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MANUAL OF ENTOMOLOGY, 



- 









MANUAL OF ENTOMOLOGY, 



TRANSLATED FROM THE GERMAN OF 



DR. HERMANN BURMEISTER, 



BY 



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

WITH ADDITIONS BY THE AUTHOR, AND ORIGINAL NOTES AND PLATES 

BY THE TRANSLATOR. 




MORMOLYCE PHTLLODES. 



LONDON : 

EDWARD CHURTON, PUBLIC LIBRARY, 26, HOLLES STREET. 

1836. 



LONDON : 

tND EVANS, PRINTERS, IVIltTFFIUARS. 



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. 

i 

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 



VI 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. 



PAGF. 

Introduction Definition and Compass of Entomology, 14 . 1 



FIRST DIVISION. 

GENERAL ENTOMOLOGY. 



FIRST SECTION. ORISMOLOGY. 

Its Definition and Compass, 57 . . . . b 

FIRST CHAPTER. 

General Principles, is 13 . . 7 

SECOND CHAPTER, 

General Orisraology, $14 . ,11 

I. Form, 1521 . . . 11 

II. Quality, 2224 < . . .16 

III. Clothing, 25, 26 .19 

IV. Colour, 27 38 . 20 
V. Measure, 39 42 . . . 2H 

VI. Affixion, Direction, 43 45 , . 2 




Vlll TABLK OF CONTENTS. 



THIRP CHAPTER. 

PACK 

Partial Orisiuology, 46, 47 . 30 

I. The Egg, 48 50 . . 31 

II. The Larva, $$51 58 . . 33 

III. The Pupa, 59 64 . 43 

IV. The Imago, 65 . 48 

1. The Head, $66 72 . . 49 
The Mouth, 6870 . .51 
The Eyes, 71 .62 
The Antenna;, 72 . 63 

2. The Thorax.. 7378 . 71 

Organs of Motion on the Thorax. 

A. The Wings, 79, 80 .91 

B. The Legs, 8183 . 100 

3. The Abdomen, 84, 85 . . 108 



SECOND SECTION. ANATOMY. 

Idea and Subdivision of it, 8690 .114 

FIRST SUBSECTION. VEGETATIVE ORGANS. 

Their general Character, $$91 94 .1 17 

FIRST CHAPTER. 

THE ORGANS OF NUTRITION.' 

1. The Intestinal Canal and its Appendages, 95 114 . 1 19 

II. The Fatty Substance, 115 .151 

I IF. The Blood-vessels, 116121 . 153 

IV. Tlip Organs of Respiration, 122 130 



TABLE OF CONTENTS 1\ 

SECOND CHAPTER. 

THE ORGANS OP GENERATION. 

PAGE 

Their general Character, 131 134 . . .181 

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

II. Male ditto, 146152 . . 200 

III. Development of the Sexual Organs during the Metamorphosis, 

153 . . ... 220 

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

SECOND SUBSECTION. THE ANIMAL ORGANS. 

Their general Character, 155157 . . . 224 

THIRD CHAPTER. 

THE ORGANS OF MOTION. 

I. Of the Horny Skeleton, 159168 . . 226 

II. The Muscular System, 169181 . . 247 

FOURTH CHAPTER. 

THE ORGANS OP SENSATION. 

Their general Division and Character, 182 . . . 269 

I. The Brain, 183 185 . .272 

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

III. The Sympathic System, 189 191 . . 2*6 
IV. The Organs of the Senses, 192198 . 289 



THIRD SECTION. PHYSIOLOGY. 

Its idea and subdivision, 199200 . . . 302 

FIRST SUBSECTION. SOMATIC PHYSIOLOGY. 

Its idea, 201 . 304 



TABLE OF CONTENTS 

FIRST CHAPTER. 

PAGE 

Of Generation, 202213 . . . 306 

SECOND CHAPTER. 

Of Nutrition. 

Its general character and kinds, 2J4 216 . . 344 

I. Digestion, 217225 . . . 347 

II. Respiration, 226236 . . 384 

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

THIRD CHAPTER. 

The Metamorphoses, 244260 . 414 

FOURTH CHAPTER. 

The Muscular Motion, 261267 . . .445 

FIFTH CHAPTER. 

The Sounds emitted by Insects, 268271 . 466 

SIXTH CHAPTER. 

Of Sensation and the Senses, 272 278 . . 474 

SEVENTH CHAPTER. 

The Luminousness of Insects, 279282 . . . 490 

SECOND SUBSECTION. PSYCHOLOGICAL PHYSIOLOGY. 

The Nature and Object of Instinct, 283286 . . 498 

EIGHTH CHAPTER. 

THEIR SELF-PRESERVATION. 

I. Means of Defence, 288 . . 504 

II. Instinct of Nutrition, 290 . 511 



TABLE OF CONTENTS. XI 

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, 301306 . 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 CH.4PTER. 

Relation to the Antediluvian World, 314317 574 



FOURTH SECTION. TAXONOMY. 



FIRST CHAPTER. 



General ideas Nature of Artificial and Natural Divisions, 318321 582 

I. Idea of Species, 322324 . . 588 

II. Idea of a Genus, 325331 . 590 

III. Idea of the Higher Groups, 332336 . 594 



Xll TABLE OF CONTENTS. 

SECOND CHAPTER. 

HISTORY OP THE PRINCIPAL SYSTEMS. 

PACK 

Earliest essays, Aristotle, 337 . 597 

More recent ones, 338343 . 598 

Zootomical systems, 344349 . 608 

Physiological systems, 350 352 . 617 

THIRD CHAPTER. 

Nomenclature, 353363 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 

B 



2 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 similar 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 ORISMOLOGY, 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 has introduced the term ORISMOLOGY in lieu of the hybrid compound 
TBIIMINOLOGY, but which being derived from 'opiff^os (terminus, dejiitltio) should be 
written Horismology. But as it is not unusual to reject the spiritus asper, we have 
retained his orthography. 



INTRODUCTION. 3 

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 denned 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, Bitgs,$c.) 

b. having a masticatory mouth. 

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

B2 



4 INTRODUCTION. 

2. ORDER. ORTHOPTERA. (Locusts, Grasshoppers, ffc.) 

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

3. ORDER. DICTYOPTERA. (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. (Ffe.) 

b. Insects with four large wings, covered wholly, or partially, 

with broad scales. 

5. ORDER. LEPIDOPTERA (Butterflies, Moths.) 

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

dibles and palpi. 

a. Four equal wings, with reticulated nervures. 

6. ORDER NEUROPTERA. (Dragon Flies, $c.) 

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

7. ORDER. HYMENOPTERA. (Sees, Wasps, Ichneumons, $c.) 

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

case. 

8. ORDER. COLEOP-TERA. (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 

APTEKA. 



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 



I 

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 (e.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 
toother 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. (Kirlys Exterior Anatomy.) 



OF.NEK.U, I'lUNCIPLKS. 



FIRST CHAPTER. 



GENERAL PRINCIPLES. 




ALTHOUGH we here, at once, declare ourselves opposed loan unne- 
cessary multiplication of orisaiological 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 npply 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 ns 
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 (collum), 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, ami notwithstanding its toleration l>\ the great masters of the science. 



8 



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 *. 

11. 

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 (pinnae). 

* 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 collare, 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 clypeiis. 

| It consequently appears preferable to us to call the first segment of the thorax the 
prothorax, rather than collare, exclusive of the greater precision and comprchensibility ot 
llu- first term. 



I. 

GENERAL PRINCIPLES. 9 

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 em 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 ; 
natatofius, 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, ex, or in, 
in Latin words : for ex. apterus, without wings ; escutellatus, without 
a scutellum ; iner.mis, 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. squamosissimus, densely covered with scales ; rugo- 
sissimus, very uneven ; distincte-punctalus , 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 ; subpunctalus, slightly punctured ; snbstriatus, 
slightly striated; hirsutiuscuhis, somewhat hairy. 



10 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 ; obovafus 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. puuctatus indicates 
being covered with punctures ; striding, 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 ; punctalo-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, Avhich, 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, \ve meet with difficulties in the selection of the 
exactly appropriate word, so that peculiar orismological terms are 
requisite for their correct definition. 



GENERAL OlllSMOLOGY. 1 1 



SECOND CHAPTER. 

GENERAL OlllSMOLOGY. 




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. 

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

CONTOUR (peripheria), a portion whereof is the MARGIN (niargo). 
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. 



12 GENERAL ORISMOLOGY. 

SUPERIOR SURFACE (superficies externa), the INFERIOR SURFACE 
(sup. internd), 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. 13 

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 (triangulare), when the margins meet in three angles. 

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

QUADRANGULAR (quadrangulare) , when two of the nuij^ms arc 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 (spattdatuin), 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 antennae of many 
Tachina and other Diptera). 

LOZENGED (rhomboidaE), a quadrangular figure, with two opposite 
angles acute and two obtuse. 

