. 3, Third or muscular tunic, with the
ventral glands, which lie in a transparent case, of the same. Fig. 4, Third or
muscular tunic of Dyticus marginalis. Fig. 5, Second tunic of the crop of
the same beset with horny ridges that form regular meshes. Fig. 6, Transverse
section of the membrane of the crop of the same. a, Internal layer beset with
ridges, b , Muscular tunic. Fig. 7, Tunic of the oesophagus of the same
with undulating horny ridges. Fig. 8, Proventriculus of the same. It is
excavated in the form of a tunnel, and supplied with four teeth, which are
broad above and narrow below. 3, Intestinal canal of the larva of Vespa crabro
(Suckow). A, (Esophagus. D, Ventriculus. H, Caecum. K K, Biliary
vessels. Fig. 10, Intestinal canal of Vespa crabro ( ib .). A, (Esophagus.
C, Crop. D, Transversely striated ventriculus. E, Ilium with four longi-
tudinal stripes. H, Colon with horny rings.

PI. XVIII. Fig. 1, Intestinal canal of Aphrophora spumaria (ib.).
A, (Esophagus. D, Crop. D*, First division of the ventriculus. DD**,
Second division, which returns to the crop. E, Ilium. H. Colon. K K, Biliary
vessels. Fig. 2, Intestinal canal of the maggot of Musca carnaria (ib.), marked
the same as above. N N are the salivary vessels with their simple outlets, O.
Fig. 3, a, A portion of the biliary vessel much magnified. Fig. 3, Intestinal
canal of the perfect fly (ib.). Fig. 4, Intestine of the caterpillar of Gastropacha
Pini (Suckow), marked similarly. F is the clavate gut. O O are the spinning
vessels. Fig. 5, Intestinal canal of Pontia Brassicce (Herold). C, The sucking
stomach. G, The ccecum. The rest as before.

PI. XIX. Fig. 1, Intestinal canal of the larva of Calosoma sycophanta

646

DESCRIPTIONS OF PLATES.

(original), marked as before. H is the internally longitudinally folded colon
to which the last segment of the larva is still attached. Fig. 2, Intestinal
canal of the perfect beetle (Suckow). D is the ventriculus, the anterior half
of which is covered with the pancreas, and the posterior portion, D*, with
glands. Fig. 3, Intestinal canal of the larva of Dyticus marginalis (orig.),
marked the same. Fig. 4, That of the perfect beetle, as before, the ventriculus
anteriorly covered with the pancreas.

PI. XX. Fig. 1, Intestinal canal of Cetonia aurata (Ramd.). D, The
pancreas covers the ventriculus with three coronets. F, The clavate gut.
Fig. 2, Ditto of the perfect insect ( ib .), as before. Fig. 3, Ditto of Cimex
rufipes (Trevir.). a a and ß ß are the sets of the proboscis whence the vessels
y y originate which open into the commencement of the ventriculus. b b , The
salivary vessels and glands. I), The first stomach with the two-folded bodies
($ S) at its orifice (this supplies the place of a crop). D*, The second stomach
(supplying the place of a proventricul us). D**, The third stomach, forming,
as it were, a second crop in front of the true ventriculus. D***, The ventri-
culus, consisting of four contiguous tubes. The rest as before.