19. 
forms of Bodies. 

SPHERICAL (globosum, sphcericuin), a round body, having all its 
diameters equal. 

HEMISPHERICAL (semiglobosum, hemispheericujri), 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. 



14 GENERA f, OKISMOLOGY. 

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 (incrassatuni), 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 (pyrijbrme), a similar shape, but with this difference, 
that its longitudinal section is spatulate. 

FUNNEL-SHAPED (infundibulifbrme), resembling the last in exterior 
form, but scooped out at its apical margin. 

FORNICATE (fornicatum), 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 (triquelrum), four sided (telragomim), &c. 

PRISMATIC (prismalicum), 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 (cuneaium), 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 (arcuatu,?) 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 (crenalus), 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 (cilialus), when it is occupied with short stiff hairs. 

LOBATE (lob at us), 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. 15 

TKNTACULATE (tenlaculatus), when soft tensile excrescences are 
found upon the margin (Caniharis, Malachius). 

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

MAKGINATE (marginal us), is when the sharp edge is margined, and 
surrounds the surface with a narrow border. 

DEFLEXED (defle,rus~), when this sharp edge is bent downwards. 

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

INCRASSATE (incrassaius), 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 (angustalum), or COARCTATE (coar datum), 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 (truncalum), when a part is limited at the end by a 
straight line or surface. 

ROUNDED (rotundatum}, when the end takes the form of a segment 
of a circle. 

PREMORSE (pr&morsHm*), when the end appears bitten off or splintery. 

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

RETUSE (retustim), when the terminal margin has an obtuse im- 
pression. 

OBTUSE (obtusiim}, 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 (mucronatum) , when from an obtuse end a fine point 
suddenly proceeds. 

CUSPIDATE (cuspidatuni), when this pointed process is very much 
extended, becoming almost setiform. 



r 

l(j 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. 

CORIACEUS (coriacenm), 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 (solidurri), is a substance consisting of one mass, with no vacant 
interstices. 

POROUS (porosuni), 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 whole 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. 17 

24. 

Differences of Surface. 

SMOOTH (lave), a surface without either impressions or elevations. 

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

SHINING (nilidum, 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 (scabnmi), a surface covered with small and slight 
elevations. 

ROUGH (asperurri), when these elevations are more perceptible. 

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

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

GRANULATED (granulatuni), when small roundish elevations are 
placed in rows ; MURICATE (muricalnm), when dispersed elevations rise 
in sharp points; ECHINATE (echinatum) , when they rise higher, and 
are thinner ; CATENULATED (catenulatum), when longitudinal eleva- 
tions are connected like the links of a chain, and are placed in rows ; 
INTRICATE (intricatum), when the elevations and depressions are placed 
without any regularity, but close to each other ; PAPILLULATE (papil- 
hilatuin), when the dispersed elevations or depressions have a smaller 
elevation in their centre. 

LINEATE (lineatum), when there are fine longitudinal elevated lines ; 
COSTATE (coslatum), 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 

c 



18 GENERAL ORISMOLOGY. 

elevated ridges ; CANALICULATE (canaHculatinii), is a surface, which has 
in its centre a broad, but not very deep longitudinal furrows ; EXARATE 
(e.raratum), 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 (varioloruin), when larger depressions are iso- 
lated, and resemble the maiks of the small-pox; FOVEOLATE (foveo- 
lalum), or SCROBICULATE (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 (favosuni), when these depressions 
stand close together, so that the surface resembles a honey-comb ; 
ENGRAVED (ejcsculptuvi), when a variety of irregular longitudinal 
depressions cover the surface; VERMICULATE (vermicrilatum}, when 
the depressions are longitudinal and tortuous, like a Avorm-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 (convexinn), when a surface 'rises gradually to its centre, 
which becomes thus the highest of the whole. 

CONCAVB (coticavum), 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 (aculeatum'), with slender pointed processes ; SPINOSE 
(spinosu-ni), covered with solitary, thicker, and frequently bowed pro- 
cesses. 

UNARMED (mut'icum, inertne), when no such processes exist. The 
first word is generally used when terminal processes are wanting, where 
they are usually present. 



()Kisi\roLo<;-\ , 19 



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 Qz7z) 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, kolosericeum) , 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 (ciliatum), 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- 
iatum\ 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; POLINOSE 
( polinosurnj, this dust, when yellow, like the pollen of flowers ; PUL- 
VERULENT (pulverulenittm), RORULENT (rorulentum), express very 
similar, scarcely precisely distinguishable qualities ; LUTOSE (lutosuni), 
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 
the sppric<i of the prncni Arida, Melcnt rariolosus. 

c2 



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

PENCILLATE (pencillatum) , when long flexible hair is placed upon 
a thin stalk. 

FIMBRIATE (Jlmbriatum), when a part is fringed with hair of 
irregular length. 

JUBATE (jubattnri), 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 where 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, Ilistoire Naturelle des Crust, et des Insectes. Paris, an. XII. Vol. i. 
p. 331, &c. 



GENERAL ORISMOLOGY. 21 

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. 



22 GENERAL ORISMOLOGY. 

29. 

WHITE (albus), a pure plain white. 
NIVEOUS (niveus), the purest, dazzling white of snow. 
LACTEOUS (lactens), 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 (anthracinus), 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 (caslaneus), 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 broAvn, the colour of soot. 

UMBER (umbrinus), a bright dark brown,' with some yellow 

FULVOUS (fulvus), a light brown, with much yellow. 

33. 

RED (ruler'), the usual red ; the colour of burnt tiles. 
MINIATOUS (miniatus), the colour of red lead. 
LATEIUCEOUS (lalcricius), the yellow-red of yellowish bricks. 



GENERAL ORISMOLOGY. 23 

SANGUINEOUS (sanguineus), a deep red, with a dash of blue, the 
colour of fresli blood. 

PURPLE (purpureus or jjuniceus), a bright red, with a violet tint. 

34. 

BLUE (cyaneus), pure dark blue of Indigo. 

AZURE (azureus), a clear brilliant blue, viz. wings of Lycaena. 

SKY-BLUE (cdBtruleus) a pale blue, like the colour of the sky. 

VIOLET (violaceus~), a blue, with a reddish tint. 

PRUINOSE (pruiniis, pruinosus}, a reddish blue, with a whitish 
covering, like the bloom of ripe plums. 

GLAUCOUS (glauciis}, a bright blue, with a strong admixture of 
white, inclining to grey. 

C^ESIOUS (ccesius,') a greenish, grey, sordid blue. 

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

35. 

YELLOW (Jlavus}, most beautiful, and purest in the colour of 
sulphur, thence sulphureous (sulphureus) . 

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

LUTEOUS (luteus), 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 (tcstaceus), a dull, yellow brown. 

36. 

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

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

PRASINOUS (prasinus'), a light green, inclining- to yellow. 

OLIVACEOUS (olivacens^, a green, Avith an admixture of brown. 

YELLOW-GREEN (faivo-vircns'), a bright green, with the yellow 
predominant. 



24 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 opalissans), the prismatic reflection of the 
opal. 

MARGARITACEOUS (marg'aritaeeus\ reflecting the prismatic colours 
like mother of pearl. 

CRYSTALLINE (crystallinus), the pure transparency of crystal. 

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

SMARAGDINE (stnaragdinus), 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. 

./ENEOUS (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 (pustuld), a point of larger circumference. 

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

GUTTA (gulla), is a light spot upon a light ground, viz. white upon 
yellow. 



GENERAL ORISMOLOGY. 25 

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

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

LINE (linea), a very slight, generally straight, but also sometimes 
gently bent, differently coloured stripe. 

VITTA (viita), a broad longitudinal stripe. 

STRIGA (striga), a transverse band. 

FASCIA (fascia), a broad transverse band. 

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

LUNULET (lunulct), 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 Elytra vittala, &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. 

NEBULOSE (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 (Jenestratus), 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 (imdulatus), when the markings are waved either 
longitudinally or transversely. 

UNICOLOR (wm'co/or), 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. 



26 



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 
s pecies 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 folloAving 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. TR. 



GENERAL OKISMOLOGY. 27 

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-half 
broader, dimidio latins, &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, quadrtiplo-minus ; four times as large, quadruplo-majus. 
Quincuplex and sexluplex, are also, but very seldom, used. 

42. 

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



* Illigcr's Magazine, vi, 229. 

t Neuc. Schreftcn der Hallis. nuturf. 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 (adnatuiri) are those parts 
which form an immediate continuation of the base upon which they 
repose, and are besides immoveable. ARTICULATE (arliculalum), 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 then- 
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 gynglimous 
(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 (anticuiii), lying near the head. 

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

SUPERIOR (suprci), placed upon the back. 

INFERIOR (infra), attached to the ventral portion of the body. 

BOTH SIDES (utrinque), 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 (uxillares), are those which spring from the point of 
union of two others. 