PI. XXI. Fig. 1, Intestinal canal of Gryllus migratorius. Lateral view.
a «, Four of the six blind tubular appendages at the orifice of the stomach
(pancreas), n, Nervus sympathicus. Fig. 2, The same opened. B, The
crop with the rows of teeth. **, Spot where the blind appendages open.
D, Ventriculus. ****, Spot where the biliary vessels open; the rest the
same as before. Fig. 3, a b , Two rows of teeth which are found within the
crop much magnified. Fig. 4, Raised longitudinal ridges beset with teeth
within the lower portion of the crop. Fig. 5, The processes, b £, of the internal
tunic of the stomach, a a, which thrust into the blind appendages and their
cavities, and open at C C into the intestine. Fig. 6, 'the portion of the intestine
where the blind appendages open, a a, their apertures ; these cut off, to show
their internal volume, c c, V-formed horny teeth, which form the proventriculus
Fig. 7, (Esophagus and crop of Gryllotalpa vulgaris (J. Muller). A, (Eso-
phagus. B, Crop. C, Continuation of oesophagus. D, Proventriculus.
E E, Blind bags which open into the commencement of the ventriculus.
G, Ventriculus. a, Cerebrum, b 6, Nervous cords which form the first
ganglion, c, of the Sympathie system. d d, The Sympathie nerves.
e, Branch of it for the crop, f, Second or connecting ganglion. $r, Branch
for the proventriculus. Fig. 8, Transverse section of the proventriculus of
Termes fatalis. a a, Projecting horny plates, b b b, Six fasciculi of muscles
which close it. Fig. 9, Lateral view, a, Space before the proventriculus, crop.
b , The proventriculus seen through the contracted orifice of the ventriculus.
d, Ventriculus. Fig. 10, Opened proventriculus of Termes fatalis. a a, Twelve
horny plates, which are alternately supplied with strong fasciculi of muscles,

DESCRIPTIONS OF PLATES.

647

b b , which unite to form the sphincter of the stomach. Fig. 11, Orifice of the
stomach of Lamia cedilis. a a, Four teeth, which have two fine horny ridges.
b b , Ridges of the crop, c, Ventriculus. Fig. 12, Salivary vessels of Locust a
viridissima. a , Tongue from beneath, b b , Outlets of the glands, c c, Glands.
Fig. 13, Mandibles and salivary vessels of the caterpillar of Gaslropacha Pini
(Suckow), a, Mandible, b , Gland, aperture of the salivary vessel, c, Muscle
of the mandible, d d, Salivary vessel. Fig. 14, Urinary organ of Dyticus
marginalis. a a, Secreting vessel, kidney, b , Urinary bladder, c, Evacuating
duct. Fig. 15, Salivary vessels of Reduvius personatus (Ramd.). a, (Eso-
phagus. b , Duct of the salivary glands, c c, Longitudinal glandular bodies.
Fig. 16, Salivary vessel of Pulex (Ramd.), vesicular glands, b , Excretory
duct.

PI. XXII. Fig. 1, Single salivary vessel of Nepa cinerea (Ramd.). a, Duct.
b , Glands, c, Glandular vessel. Fig. 2, Second salivary vessel of ditto
(ib.). a b , Double duct of the auxiliary gland, d , Auxiliary gland, ee, Chief
gland. Fig. 3, Salivary vessel of Blaps (Leon Duf.). Fig. 4, Ditto of
Tabanus (Ramd.) Fig. 5, Ditto of Cicada (Leon Duf.). Fig. 6, Ventral
salivary glands of Leptis (Ramd.). a a , The two glandular bags, b, (Eso-
phagus. c , Outlet of the sucking stomach, d , Commencement of the ventri-
culus. Fig. 7, Ventral salivary glands of Bombylius (ib.), the same. Fig. 8,
Ditto of Chrysotoxum (Ramd.), the same. Fig. 8*, Lateral view of the heart
of Melolontha vulgaris (Straus-Durck.). a a, Orifices of the heart, 12.
g, Ventriculi. B, End of the heart. C, Aorta. Fig. 9, Commencement of
the heart, with the muscular wings (ib.). a a, Muscular wings, b b, Orifices
in them, in front of each aperture of the heart. Fig. 10, Spiracle of the
abdomen of Dyticus marginalis. Fig. 11, Portion of a trachea, a a, External
tunic. b b, Spiral filament which forms the second tunic. cc, Third, or
mucous tunic. Fig. 12, A portion of the tunic of the air-bag of Musca
vomitoria, very much magnified.

PI. XXI II, Fig. 1, Spiracle of Oryctes nasicornis , seen from the front, a a,
The projecting margin, b b, Horny plates, which form its lips, c, Aperture.
Fig. 2, The same, removed from the contiguous parts, and seen from the side.
a, Projecting margin, bb, The separated integument in the vicinity of the
spiracle, c c , Posterior projecting margin of the spiracle, d d, The two horny
triangles, which lie on one side of the main stem of the trachea, which join
at *, and are moved by the broad muscle, e. fff, Branches of the tracheae.
Fig. 3, The same, from beneath, a a, External projecting margin, b b, Sepa-
rated integument, c, Spot where the apex of the lower triangle articulates with
the margin of the spiracle that projects inwardly, d, The lower horny triangle.
fff, Steins of the tracheae. Fig. 4, Spiracle of the larva of Cetonia aurata.
a a, The external darkly-coloured margin, which is decorated with paler ellip-

u u

648

DESCRIPTIONS OF PLATES,

tica! spots, b b} The central paler horny plate, c, The raised margin of the
true aperture, d d, Branches of tracheae. Figs. 5 — 11, Ovipositor of Sirex
juvencus. Fig. 5, Last abdominal segment, with the ovipositor, A. B B,
Lateral margins of the last largest segment. Fig. 6, Apex of the abdomen,
from the side. The ovipositor, b, projects from the two valves, a. Fig. 7, Apex
of the ovipositor, seen from above, c, The divided dentate apex of the sheath.
d d , The two dentate setae within the sheath. Fig. 8, The ovipositor, from the
side, c, The upper channel, d, The single lower seta. Fig. 9, From beneath.
c c, Sheath, dd , Setae. Fig. 10, One seta, to exhibit the shape of the teeth
upon it. Fig. 11, Transverse section of the ovipositor, a a, The external
valves, c, The sheath, d d, The setae, e, Central free channel. Figs. 12 — 14,
Ovipositor of Pimpla. Fig. 12, Apex of the organ, covered with short teeth.
a, The upper channel, b, The fine seta. Fig. 13, Section of the mere ovi-
positor. a, Channel, b , Seta, c, Canal. Fig. 14, Section of the ovi-
positor, with the valves. a, Channel, b, Seta, c c, Valves, e, Canal. Figs.
15 — 18, Ovipositor of Cynips quercifolia. Fig. 15, Last bent segment, with
the two hairy processes originating from the internal surface. Fig. 16,
The ovipositor, a a , Valves, b b , External channel of the setae, c, Central
finer seta. Fig. 17, The external, b b , and the central seta, c , alone.
Fig. 18, Section, a a , Valves, b b , External setae, e, Central one.

PL XXIV. Figs. 1 — 7, Ovipositor of Cicada Fraxini. Fig. 1, Apex of
abdomen. A, Last dorsal segment. D, Last ventral segment. B, Basal
joint of the sheath of the ovipositor. C, Terminal joint. Fig. 2, Ovipositor
with the valves from beneath. B B, Basal joints of the valves. C C, Terminal
joints. D, The ovipositor. Fig. 3, Apex of the ovipositor from beneath.
a a, Superior distended sheath, with teeth on the margin, b b, The lower setae
pushed upwards, so that they project beyond the apex of the sheath. Fig. 4,
Setae from the inner side, to show the central channel. Fig. 5, Apex of the
sheath from above, toothed on the margin, furrowed in the centre, emarginate
at the apex to receive the points of the setae, which form the true apex of the
ovipositor. Fig. 6, Section, a a , The valves, b b , The sheath, c, The setae.
Fig. 7, Section of the mere ovipositor, a a, Sheath. b, Seta. Figs. 8, 9,
Ovipositor of Cimbex variabilis. Fig. 8, The valves opened from beneath.
A A, The last dorsal segment, a a, External valves, b b, Internal valves, or
saws, c, Central short process. Fig. 9, An internal valve, or saw, from its
external surface, b, Furrow, by means of which the external surface is divided
into two halves, a, Lower more finely serrated. b, Superior more coarsely
serrated surface. Figs. 10 — 15, Ovipositor of Locusta. Fig. 10, Apex of the
abdomen of Locusta viridissima. A, Last dorsal segment. B, Last ventral
segment. C, Ovipositor. Fig. 11, One half of the sheath seen from the
exterior of Locusta ephippiger . Fig. 12, The same from the inner surface,

a, Superior half of the valve, c, Lower half, b, Central, smaller, inner valve

DESCRIPTIONS OP PLATES.