GENERAL OK ISMOLOG Y. 29 

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 (involutes), are also thus 
distinguished, but they indicate a greater degree of it an absolute 
rolling up. 

COMPLICATED (complicates), is a part laid longitudinally in folds ; 
REPLICATE (replicates), 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 (reclus) ; 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 ORISMOLOGY. 31 

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 (ovafe) ; 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 Lepidoptera. 

SEMIGLOBOSE (semiglobosum), likewise in several Lepidoplera ; for 
example, in Harpy a vinula (pi. i. f. !) 

CONIC (conicuiri) also among Lepidoptera, as in Pontia Brassicee 

(pl.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 (cucurbitaceum) ; PEAR-SHAPED (pyriforme) ; BARREL- 
SHAPED (pi. i. f. 5). 

Many eggs are placed upon long, straight (Hemerobius perla, pi. i. 
f. 14), or shorter, bent (Ophion luteus, pi. i. f. 16), footstalks, and are 
thence called PETIOLATED (ova petiolata). Others have atone 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 alala) ; 



32 PARTIAL ORISMOLOGY, 

others with short ribs extending from one pole to the other (ova costctta, 
pi. i. f. 5)j others with 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 reliculata), Hipparchia Hyperanfhus (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. Brassicte). 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 baccarum), or banded 
(Gastr. querci folia, 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. pilnla- 
ritts) ; 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 (ovafavosa, for ex. Apis, Vespa, Pelopceus). All these 
eggs adhere by a peculiar gummy secretion, and are thence called ova 

* Lin. Tr. vii. 3-1. 



THE LARVA. ;J3 

gummoxa ; but such eggs as lie dispersed in any substance, as, for ex. 
the eggs of the house fiy (Mitsca domestica),in dung, are called naked 
(ova 7iuda). 

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. THK 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. 
incomplete.), 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. 

D 



34 PARTIAL ORISMOLOGY. 

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

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

OBTECTED (in. obtecia], 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. coarctato} 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 Stratiomys ; 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 knomv species, as the larvae are invariably smaller than the 



THE LARVA. 35 

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 larva; 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 (PI. II. f. 1) ; in others the head is clearly distinguished, 
but the feet are wanting (PI. 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 LARVAE (PI. 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 PROLKGS, 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 (capiit) 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 Ratzehurg*, 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. 43, 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 larvae of the males of the aculeate Hymenoptera 
will necessarily have an additional segment. Ratzeburg 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. Ca-s. Leop. Carol. Nat. Curios, t. VIII., pi. i. p. 145. 

D 2 



30 PARTIAL OKISMOLOGY. 

of the head occurs only in the maggots, which are destitute of all the 
organs observable in the heads of caterpillars, such as antenme, 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 Ligusl.ri, Smerinthus Popu/i, and many others); sometimes 
each half is produced at the vertex into a pyramidal process (Apatura 
Iris, PI. 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 
Mat, longitudinally quadrate ( sometimes taking the shape of a segment 
of a circle) corneous upper-lip, or LABRUM (labrum, PI. II. f. 13, ) ; 
the equally strong corneous, horizontally-moving- upper-jaws, or MANDI- 
BLES (mandiiiulas, PI. II. f. 13, A, b) ; the weaker, but very similar, 
under- jaws, or M AXILLAE (rnaxillce, 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 (antenna, f, f) are placed near the mouth, at the 
base of the mandibles and maxillse. 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. 



HIE LARVA. 37 

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 (fusulua, 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 Dictyoloptera, 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, Phn/gaiiea}, 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 (pcdes) of larvae take a different form, according to their 
position 



38 PARTIAL QRISMOLOGY. 

The true LEGS, THORACIC LEGS (pedes merely, or pedes veri, 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 (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 larvse of the Coleoptera and 
Diclyotoptera, 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 larvse from these differences, 
which we shall here introduce for the purpose of giving a general view 
of them. 

I. Larvse without feet. 

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



THE LARVA. 39 

2. With a corneous head of determinate shape, (many Coleo- 
ptera, the Rhynchopkora, many Hymenoplera, Culicina, 
Tipularid), PI. II. f. 3. 
II . Larvae with feet. 

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

a. Joints short and conical (Elaterodea, Cerambycina), 

PI. II. f. 4. 

b. Joints longer (Cicindelacea, Carabodea, Hydrocan- 

tharides, Brachyptera, Lamellicornia , Cuccinellacea, 
Neuroptera), PL II. f. 6. 

2. Prolegs only (Tipttlaria, and other Diptera, (Ecophora), 

PI. II. f. 2. 

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

a. Without claws (Tenthredonodea'), PI. II. f. 5 and '/ 

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 : but, 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 hymenopterous 
Apods Culicidce, some Tipnlarics, &c. amongst the Diptera). 

ii. With a membranaceous head of indeterminate shape (Muscidce, Syrphida, 
and other Diptera). 

II. Larvae with legs. 

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

Coleoptera). 

\. Joints short and conical (Elater, Cerambycidce, Sic.). 
2. Joints long and subfiliform (Staphylinus, Coccinella, Cicindela, &c.). 
ii. Prolegs only (many Tipularite, and some subcutaneous lepidopterous larvae, 

&c.). 
iii. Both legs and prolegs (Lepidoptera, Serrifera, and some Coleoptera). 

1. Without claws (Serrifera, &c.). 

2. With claws (Lepidoptera, &c.). TR. 



40 PARTIAL ORISMOLOGY. 

Rajella*J, 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, PL II. fj. 

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, PL II. f. 5. 

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

The majority of caterpillars, namely all the hawk moths (Sphing- 
odea), butterflies (Papilionacea), bombyces (Bombycodea), 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 
geometrifurm.es), PL 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), Larva geometrce, PL II. f. 11. 

The majority of the Phalcenodea. 

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

Naturfoi-sch. St. IV. p. 37, &r. 

\- This is a similar arrangement to that of Reaumur, in his second Memoir in the first 
volume, nol v somewhat modified and enlarged. TR. 



THE LARVA. 41 

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 (spiraciila, 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, throughout which the trachete, or AIR TUBES, are 
distributed, and which thus supply the function of gills, and may, 
therefore, be very properly called gill plates (branchiae, aer'iductus, 
of Kirby and Spence). They are distinctly observable in the larvae 
of many May-flies (Ephemera 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 Slrntiomys and gnats 
(Culex), 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 Dy(iscux); in others 
(Erisialifi, 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. 



42 PARTIAL OR1SMOLOGY. 



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 larva? 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 SPJNOSE cater- 
pillars (larvae acnleatce), 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 polych/oros), 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, larvae cornutcK), of which it is fabled that it supplies 
the place of a poisonous and severely wounding sting. A few have, 
instead of this, a furcate process (Harpya, Ochs, Centra'), 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 (Larvae furciferai). But, 
with respect to their powers of injury, greater attention is claimed by 
the HIRSUTE CATERPILLARS (Larvce ursin(e), 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 larvae, 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 PUI'A. 43 

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. Pupa? without alary appendages, which, according to the Fabrician 
definition of the metamorphoses, must be called COMPLETE FUPJE, but 
which, according to us, are necessarily incomplete pupae. To these 
belong the lice (Pediculus"), the bed bugs (Cimex lectitlarius), many 
species of the genus Phasma *, and some other wingless Hemiptera 
and Ortkoptera. 

2. Pupae with the rudiments of wings, according to the former 
definition, Semi -complete Piipce, but by us they are called Sub- 
incomplete. These comprise all the pupee of the winged genera of the 
Orders, Hemiptera, Dictyoto/ilera, and Orlhop'era. 

Lamarck calls nymphce 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- 

O ' 

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. R. Gray's valuable " Synopsis 
of the Species of Insects belonging to the family of Phasmidee," 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. Ta. 



44 PARTIAL ORISMOLOGY. 

I. Pupae which freely lie, hang, or are in any way fastened or 
attached in their particular element, NAKED PUP.E (Pupce mida}. 
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 PUP-ffi: (Pupce foHiculatce} , which case is called COCOON 
(incunabidum, 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 (Pupce oblecfte, coarctatce}, are 
those which are inclosed in a firm, egg-shaped, corneus 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 (Syrpkodea, 
(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 folUcidata 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 PUP^; (pupce.lartiaife'), 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 pupse (pupee exarattf}, are such in which 
the limbs of the perfect insect are observed to lie free, although still 
closely attached to the body fPl.II. f. 24). These Lamarck calls mumia, 
and particularly mumia coarctala (Coleoptern, Hymenopiera), whilst 
the pupa? of the Phryganea, which, in the last stage of their pupa 
existence possess some degree of motion, he calls mumia; pseudo- 
nymph(e. 

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 (/jw/jfl adhcerens), 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 (Pontia Cratcegi). An incased pupa, 
whose cocoon remains partially open (Sdturn'xi, Pkryganea),is usually 
called a GUARDED pup;i ' iipn custodiata}. 