649

of the same side. Fig. 13, External view of the apparatus of Locusta viridis -
sima. a, Upper half, c, Lower half. Fig. 14, The same from within, «,
Upper half, c, Lower half. 6, Internal valve, indicated here only as a project-
ing ridge, Fig. 15, the jointed ovipositor of Chryi^{ Kirby and Spence).

PI. XXV. Figs. 1 — 4, Male organs of Carabus glabratus. Fig. 1, Prepuce
from above, as taken from the ventral cavity, a, The horny ridges which dis-
tend the bag of the prepuce, b , The process of the prepuce, in which the penis
lies, c, Apex of this process, into which the vasa deferentia extends, d , Last
dorsal segment. Fig. 2, The same from beneath, a a, The horny ridges of
the prepuce, b , The horny plate which lies in the lower portion of the prepuce,
c, Process in which the penis lies, d, Last dorsal segment. Fig. 3, Penis from
above, with a, lateral moveable process, b , in which muscles are inserted.
Fig. 4, The same from beneath, a, Aperture of the penis, whence the sperm
flows. Figs. 5 — 10, Male organs of Dylicus marginalis. Fig. 5, View of them
beneath, with the last divided ventral plate. A A, The two halves of the ventral
plate. BB, Muscles whereby they are affixed to the preceding one. C C,
Horny ridges, which partly serve these for insertion. D D, Muscles which
unite the transverse ridge with the ventral plates, a, A horny ring lying
beneath in the prepuce, y g, Muscles that move the penis. /, Vasa deferentia.
Fig. 6, Penis and prepuce separated from the last ventral plate, seen from
beneath, a, A horny ring that distends the prepuce, b, Horny plate which
lies in it. i, Membranous portion of the prepuce, Sheath of the penis,
e, Penis, g g , Muscles which move the penis. /, Vasa deferentia. Fig. 7.
The same from above, a a, Horny ring of the prepuce, running at the margin,
and connected with the penis by muscles, h h. i, Membranous portion of the
prepuce, k , Horny plate lying in the upper part of the prepuce. /, Horny
scale to which the ends of the horny arch of the prepuce are attached, e , Penis.
g g, Muscles which move the penis, /, Vasa deferentia. Fig. 8, The same
seen from the left side, a, Horny ring of the prepuce, b, Horny scale lying
in the lower portion. The rest as in the preceding. Fig. 9, The penis, after
the removal of the prepuce, a a , Membranous portion of the prepuce, which is
drawn back by horny ridges, 6, which are connected witfi the horny ring of the
prepuce c c, by means of muscles, at its upper margin, dd. Valves of the
penis, e, Penis. Fig. 10, Penis, quite free, a, Ridge which lies in the
penis, and closes its aperture, b , Low er channel, in which the ridge or bone
lies. Figs. 11 — 14, Male organs of Hydrophilus piceus. Fig. II, Prepuce
from above. M, The removed colon, d d, Last dorsal segment, with three
fenestrations, b b , Horny ring which distends the prepuce. E E, Sheaths of the
penis. F, Penis, j, \ Vasa deferentia, surrounded by the membranous portion
of the prepuce. Fig. 12, The same, from beneath, a, Horny plates, which
lie in the lower portion of the prepuce, whence the ridges proceed which affix
themselves to the apex of the last ventral plate, e e. c c, Other horny ridges,

u u 2

650

DESCRIPTIONS OF PLATES.

which proceed from the horny arch, b b, As fig. 11. d d , Last dorsal segment.
EE, Sheath of the penis. F, The penis. Fig. 13, The free penis, from above,
more magnified than fig. 12. A A, Reflexed margins of the horny plate.
A, As in fig. 14. B, Membranous portion of the penis. E E, Sheaths of the
penis, consisting of horn. F. Penis, provided in the middle and on the margin
with horny ridges. Fig. 14, Free penis, from beneath. A, A cordiform horny
plate, to which the sheaths are attached. E E, The sheaths of the penis.
F, Penis, with the aperture X, which is surrounded by a horny arch, whence a
ridge proceeds.

PI. XXVI. Figs. 1, 2, Sexual organs of Callichroma moschatum. Fig. 1, A,
Prepuce, supported by a horny ridge, C, which distends into a horny plate, B,
upon the upper surface of the prepuce. I), Penis. E, Vasa deferentia. F,
Ridge, by means of which the penis is pushed forwards. G, Last ventral
segment. Fig. 2, Free penis, seen from the left side, a, Lower horny tip of
the penis, b , Upper ditto, c, Vasa deferentia. Figs. 3—7, Male organs of
Blatta orienlalis. Fig. 3, View from above, a , Superior horny plate covering
them. &,Left. c, Right, d, Penis. Fig. 4, The same from beneath, c, Right
horny plate, b, Left, a, Upper, d, Penis. Fig. 5, The superior covering
plate, consisting of several homy pieces, and provided with a hooked process.
Fig. 6, The right covering plate, composed of two pieces, a and b. Fig. 7,
The left covering horny plate, with the penis, a a, Ridges, which enclose the
penis between them, b , The upwards bent penis, furnished at the end with a
hook. Figs. 8— 10, Male organs of Cimbex variabilis. Fig. 8, From below.
a a , The external sheaths, each consisting of a lower (a) horny and a superior
(a*) membranous portion, b &, The penis, likewise consisting of two valves.
Fig. 9, The left half of the sexual apparatus, seen from without. a, Horny
basal portion of the sheath, b , Membranous appendage, c c, Halves of the
valvular penis. Fig. 10, The same from within, marked similarly, d , Outlet
of the vasa deferentia. Figs. 11 — 13, Male organs of Vespa Gerfnanica.
Fig. 11, Seen from beneath, a a, External sheaths, b 6, Internal sheaths of
the penis, c, Penis. X, Aperture for the vasa deferentia. Fig. 12, Penis,
from the side, distended like a spoon, anteriorly, c, with a barb, a, by which
it hangs attached during copula. Fig. 13, The same, from above, marked
similarly, b. Internal passage of the penis. Figs. 14 — 17, Male organs of
Deilephila Galii . Fig. 14, Lateral view of the whole apex of the abdomen.
a a, Horny ring to which the external sheath is affixed, b , External sheath
of the left side, with the hooked appendage ( b *). c, Penis, d, Horny process,
into which the colon passes, e, Anus. Fig. 15, Sheath of the right side
seen from within. Fig. 16, Free penis, a, with the aperture c, and the
muscles b fe, which attach it. Fig. 17, Anterior aperture of the penis, seen from
above. — Figs. 18, 19, Male organs of Cercopis vulnerata, 111. Fig. 18, The
sexual apparatus, enclosed in valves, seen from the left side. Fig. 19, The

DESCRIPTIONS OP PLATES.

651

opened sexual apparatus, seen from above. The external valves are removed.
a a , The internal valves, b b , The horny penis, consisting of two parts, bent
outwards.