THE PUPA. 45 

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 (thecct) 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 (optlialtnotheca), the MOUTH-CASE (stoma- 
totliecci), 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 (podotheca), 
inclined towards each other at acute angles ; very near to them, but 
directed outwards towards the back, the either long, pointed, or shorter 
thicker ANTENNAE CASES (Ceratofhec&y*. Next to the head-case 
follows the TRUNK-CASE (thorcicotlieca, cytoiheca of Kirby and 
Spence), which is covered below by the WING-CASES (pterothecte'), 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 (mesothoracotheca) , 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 ABDOMEM-CASE (gasterothecd), 
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, 
spiraculce) 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 CeraiheccB, according to Kirby and Spence. 



46 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 Harpy a 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 (Sirex, 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. 

02. 

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. piceits), 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 (Cule#), 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) 

* Burrueister has evidently made a mistake here ; for the pupa of Pygera bucephala 
is perfectly smooth The pupa of Leucom'a Salicis would have been a better example. TR. 
t Memoirs, 76, pi. 14, fig. 8. 



THE PUPA. 47 

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

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. angularex); the rest, in contradistinction, are styled CONICAL 
(/>. conicce). 

64. 

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

All pupa? 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, aurelia, 
which names have been applied in general, but chiefly by early writers, 
to the pupae of all the butterflies. 



48 PARTIAL ORISMOLOGY. 

/ 

IV. THE INSECT IN ITS PERFECT STATE (Imago}. 

65. 

An insect, when it quits its pupa case, is called PERFECT (imago, 
insectum dedaratum, 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 
"Evrofj.a, which word is derived from ivre^veiv, 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. 



TIIK HEAD. 49 

I. THE HEAD (Capvt). 
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 analagous 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, Straust), PL HI- 
f. 11, A. It is limited in front by the CLYPEUS (ch/peus), called LOWER 
FACE (Jiypostoma, 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 



* 111 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. 

j- Considerations Generales sur rAnatornie comparee des Animaux articules. Par 
Here. Straus-Diirckheim. Paris, 1828. 4to. av. 10 fig. (p. 52, &c). 

E 



50 PARTIAL ORISMOLOGY. 

the eyes (PI. III. f. }], c). Kirby and Spence call tliis 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 to be flattened above (PI. 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 which 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 (fades) 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 (mystaai), and is found chiefly among the 
Diptera 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 (Carabus], 
this part is sloped, and its anterior raised margin, 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 capitate). Straus correctly considers this swelling as 
belonging to the basal part, and which he calls prebasal part (pre- 
basilaire). 



THE HEAD. 51 

The sides of the head, from the eyes downwards to the mouth, are 
called CHEEKS (gencp, 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 
(tempora, PI. III. f. 13, F). 

The back of the head around the commencement of the neck is the 
OCCIPUT (occiput, PL III. f. 12 14, G). In many instances, chiefly 
among the Coleoptera and Ortlioptera, 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 nock 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 \\ieColeoptera 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 OP THE MOUTH, the ANTENNA, and the EYES. 

The 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 



52 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. 
mordent ia, s. libera) from the SUCKING ones (instr. cib. suctorict) ; 
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 Hymenopterci) 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 {. 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 APFENDICLE (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. + Terminologie, p. 220. 

Burmeister says it is the genus Hylaus, 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. 53 

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, branche 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 dorsals 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 palpiftre, 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 
(lolus maxillae, 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 extemus). 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 Illiger * 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 

O 

(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, 

* Sec Kaefer Preusscns, 1 Vorrcdc, p. xxxvi. note 15. 



54 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, PI. 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 labiates^) 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 (PL IV. f. 5), as in the Orthoptera and Xenroptera; in other cases 
it is divided, and very closely connected with that organ (Coleoptera). 
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 muxillares, PI. 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, PI. 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 tbey 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, 
PI. III. f. 17, 5, and PI. 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 (zalca) of the Orthoptera^ 



THE HEAD. 55 



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 (promincns, 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 
(perpendicukire) 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 liberuni) 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 (retractuin), when it is concealed as far as the brow 
within the thorax (Bupreslis). 

CONCEALED (abscondituni), 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 (Hi&ter). 

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

From its anterior margin it is distinguished into CLYPEATE HEAD 
(c. clypeatum, PI. IV. f. 6), when tolerably flat, and the margin of the 
clypeus and the front are produced into a broad border ( Copris, Ontho- 
pliagus, Ateuchus} ; TURRETED (c. turritum, PI. IV. f. 7)> when it is 
produced anteriorly and above into a pyramidal point (Truxafcs). 
We have already mentioned HORNED (c. cornulum) and ROSTRATE 
(c. rostraium) heads. A head furnished with swollen cheeks is called 
BUCCATE (c. buccatum, PL 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, 



56 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, PL 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 incucillosus. 
They call TEETH {denies) the pointed processes on the inner side, 
and very skilfully distinguish the superior, compressed, sharp edge as 
CUTTING TEETH (denies incisivi, the same figure, a) ; or they call 
them CANINE TEETH (denies laniarii, s. can in i), when they are very- 
sharp and conical. GRINDING TEETH (denies molares') are the inferior 
thicker teeth, provided with a broad grinding surface (Melolonthd). 
The MOLA, or grinding surface (mola, the same tig. b), 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 Bombi, Melolontha, &c.). 
In the Coleoptera, this molar tooth is clothed laterally with short stiff 
hair, which Straus calls the BRUSH (brosse). 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. corneas) ; in other 
instances they are membranaceous (m. membranacete), as in the Lamelli- 
cornia coprophaga: in these also they have in general a hooked shape. 
In the Hemiptera, and many Dlptera, they are SETACEOUS (m. setacece, 
xetce 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. 57 

teeth upon the inner margin of the maxillse, 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. penicillatee, 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. setosce, s. setce 
rostri infer lores) in the Hemiptera and many Diptera ; in some of the 
latter (Tabanica) also LANCEOLATE (max. lanceolate?}. They are 
UNGUICULATE (TO. tinguiculatfe), 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 (Clcindelacea). 

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 (Libellulhia, 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 



58 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 j in the Orthop- 
tera, the former five the latter three ; in the Hymenopteret, 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 jilifurmes, 
PI. IV. f. 12, a) ; that is to say, such which have all their joints of an 
equal cylindrical shape ; MONILIFORM (p. moniliformes), when the joints 
are globose, like beads ; SETACEOUS (p. setace.'i), 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 (Alractocerus}. 

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. cuneif onnes}, when the last joint has the form 
of a wedge, which is attached by its sharp end to the preceding joint 
((.'arabus, Calo oma, Cychrus, PI. III. f. 16, t). 



THE HEAD. 59 

TURGID {p. turgidi, PI. IV. f. 22), when the last joint has the 
appearance of a distended bladder (G ryllotalpa). 

EXCAVATED ( p. excarati, PI. 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. truncuti), when the last joint appears to terminate 
abruptly (Prionus). 

DIVIDED (p.fasi), when the last joint is divided longitudinally. 

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

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

ELONGATE (p. elongati), are those palpi Avhich 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 antennas (Hydrophilus). 

UNEQUAL (p. intequales), when single joints take a different form 
(Banchus, Ichneumon, PI. 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 (Jiaustellum), 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 napper-shaped suctorial surface. Upon the 



60 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 (PI. 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 
Amentum'). 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, PI. 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 (PI. V. f. 1 7- 
c, c). The setae themselves are concealed by the superior, broader, 
somewhat convex, upper lip (PI. 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 MAXILL/E (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, PI. 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. 61 

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, setce super lores et inferior es ; the central tongue, ligula. 

The SPIRAL TONGUE (lingua spiraUs, 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, l>, and fig. 17)- They are both covered by the 
large forward ly-bent labial palpi (PL 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,); 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 eesophagus, 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 
FEELEK (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 (Puhx), 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 



62 PARTIAL ORISMOLOGY. 

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

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, PL III. f. 11, 12, 13, a. a., PI. V. f. 15, A., 
PI. VI, 3 and 8, A. A.) also called COMPOUND EYES (oculi composite), 
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 (ocuh 
distantes), but they frequently join closely together in male insects 
(oculi approximati, for ex., in the dragon flies, the male Syrphi, 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. Ent. p. six, 4. 



THE HEAD. 63 

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 Tetraopes, 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 ANTENNAE (Antennae). 

72- 

The ANTENNJE 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 (Plulop- 
terus, 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-Dtirckheim, 
denies their being eyes, although he does not dispute the existence of the points, page 58. 



PARTIAL ORISMOLOGY. 

1. Situation of the Antenna 1 . 

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

PREOCULAR (ant. prceoculares}, are such as are inserted close to the 
front of the eyes (Carabus, PI. 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-oculares), when inserted beneath the eyes. 