PI. XXVII. Fig. 1, Ovaria of Ephemera marginata. Fig. 2, Of Phasma
gigas (Müller). Fig. 3, Ditto of Gryllus migratorius. Fig. 4, Ditto of Meloe
proscarabeus. Fig. 5, Ditto of Gryilotalpa vulgaris (ib.). Fig. 6, Ditto of
Lepisma (Trev.). Fig. 7, Internal sexual organs of Hippobosca (L. Duf.).
a a , Ovaries, b, Uterus, cc, Conducting vessels. Fig. 8, Ovary of Anthi-
dium (Suckow). Fig. 9, Ditto of Tinea Evonymella (ib.). Fig. 10, Ditto of
Musca carnaria (ib.). Fig. 11, Ditto of Aphrophora spumaria (ib.). Fig. 12,
Ditto of Lucanus parallelopipedus (ib.). Fig. 13, Uterus without appendage
of Tipula crocata (ib.). Fig. 14, Ditto, with an appendage of Anihidium mani-
catum. a, The spermatheca (ib.). Fig. 15. The same of Hydrophilus piceus
(ib.). a , The spermatheca, into which the serpentine gum-vessel evacuates.
Fig. 16, The same of the Melolontha vulgaris (ib.). a , Spermatheca. b , gum-
vessel. The pockets are at the end of the sheath, into which the knob of the
penis inserts itself. Fig. 17, The same of Xylocopa (ib.). a, Spermatheca.
b, Gum-vessel. Fig. 18, The same of Sirex (ib.). a , Spermatheca, with the
two ears, b, Gum- vessel. Fig. 19, The same of Harpalus ruficornis. a ,

Sack-shaped distended sheath, b, Gum-vessel.

PI. XXVIII. Fig. 1, Uterus of Lucanus (Suckow), a, Spermatheca. d d,
Double gum-vessel. Fig. 2, Ditto of Gryilotalpa vulgaris (ib.). a, Sperma-
theca. b b, Gum-vessels. Fig. 3, Ditto of Lepisma (Trev.). b b, Gum-bags.
Fig. 4, Duct of the internal genitalia, with its appendages, of Gastropacha Pini
(Suckow), a, Spermatheca, with its narrow duct, b b, Glue-vessel, forked
above, beneath distended into a bladder, c c, Second secreting vessel, probably
a urinary organ, corresponding to the poison vessel of the Hymenoptera. a ,
Colon and ccecum. Fig. 5, Poison-vessels of Vespa crabro (ib.). a a , Secret-
ing vessels, b, Poison-bladder. Fig. 6, The same of Apis mellifica (Swamm.).
a a, Secreting vessels, b , Poison-bladder.

PI. XXIX. Fig. 1, United testes, with the two outlets, of Pontia Brassicce
(Herold). Fig. 2, Testes of LibeUula (Suckow). Fig. 3, Ditto of Aphrophora
spumaria (ib). Fig. 4, Ditto of Tipula crocata (ib.). Fig. 5, Ditto of Ranatra
linearis (ib.). Fig. 6, Half of the poison vessel of Apis mellifica. Fig. 7,
Testes of Dyticus marginalis. a , Large knob. b, Small knob of the duct.
Fig. 7, b, Testes of Silpha obscura (L. Duf.). Fig. 8, Ditto of Hydrophilus piceus
(Suck.). Fig. 9, Ditto of Trichodes (ib.). Fig. 10, Ditto of Locusta viridis-
sima. Fig. 11, Ditto of Staphylinus (L. Duf.). Fig. 12, Ditto and duct of
Musca deviens (Suckow). Fig. 13, Ditto of Semblis bicaudata (ib.). Fig. 14,
Ditto of Apate (L. Duf.). Fig. 15, Ditto of (Edemera (ib.). Fig. 16, Ditto

652

DESCRIPTIONS OF PLATES.

of Pimelia ( ib .). Fig. 17, Ditto and duct of Lytta vesicatoria (Brandt).

a, Testes, b, First gum- vessel, b b, Second ditto, a*, Bag-shaped distension
at the connecting point of the duct. Fig. 18, Testes of Lamia cedilis. Fig. 19,
Ditto of Prionus (L. Duf.), Fig. 20, Ditto of Cicada (ib.).