When they are placed, as is usual, upon the upper part of the head, 
they are called SUPERIOR (a.superiores); but when beneath, INFERIOR 
(a. inferiores). 

When their basal joints are inserted very closely together, they are 
called APPROXIMATE (a. 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). 

VERY LONG (longissimce'), when they are considerably longer than 
the body (Lamia cedilis), Fab.). 

SHORT (breves'), when about the length of the head. 

SHORTER (breviores), when they are longer than the head, but 
shorter than the body. 

VERY SHORT (jbrevissim.ce}, 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. 



n. Equal Antenna. 

SETACEOUS (setacea, PL VII. f. 1), are such which very gradually 
decrease, becoming pointed at the apex (Locust a, Fab.). 

SETIFORM (setiformes, PI. 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, PI. VII. f. 3), by 
the latter being shorter, thicker, and slightly bent (Leptis"). 

FILIFORM {jiliformes, PI. 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 h when the joincs are com- 
pressed, and have a sharp edge on each side (Truxalis}. 

FALCIFORM (falciform^, PL VII. f. 7), when arched like a sickle. 

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

SERRATE (serrata, PL VII. f. 9), when the joints are triangular, 
and are so arranged that the prominent angle is placed anteriorly, and 
inclines downwards (Elate)-}. BISERRATE (biserratai), 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 (imbricate, 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 (pectinate, PL VII. f. 11), when the joints have long 
processes on one side, like the teeth of a comb. BIPECTINATE 
(bipectinatce), when such a process issues from each side of the joint 
(Lopkyrus} ; or DOUBLY PECTINATED (duplicato-pectinatce, PL VII. 
f. 12), when there are two processes on each side of the joints 
(Ctcnophora). CIRRATE (cirratce, 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 
(distichtz'), 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 ( fiabellatce, PL VII. f. 14), 

F 



66 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 (biflabdlalce) , when both sides of the joints send forth such 
processes. 

BRANCHED (ramoscp}, 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 (furcates, PI. VII. f. 16), is when throughout its whole 
length it is separated into two branches or prongs (Schizocerus, 
Lat.). 

b. Unequal Antennae. 

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 (fractal), or GENICU- 
LATE (geniculatte, PI. VII. f. 17) ; and the long joint is distinguished 
as the SCAPE (scapus, the same, a~), and the following as the BRANCH 
(flagelhim, the same, b). 

The branch of such geniculated antennae is frequently merely cylin- 
drical or filiform (Apiuria, 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 (capiiatce), 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 composition, PI. VII. f. 19, 
Necrophorus). PERFOLIATE (cap. perfolialum) , when the joints of 
the knob slightly stand off from each other all round (Hydrophilus, 



THE HEAD. 67 

PL VII. f. 20) ; LAMELLATE (cap. lamelhitmn), when the joints of 
the knob extend on one side into broad leaves (PI. VII. f. 21, 
Melolontlia) ; TUNICATE (cap. tunicalum), when each successive 
joint is buried in the preceding funnel-shaped one (PL VIII. f. 1, 
Lethrus} ; INFLATED (cap. iiiflatum), when the knob has the form of 
a broad bladder (PL VIII. f. 2, Paussns) ; SPLIT (cap. jissuni), when 
the joints upon one side are divided as by incisures (PL VIII. f. 3, 
Lucaims). 

HOOKED (imcinatce], when the last joint bends back upon the 
preceding (PL VIII. f. 4, the male of Odynerus}. 

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

ANGUSTATE (angustatte), on the contrary, when the middle joints 
are thinner than at the beginning or the end (PL VIII. f. 6, Asilus). 

SETIGEROUS (seligerte), are such whose terminal joint has upon its 
upper side a fine BRISTLE (seta). The bristle is either SIMPLE (sim- 
plex, PL VIII. f. 7), or PLUMOSE (plumosa, PL VIII. f. 8, Volucdla), 
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 (rnucronatts), are those whose last thick joint suddenly 
terminates in a sharp point (PL VIII. f. 18, Empis). 

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

IRREGULAR (irregulares), lastly, are all such antennae, all or several 
of the joints of which aue dissimilar in form to eacli other (PL VIII. 
f. 22, Cerocoma ; f. 30, Agaon). 

4. Number of the Joints, 

Antennas which consist of but ONE joint are called EXARTICULATE 
(exarticulat<z) ; others, which have but few joints, are named from 
their number, as biarticulate, with TWO ; inarticulate, with THREE 
joints, &c. But those whose joints are very numerous are called 
MULTIARTICULATE (miilliarticiila/<v). 

F2 



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 pnpipara, have exarticulate, or one-jointed 
antennae ; the majority of the rest of the Diptera, such as the true 
flies (Muscaria}, and Syr phi, 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 (PL 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 POUR 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. (Tetligonia, Fab.) 
which has FIVE. The genera Asilus, Dioctria, Dasypogon, Hilara, 
Empis, and Sargus, among the Diptera, have FIVE joints (PI. VIII. 
f. 7 and 18). It is the same in the apterous flea (Pitlex), the lice 
(Pediculi), and the genus Philopterus, among the equally apterous 
parasitic skin-destroyers (Dictyotoptera mattopkaga). Two other 
genera of this family, viz. Liotheitm 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,Me\g. (Hep- 
tatoma, Latr.), and Nematocera, Meig. (Hexatoma, Lat.). From SEVEN 
to EiGHT-jointed antenme are found in other Diptera, in the genera 
Stratiomys, Oxycera, Tabamts, 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, Ori/ctes ; NINE in Copris, OniticeHus, Ateuchus, Apho- 
dius, Geniates, Kirby; Plian&us, Leach (Lonchoplwms, Germar), and 
many of their affinities; EIGHT, Dorcatoma and Calandra; FIVE, 
Platypus and Claviger ; TWO, Paussus. IMore 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 ; Rli. 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. G9 

and the male THIRTEEN joints. The Diptera, with ..uform and multi- 
articulate antennae, possess a vai-ying number; BiUo, Latr. (Hirtcea, 
Fab.), lias NINE ; ELEVEN, Diloplms, Scatopse, and Simnlia ; the Tipu- 
laria, from THIRTEEN to SEVENTEEN; and all theTipularicefiwgivorce 
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 Forjicula, 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. obconici). Bell- 
shaped, or CAMPANULATE (. campanulati), are those which are con- 
cave at their broadest end (PI. VII. f. 10). TORULOSE (a. tornlosi), 
such as have greater or smaller tumours upon them. Those which 
are produced laterally into lobes or processes (art. lobati, s. producl'i), 
have been previously mentioned. Moon-shaped, or LUNATE joints 
(art. lunati), are found in the male individuals of the genera Ncphro- 
toma andEucera (PL 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 Antennae. 

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

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



70 PARTIAL ORISMOLOGY. 

BEARDED (barbatee), when the short and thickly-set hair covers the 
antennae completely upon one side. 

FASCICULATE (fasciculate}, 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 antennas (many species of Lamia, PL VIII. f. 26). 

PLUMOSE (plumosee), 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. 71 



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, stetkidium*). 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 capitt, truncus, abdomen. 
and artus. That this subdivision is inadmissible, is sufficiently ex- 
plained at the above-cited place. How this, his iruncus, 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, 
sterna \. 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 ( 11). 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, Bouclie, and others, is less applicable than thorax, because 
it is borrowed from the Greek (derived from o-<rj9-of), 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. 

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

; Philos. Entoni., p. 22, 7. 



72 PARTIAL ORISMOLOGY. 

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 (truncus), which comprises the neck (collwm), the breast 
(pecfus), the abdomen, the scutelluni, and the wing-cases (elytra). 

The neck (collum, our prothorcui) is divided into the upper side 
(thorax), and the under side (juguhim). In the centre of the under 
side is found a prominent narrow portion, the collar-bone (sternum 
collare, 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 peristetliium ; close to which, on each 
side exteriorly, are the scapulae, which sometimes (Cychrus) are soldered 
to the peristethium. Next to the peristetliium, and behind the sockets 
of the intermediate legs, follows the large central acetabulum ; close to 
which, on each side, limited anteriorly by the scapulce, are the para- 
pleura, or side-pieces, which, in many genera (Cychrus), are divided 
into two. Behind the acetabulum and parapleura is placed the 
merieeum, 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 

* Ma 3 as. Vol. V., p. 11, No. L578. 
f Neuc Bcitragc, Book I., p. 11. 