PI. XXX. Fig. 1, Testes of Nepa cinerea (Swamm.). Fig. 2, Ditto of Melo-
lontha vulgaris (Suckow). Fig. 3, Auxiliary testes of Hydroph. piceus (ib.).
Fig. 4, Ditto of Locusta viridissima. a, Superior fasciculus of vessels, b,
Retainer, clothed on the surface with small processes, into which the duct, c ,
opens, d, Sperm bladder. Fig. 5, Ducts of the genitalia of Donacia aquatica
(Suckow), without appendages. Fig. 6, Ditto of Phryganea oleracea. a, Vasa
deferentia. b. Vesica seminalis. Fig. 7, The same of Dyticus marginalis,
marked the same. Fig. 8, The same of Apis mell. (Brandt), a* a*, Vesica
seminalis. b b, Clavate gum-vessels. Fig. 9, The same of Melolont.ha vul-
garis (Suckow), a a. Ducts of the vesica seminalis. b b, Gum-vessels, with
their distension. Fig. 10, The same of Hy dr ophilus piceus (ib.). a a, Vasa
deferentia. a * a *, Vesica seminalis. a a, Ends of the auxiliary testes.
b * b*, The first furcate gum-vessel, b b, The second simple ones. Fig, 1 1 , The
same of Lamia cedilis. a a. Vesica seminalis. b. Furcate gum-vessel, with
unequal branches. Fig. 12, Organs of Vanessa Urticce , male (Swamm.).
a, United testes. a* a* Vasa deferentia, into which the gum-vessels, b b,
open. Fig. 13, Gum-vessel of Calosoma sycophanta (Suckow). a , Vasa
deferentia of one side, which opens into the gum-vessel (b b) of the side, that
of the other side and the ductus ejaculatorius is cut off. Fig. 14, Ducts of
the genitalia of Tipula crocata (Suckow), a a, Vasa deferentia. b, Gum-
vessels.

PI. XXXI. Fig. 1, A portion of the hard membrane of the brain of Dyticus
marginalis. Fig. 2, Brain of the caterpillar of Cossus ligniperda (Lyonel).
A, Cerebrum. B, Cerebellum, a a. Nerves of the eyes, bb, Of the antenna.
c, Cord round the oesophagus, proceeding from the cerebrum, d d , Cord con-
necting the cerebrum and cerebellum, e e, Nerves of the mandibles, the
branches of the second nerve of the lip (g g ), whence a branch for a muscle, N,
originates, ff, Nerves of the maxillae, gg, Second connecting nerve of the
labium, of which the nerve of the mandible is a branch, g* g*, First nerves
of the labium, which give off a branch, M, to the muscles of the maxillae.
O O, Nerves of the muscles of the mandibles and antennae. P P, Nerves of the
muscles of the mandibles. R R, Nerves that distribute themselves at the
posterior portion of the skull. SS, Nerves of the muscles of the neck, which
pass into the thorax. V V, Connecting cords of the cerebellum and first
thoracic ganglion. D, The frontal ganglion, formed of the two branches, E Er
whence the Sympathie nerve, F, originates. Fig. 3, Cerebrum of the same
caterpillar (ib.). E E, Branches to the frontal ganglion. O, Nerve of the

DESCRIPTIONS OF PLATES.

653

muscles of the mandibles, bb, Nerves of the antennse. a a, Nerves of the
eyes, cc, Cord of the oesophagus. PP, Nerves of muscles. A A, Small
ganglion of the Sympathie nerve. B B, Branches to ditto. F, Nervus sym-
pathicus (which Lyonet did not discover here). Fig. 4, Brain of Melo-
lontha vulgaris (Straus). A, Cerebrum. B, Cerebellum, a a, Optic nerves.
b b, Nerves of the antennse. d d, First ganglion of the Sympathie system.
G G, Second ganglion. D, Frontal ganglion, e e, Nerves of the mandibles.
ff, Nerves of the maxillse. Fig. 5, Cerebellum alone ( ib .). ee, Nerves of
mandibles, ff, Ditto of maxillae, k k , Connecting cord with the cerebrum.
hh, Connecting cords to the first thoracic ganglia. Fig. 6, Cerebrum of
Gryllus migratorius , with the Sympathie system seen from above. A A, Optic
nerves. BB, Nerves of the antennse. a, Frontal ganglion, b, First ganglion,
in which the odd (unpar.) nerve terminates, c c, The large ganglia. ee, The
small ditto, whence the Sympathie nerve originates by two branches, which
again unite at d* and d *. e e, Small ganglia upon the oesophagus, //, First
ganglion upon the crop, g g , Second, which lies at the end of the crop.
h h , Nerves which pass between the blind appendages. Fig. 7, Brain of
Gryllus migratorius, seen from the front. A A, Optic nerves, a a, Nerves
which pass to the frontal ganglion. b b. Nerves of the antennse. a* a* a *,
Nerves to the ocelli, dd, Connecting cords between the cerebrum and cere-
bellum. d *, The connecting cord of these. B, Cerebellum, ee, Nerves of
the mandibles, ff. Nerves of the maxillse.