THE THORAX. 73 

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, 
and its broad lateral margin as border (prct) ; 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 pliragma, the posterior margin descending in front of the alitrunk. 
The under side is called antepectus, the central prominent ridge of which 
is called proslernum, 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 
wesothorax, or is divided into the collare, particularly visible in the 
Hymenoptera, it appears to be wanting in insects with a distinct 
manitrunk, the prophragma, 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 clor- 
solum is that portion of the superior surface which lies between the 
collare and scutellum, upon which are found the wing-sockets (ptcro- 
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 medipectus ; 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 metatkorcue. Upon this is 
found the mesophragma, a separating partition running parallel with 
the prophragma, and descending from the anterior margin of the 
metalhorax ; the post-dor solum, the intermediate piece between the 
mesophragma and post-scntelliim ; the post-scutellum, that piece which 



74 PARTIAL ORISMOLOGY* 

follows the middle piece, arid which extends to the end of the meta- 
thorax ; pleurce (the sides), the space between the scapular ia 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 parapleurce, the lateral pieces on each side of the 
mesostethium ; the metasternutn, 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 collars 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 

* Ch. L. Nitzsch, \vho 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. 75 

uniform, without further composition, as in all insects deficient in wings, 
Pediculus, the Mallophaga, Pulex, &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 (dorsuni), 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, Orthoptera, Ncuroptera, 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, ;uul voros, the h;ick. 



76 PARTIAL ORISMOLOGY. 

corneous ridge. The prothoracic case is thereby divided into two lateral 
halves (for example, in Gryllotalpa, PL 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. (Acridium, Latr.) Besides its Disc 
(discus) and MARGIN (margines), we distinguish upon it the surrounding 
BORDER (limbus^). Between this pronotnm 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 distinguisli them from the larger shoulder-blades of the 
intermediate legs (which have been long called scapulae}, may be called 
the smaller or anterior shoulder-blade (pmium*}. 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 
proste.rnum, which extend upwards to the pronotvm. 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 prosternuin, 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 (PL X. No. 3, fig. 1.) 

The inferior plate, the PROSTERNUM (PL 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 (PL 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 scapnln, we have therefore derived it from 
the (.<reek, in which language u>/j.iov signifies a small shoulder. 



THE THORAX. 77 

peculiar (for example, the Cerambycina'), 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, (Acrocintts 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 Lamellicoriiia and Cicadaria display the most remarkable. 
The PATAGIA (patogia) 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 (PL XI. No. 3, 
f. 1 3), they are, nevertheless, h'rmly 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 (PL 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 
pronolum (PL 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 mesothoracic segment when the first pair of legs are separated 
from the prothorax. They, consequently, think they have observed 

* Strepsiptera, Kirby. 



78 PARTIAL ORISMOLOGY. 

that some insects (Fespa, 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, 
Gryllolalpa, &c. &c.); the same remark may be made with respect 
to the COXCB, 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 prosternurn ? The second observation is absolutely erro- 
neous ; for what Kirby and Spence consider as their prolhorax, (our 
pronotum), is sometimes the extended membrane of the neck (Fespa, 
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 pronotnm would 
necessarily 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 collare 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 us 
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, .) In the Hymenoptera and Lepidoptera, this spiracle 
lies beneath the patagitim, and, in the former (Fespa, Scolia, &c.), 
appears as a distinct opening beneath the superior wing. This process, 
which forms a sort of flap, may be called TILE (tegula), for the organ 
which Kirby and Spence have so called is the same with their patagium 



THE THORAX. 'Ji) 

(PI. 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. 

Srdly. 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, ). Besides which, it is here called collare 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 SCAPULA. 

The MESONOTUM (PI. IX. &c. c, c, c. Kirby and Spence's dorso- 
lum and scutellum), forms superiorly the corneous covering of the 
mesotliorax. 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 



80 PARTIAL ORISMOLOGY. 

Kirby and Spenee), 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 mesonoturn is very small, and indicated only by a delicate corneous 
transverse line (PL IX. No. 2, f. 7, c.) ; it is very large in the Melli- 
force and Lepidoptera, as well as in the Diptera ; in the dragon flies, 
(PI. 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 Diptera 
(our pronotum), as Kirby and Spence maintain. The posterior divi- 
sion, the SCUTELLUM (scutcllum), is here seated, as in all, between the 
wings. This SCUTELLUM (PI. 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 (PI. XIII. No. 4 and 5, c, c. ; PI. 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 (PI. 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 Escu- 
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 Boscli, Stratiomys, Sargus, Reduvius). But we more rarely observe 

I 

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



THE THORAX. 81 

such excrescences upon the mesonotum (Clilellarid'). The prominences 
upon the surface of the mesonotum (for example, in Cimbex, Sircx, 
Tabanus, 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 
scapulffi (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 tegulce 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 Hymenoplera being affixed to the mesonotum above the wing, and 
the patagium of the Lepidoptera beneath it, to that part which we 

* C'onsid. (Jen., PI. VII. fip. 6, II. 
G 



82 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 (PL XIV. No. 1, d) in front of 
the base of the wings ; thus also, by reason of its smallness in many of 
the Hymenoptera (punclum 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 collar e of the Hyme- 
noptera, and the same as our pronotum (PL 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), is, as well as the scapulae, divided into two parts ; but here 
they are equal. It is directly opposite to the mesonoium, 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 (PL 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, GryllotaJpa, PL 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. 83 

-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- 
optera, 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. p, 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 
(Tdbanus, Pi. XIV. No. 1. c; Cheh/phus, 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 



84 PARTIAL OR1SMOLOGY. 

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 (Hisler, 
PI. 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 flat, sometimes slightly convex, and 
sometimes distinctly ridged, and occasionally prolonged posteriorly into 
a point (Xiphus metasterni) ; arid when thus, it projects over the 
abdomen (Hydrophilus). It differs considerably in extent in Qryctes 
(PI. 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 Orlhoplera very slightly. 
In these, likewise, the metasternum is a clearly distinguishable, but 
undivided plate, placed between the acetabula of the four posterior 
legs (PL 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 Uymenoptera, the construction of the meta- 



THE THORAX. 85 

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 Scotia (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 coxse 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, ft). 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 halteres (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, Gryllotalpa, 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 parapleurse, and in these 



80 PARTIAL ORISMOLOGY. 

insects, from the two pieces being united posteriorly, it appears as a 
small triangle* beneath the cavity where the abdomen is affixed (PI. XL 
No. 3, f. 3, j). In the Hymenoptera, Lepidoptera, Diptera, 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 PARAPLEURJE (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 (PI. IX. No. 3, f. 6, H) ; in other cases, three- 
sided (PI. IX. No. 2, f. 8, H) ; and very large and trapezoida lin Gryl- 
lotalpa (PI. XL No. 1, f. 8, H), as well as \nLibellula (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 XL 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 halteres 
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 (halteres 
nudi), or else they are covered by one or two delicate SCALES (squama}, 
which are attached to the mesothorax, 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 parapleurae are 
advanced in front of the pleunc, and these united posteriorly into one piece. 



THE THORAX. 87 

78 a. 

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 protliorax, mesothorax, 
and metatliorax, but unites the two last divisions as tronc alifire. 
Each of these segments is subdivided into the upper, or DORSAL, and 
under, or PECTORAL, part ; called also conque 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 prce- 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, torn. 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 preescutum, or the 
anterior deflexed margin, which, in the mesonotum, becomes the pro- 

* Essay sur le Vol. des Insectes. Paris, 1 832, 4to. 

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



88 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 postscutellum, 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 epimeruin 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 parapleurse. 

After Audouin, Straus-Durckheim * and Macleay f 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 TAnat. comp. des Alii. Articiil. Par. 1828, 4to. p. 76, &c. 
f Zoological Journal, Vol. v, (1830), No. 18, p. 145. 



THE THORAX. 89 

pterum, a part unknown to me ; the ties or ilialiques, our scapula, and 
the sternum moyen, our mesosternum. His metathorax consists of the 
clipeus, our metanotum ; the clamcule posterienre, 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 Macleay 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 clamcule 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. 91 

ORGANS OF MOTION UPON THE THORAX. 
A. The Wings. 
79. 

The organs of motion are of two kinds, either WINGS (aloe}, 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 (jieurcg, vence, costte^), 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 Dictyotoptcra, and many Hemi- 
ptcra homoptera. 

2. The anterior corneous or pcrgamentaceous, the posterior 

membranous : 

A. The anterior corneous. 

a. Entirely corneous, Coleoptera. 

b. Half corneous, half membranous, Hemiplera 
heteroptera. 

B. The anterior pergamentaceous. Orihoptera, and some 

Hemiplera homoptera. 

II. Two membranous wings. Dipicra. 

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 



92 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. 93 

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 (Aptinus}- 

FASTIGIATE (fastigiatct), 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, .<:. amplificata), when the edge of the exte- 
rior margin is very high and prominent (Dyticus latissimns.) . 

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

According to their inclination we distinguish 

EVEN (piano) elytra, the whole superficies of which is upon one 
plane. 