PI. XXXII. Fig. 1, Brain of the larva of Calosoma sycophanta. A, Cere-
brum. a a, Optic nerves, bb, Nerves of the antennse. d d. Branches to the
frontal ganglion. D, Frontal ganglion. F, First ganglion of the Sympathie
system, the posterior one I have not discovered. B, Cerebellum. ee. Nerves
of the mandibles, ff, Nerves of the maxillse. gg, Nerves of the labium.
Fig. 1, B, Commencement of the ganglionic ventral cord of the same larva.
k , Cerebellum, h h , Auxiliary counecting cord, with the first thoracic ganglion.
n n. Auxiliary ganglia. A A, Nerves of the anterior legs. L, First thoracic
ganglion, i i, Auxiliary connecting cords of the first and second ganglia,
forming small ganglia, mm. kk, Auxiliary connecting cords between the
second and third ganglia. M, Second thoracic ganglion. N, Third. O, Fourth.
pp, q q, rr, ss, Nerves of muscles. BB, Nerves of the intermediate legs.
C C, Nerves of the posterior legs. Fig. 2, The ventral cord of Dyticus mar-
ginalis. A A, Nerves of the anterior legs. B B, The intermediate ones.
C C, The posterior ones. Fig. 3, Ventral cord of the larva of Eristalis
ienax. Fig. 4, Ventral cord of the fly Erist. tenax. a a, Connecting cords
with the cerebellum. A A, Nerves of the anterior legs. B B, Of the inter-
mediate. C C, Of the posterior. b b , Branches of the muscles which pass
into the abdomen, d, First abdominal ganglion, c c , Branches of it. e, Second
abdominal ganglion, ff, h h, gg, Brauches of it to the genitalia and other

654

DESCRIPTIONS OF PLATES.

internal organs. Fig. 5, Cerebrum of Vespa Germanica, a a a, Nerves to
the ocelli. A A, Optic nerves. B B, Nerves of the antennae, cut off. c,
Branch to the cerebellum. Fig. 6, Cerebrum and Sympathie system of the
caterpillar of Liparis Mori (Brandt). A A, Nerves of the eyes. B B, Nerves
of the antennae. C C, Hemispheres of the cerebrum, a a aa, Nerves which
originate from the frontal ganglion and its branches, b* b*, First ganglion
of the oesophagus. b** b **, Second ganglion of the oesophagus. /, Nervus
sympathicus. d, Its first ganglion, e, Its second ganglion. Fig. 7, The
same in the developed moth, similarly marked. Fig. 8, The same of Meloe
proscarabeus (Brandt), similarly marked.

THE END.

BRADBURY AND EVANS, PRINTERS, WHITE FRIARS.

I-’LAT E

PLATE

PLATE 3.

PLATE 4-.

PLATE 5.

PLATE 8.

ins.

PLA.TE 9.

PLATE 10

TLATE II.

PLATTS 12,

PLATE 13.

PLATE 14;.

PLATE 15,

PLATE 16 .

PLATE 18.

PLATE 22.

PLATE 23.

PLATE 26.

PLATE 28

PLATE 29.

PLATE 31.

PLATE 32.

a- 4

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