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

TURRETED (turrita), 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 



94 PARTIAL OIUSMOLOGY. 

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, PI. XV. f. ] . ), 
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- 
ELYTRUM (PL XV. f. 1, 6), 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 (PI. XV. f. 1. c), which is 
frequently wanting, follows the HEMELYTRUM; 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, PI. 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. 9f> 

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 ( Gryllus, 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 (PI. 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, Locusturia) . 
It varies considerably in figure ; it, like the marginal area, is sometimes 
a very pointed isosceles triangle (Gryllodca); 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 (/) 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 



96 PARTIAL ORISMOLOGY. 

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 (costce}, or more properly VEINS (nervae), as they are, in fact, 
vessels, but incorrectly called NERVES (nerod), 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 
(costa marginalis, PI. XV. a, a), or, by pre-eminence, the RIB (cosla), 
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, /3). 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 posfcosta (PL XV. f. b, b, b) ; Jurine, cubitus ; and Latreille, 
itcrviif. 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 wins; ; but 

O ' 

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. 97 

are called AREOLETS (areolte), or CELLS (cellules, Jurine) ; and those 
lying close to the marginal rib are called MARGINAL AREOLETS (areolee 
marginales, PL XV. d, d) ; Jurine's, cellulce radiales ; those succeeding 
to them, and formed by the postcosta and its branches, SUBMARGINAL 
AREOLETS (ctreoltB submarginales, PL XV. e, e) ; cellulce cubitales of 
Jurine. The transverse veins which branch from the longitudinal 
nervures of the main stems, are called the CONNECTING VEINS (venae 
anastomosis), or nervi recurrentes of Jurine. The areolets seated 
at the end of the wing, and, sometimes not quite closed, are called 
IMPERFECT (areolce imperfects, PL XV. J\ f), or cellules incom- 
pletce 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 Tent.hrcdonodea ; for 
example, Perga, &c.). 

The space behind the second principal vein of the wing is its third 
and last chief areolet, Avhich, in many cases (Hymenopterd), 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 cellula; 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 rind 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 analis 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 (Forficiihi) , 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; 

H 



98 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- 
r lores) 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. secundarice. 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 
(falcatcB, PL XV. f. 12) are wings whose anterior margin forms a circle 
bending outwards, and their posterior margin is also directed forwards 
(many Lepidopterd). 

TAILED (eaudatce, PI. XV.' f. 13) are those which have a long and 



THE THORAX. 99 

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 squamosas). 

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 planet), are those wings which, in a state of repose, 
preserve the same extension as when in motion. 

Opposed to them are the FOLDED wings (plicatce). 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. convolutce] , are such which embrace the 
body from above downwards, and enclose it as in a tube (Crambus). 

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

CROSSED (cruciaice), 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 
(erectce), 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 (patentee) by the angle which they form with 
the axis of the body? being at least of 45 ( Tabanus, Musca, &c.). The 
ERECT-OPEN wings (erectee 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 (divaricate), are such which only partially cover each 
other (Agrion). 

DEFLEXED (defle.vai), 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 bevond 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 (pecles), 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 ACETABULA (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 
(coxae, PL XVI. f. 1, ). 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, llu- 
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 (PI. XVI. 
f. 1, 6), stands in moveable connection with the coxa. The form of 
this part is subject to many changes ; we sometimes rind 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, PI. 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 
coxa? armed with a spine belong to the rarer exceptions ; these we 



102 PARTIAL ORISMOLOGY. 

observe among some of the Ichneumons (Icli. melanogonus, Grav. ; 
Pimpla mesocentra, Grav.) 

IV. The fourth joint of the leg is the SHIN (tibia, PI. XVI. f. 1, rf.) 
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. 
Jimbriatce), and setae. 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 (Chalets'), 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, PL 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, <?.) 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 (pentamera), 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 (Jieteromera) , 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). 

TRIMEROUS (trimera), feet with three joints. 

DIMEROUS (dimera), 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 Carabi 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 (AteucTius, 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 ORISMOLOGV. 

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, PL 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, PL XVI. f. 0), 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 ofDytieus, PL IX. No. 2, f. 8), as FIXED (Jixce}, and the moveable 
ones, which turn in the socket, as FREE (liberce, PL 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 (Jloccatce, for 
example Andrena, PL XVI. f. 8). 

2. TROCHANTER. Kirby and Speuce call it FULCRANT (fulcrans) 
when it is continued for a space along the thigh, thereby strengthening 
its union (Carabus, PL 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 teetli 
(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). 

SCOPATK (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 Ca.ra.bus). 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 Brachycerus, 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 X?/a. 111. (Tridactylus, 
Latr.*) only having actually two equally long toes (PI. XVI. f. 19). 

* See Chaqientier, Hora Entomologies. Vrat. 1 825. 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, PATELLUL^E, 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 inCarabus (f. 21) ; and but 
seldom only one joint is dilated (in Hydrophilus*). 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 stifi 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),\)y 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^ 
simpliceii), but also BIFID (ung. bifidi or Jissi, Meloe, Tetraonyx, 
PI. XVI. f. 27), sometimes armed beneath with one (Melolontha, 

* Ste his Monographic dcr Zabroidcn. Berlin, 1831. 8vo. 



THE THORAX. 107 

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

Between these two hooks of the terminal joint, we perceive in some 
insects a second smaller cla\v,called the SPURIOUS CLAW (pseudonychiaj, 
but by Nitzsch empodium. Among the beetles, we find this structure 
in Lucanns (PL 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, PL 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, PL XVI. f. 33) ; still, 
more seldom, are both wanting as well as the larger claws (Xenos, 
PL 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 (ptdvillus). It 
consists very generally of short and stiff hair (Lamia, PL XVI. f. 35), 
more rarely of radiating plumes ( Zabrus, PL XVI. f. 36), occasionally of 
true fleshy cushions (Xenos, PL XVI. f. 34). Some genera ( Timarcha) 
display minute cup-shaped hollows in the sole, which is then called 
SPONGY (pi. spongiosa, PL 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 appeal- 
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 Hymenoplcra. Tr. 



THE ABDOMEN. 109 

additional and proportional consistency and firmness. This part is 
called the BELLY (renter) in contradistinction to the upper superficies 
corresponding with the breast, which is named the BACK (dorsuni). 

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 by the 
wing-cases. 



110 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, Dictyotopfera, 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. squamatiis). 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. haslatum) ; 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. (datum), when the projection of 
the margin is very considerable (Coreus quadratus, many Ting-is). 
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 
Heiniptera, 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 OJIISMOLOGY. 

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 Libellults, 
narrow, round, and spinose upon their inner margin in many Noctuce ; 
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 Mt/opa, 
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 
( Vespu). 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. J, c, and 
f. 12) to receive the rest (the same, f. 7> d, f/). It possesses, besides, 
two lateral VALVES (valvulee, 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 (terebru). 

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, PI. XXIV. f. 10 ) consist of two long, convex 
continuations of the abdomen, generally inclining upwards, which, when 

* Meigen. Zwcif., 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 (forcipes, PI. XIV. f. 8), two toothed cheliform 
hooks, which move in opposition to each other, in the earwig. 
(Forficula.} 

The FORK (furca, PI. 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, 
Smynthtirux.') 

The STYLES (styli, PI. XIV. f. 10), two short exarticulate processes, 
close to the anus in Staphylinus. 

The CERCI (cerci, PI. XIV. f. 11), likewise short, lanceolate, and 
generally flattened and articulate appendages at the sides of the anus. 
(Blatta.) 

The THREADS (fla, PI. XIV. f. 12), longer or shorter articulate 
cylindrical processes of the last segment, which grow gradually thinner. 
(Acheta, Ephemera, Lepisma.) 

The BRISTLES (setts, PI. XIV. f. 13) are such appendages when 
exarticulate and simple. (Mackilis.) 

The SIPHONETS (siphunculi, 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 

o 

is distinguished by the name of ANATOMY (derived from avare/jiVEiv, to 
cut up) ; but the portion of it which treats of the interior structure of 
insects might be appropriately called Entomotomy (derived from IVTO- 
p.ov, insect, and ripvtiv, 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 NUTRIMENTAL 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 
power 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, 

i2 



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 VESSELS, 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 



1 1 8 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 larva? 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 mxist 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 (Lamellicornid), 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 
ve&icular form, they being always closed at one end at least. 



THK ORGANS OP 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 unassiuiilating 
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 (inem- 
brana propria), is white and smooth, and usually thin, but sometimes 
thicker and spongy, most frequently without any texture, but occa- 
sionally figured (Hydrophilus, PI. 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 (glandules gastric fe^). 
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 (PI. XVII. f. 3.). 

The third layer (PI. 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 their 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, Agrion). 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, Ranatrci), 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 Verdanungswerkzeuge der Insecten Halle, 1811. PI. XIV. 
f. 4, from Pompilus Viaticus. 

f The same PL XVII. f. 2., from the fauces of the larva of the Ant-lion. 



]22 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, Cimcx) 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- 
cornia, 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- 

* Ranidohr, PI. 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 ccecum 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, Orthoptera, Neuroptcra, 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 ' t 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 

* Ramdola, ib. PI. I. f. ( J. 



124 



ANATOMY. 



distinguish the proper membrane between them as a separate layer. A 
free space is naturally not found, as in the stomach. 

THE (ESOPHAGUS. 
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, Fcemts) ; 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 canal f ; 
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 Schriftcn, vol. ii. p. 200. 

f In Pimpla Enervator and Pompilus viaticus, Ramdohr, PI. III. f. 2 and 3. 

t Ramdohr, PI. III. f. 1. 



THE ORGANS OF NUTRITION. 125 

Meloe, Chrysomda, 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 there between 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 GryUotalpn 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-]-. 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 Sucko\v,in Reusing. Zeitschrift. f. d. Org. Php. vol. 3. p. 53. PI. II. f. 134. 
f Gattungen dcr Tliier-Inseckten, Germar's Magaz. iii. p. 280. 



126 ANATOMY. 

fluids in the proboscis and oesophagus. Insects which chew 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 
denned 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 Lepidoptera (PL 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 Zyg&na 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 pint 
and Cossus ligniperda ||. 

Many Neuroptera, 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 Phryganea) than by mastication. 

* For example, in the Tenthredos and Ichneumons, Ramdohr, PL XIII. f. 2 and 3. 
and PI. XIV. f. 2. 

f Ramdohr, PL XII. f. 6. PL XIII. f. 1. PL XIV. f. 3. Treviranus, PL XIV. f. 3. 
and PL XVI. f. 3. 

* Ramdohr, PL XVIII. f. 1. 

Trevirauus, PL IX.v,v II Ib. p. 109. 



THE ORGANS OF NUTRITION. 127 

In the Diptera, lastly, (P). XVIII. f. 2 and 3, c, c,) 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, at 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 (honigbehdlter), 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 Hemiptera, 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. 810) 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, 
Hydrocantharid.es, Brachyptera), the wood-beetles (Cerambycina, 
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, PI. XVIII. XXL, and Trevir.Pl. XVII. 
t See Ramdohr, PI. XXI. f. 6., and PI. 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 (Cidndelacea 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 Stapkylinus 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 (Cerambycma) 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. ], Lamia cedilis}. The Ortkoptera (for 
example, Acheta,) 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. 14. 



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. 
Miiller -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. Mecl. n. cur. T. 12. B. PI. L. f. 2. 
f Job. Miiller de Glandul. Secern. Struct. Pen. p. 68. Lips. 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 Acheronlia 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 (Sirex) 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 Alhericera, have peculiar, glandular, 

* Verglci. Anatomie, vol. iv. p. 87. 

f Compare Treviranus, Vermischte Schriftcn, vol. ii. PL XV. f. 2. 

J Compare Suckow,in Heusinger Zcitschr. f. (1. 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 Orthopterja, 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 Libellulee and Ephemerae: 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 Dicty- 
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 Coleoptcra 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., 
Scarabcens, PI. XX. f. 2., Melolonlha, 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, Ulster, 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 Ramclohr, PL XX. and XXI. 
f Ch. L. Nitzsch, in Germar's Magaz. der Entomol., vol. iii. p. 280. and vol. iv. 
p. 277. 

K2 



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, Callichroma 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 (as Lytta, Mylabris, Mcloe), 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 Coleoptera (PI. XIX. f. 4. n, 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. Gade, in the Nova Acta Phys. Med., vol. xi. part ii. p. 329. ; and 
J. F. MeckeFs Beitriige zur Vergl. Anat., vol. i. pa-t ii. p. 129. 
t Ramdohr. PI. XI. 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 Brachyptera, 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 Gryttotalpa, 
and as many in Locitsla, but here shorter, and more vesicular. In 
Gryllus migratorius I found six tubular ones (PI. 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 alse 
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 Hcmiptera, 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 Cuicoptera 



134 ANATOMY. 

and Orlhoptera. With respect to its precise form, it is smooth 
and cylindrical in Nepa, somewhat wider and transversely ringed in 
Lygteus, shorter but wider, with irregular longitudinal folds, which 
form apparent large pockets, in Cimex. In Cimex rujipcs 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 rujipex, 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. 
nt/ipcs, so that their third stomach properly consists of four contiguous 
stomachs t- 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 (PL 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 

* Ranidohr, PI. XXII. f. 8. 

f Compare O. R. Trevirauus, in the Auualcn clcr Wuttcrausch. Gesellsch. sur Uie 
Naturgcsch, 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 ; 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 abdomen, 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 a'dilis,') 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 (Sitpha, 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^, Silpha J). A 
stronger ringed constriction separates it from the following portion of 
the small intestines. 

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 

* R^m.lohr, PI. IX. f. 6. f Ib., PI. V. f. 1. : Ib., PI. IV. f. 2. 

Ib., PI. XV. f. 4. || Ib., PI. XXV. f. 5. 



THE ORGANS OF 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 
>eculiarities 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 (Necrophorus), 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 Libcllulcc 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 Necrophorus, 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 Ramdohr, 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 Lamellicornia (Mclolotilha, 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. r) ; 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 rig. 2.) this bag is to be distinguished exte- 
riorly only as a bellied distension of the ilium, which, at least in Mclo- 
lo/tt/ia, 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 Ucusinger, vol. iii. PI. . f. 04. Straus Duvckheiui, PL V. f. 8. 



THE ORGANS OP 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 (Carabodca) , 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 I-OAV lies where in the upper 
one is found the intervening space. This structure Suckow first 
observed in the bees f. I found in Harpulus riijicornis a perfectly 
similar structure of the colon, these fenestral spots were in the internal 

* Vcriuischtc Scliriftcn, vol. ii. p. 105. PI. XII. f. 3. 
t In Hcusingcr 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 CAECUM. 

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 4 G, 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 (Stlphu) and directed forwards, some- 
times laterally distended (Necrop/wrus) , 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. ]41 

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 (Melolonthu, &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- 
oplera, 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 billfera, (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 ap/erus. 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 

* E Salv^AU, ^ j#, t 

"'' 3o ,J. JT8; (,> . 



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 
(Acliet(i), 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 FOUR 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. 
} . Four biliary vessels. 

a. Free at the end; most Diptera, as well as the families 

Termiiina, Psocina, and Mallophaga, of the order 
Dictyoloptera. 

b. Anastomosing ; many Coleoptcra, Hemiptera, and 

Diptera. 

2. Six biliary vessels. 

a. Anastomosing ; many Coleoptcra, for example, Ce- 

rambycina and Chrysomelina. 

b. Free at the end, Lepidoptera. 

3. Eight free biliary vessels, Neuroptera. 

III. Many biliary vessels, Hymenoplera, Orthoptcra, and the Dic- 
tyotoptera subnlicornia. 

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 Cerambyclna, 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, Melolontha) ; but they are short, on the contrary, 
where they are numerous, for example, in Gryllotalpa, 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, Carab^ls, 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 saffron 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 Raradohr, PI. XIT. 



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 Hyrdophilns) 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, PI. 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, PI. 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 (PI. XXII. f. 2). 

7. As capitate tubes, in the free ends of which many very fine 

vessels empty themselves (Tabanus, PI. XXII. f. 4). 

8. As tubes which at intervals are surrounded by twirling blind 

bags (Cicada, PI. 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 

his, PI. XXI. f. 12.). J. Miiller observed such granulated 
salivary glands in Phasma ; Treviranus in Apis ; and I 
have found them in Locusla, Gry/lns, 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 Hemerofrius perla (PI. 
XXII. f. 4). 

2. As two short processes of the same width as the stomach, in 

Leptis (PI. 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., (Edemera, Mycterus, Mordella, &c. I have found them of the 
above form among the Orthoptera, in Locusta, 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 Orlhoptera 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. 

L 



146 ANATOMY. 

Where we meet with salivary vessels we generally find two ; some 
insects have, on the contrary, four, each pair of which 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 diiferent 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 
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. XXI. f. 13), and remain even in 
the perfected moth ; whereas the spinning vessels totally disappear 
during the pupa state f . 

In Myrmccoleon the spinning vessels lie at the anal end of the 
abdomen, and true salivary vessels have not yet been observed in it +. 

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. uber Insecten und Krustenthiere, p. 28. PI. VII. f. 32. a. 
f Ib.p. 29.P1. II. f. 1 10. h. h. 
+ Ramdohr, PI. 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 Heleromera (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 t. 

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. PI. 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 auratus 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 Jtumeralis; 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 Chl(E?iius 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 velutlnus] 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 larvae 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, 
Orthoplera, and Dictyotoptera, 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, 



THK ORGANS OK 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 Libellulfs 
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 Dipt era (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 (Myrmecoleon, 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 marginalia, according to Dutrochet, whose investigations 
I have repeated, and can now confirm (see PL 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 OK 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 Dylicus, 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 nutrimental 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. 

nutrimental 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 Gastrophaga quercus 
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 fattv mass cannot be the liver. 

tf 

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 r 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. 

11G. 

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. Chemic, vol. ii. Div. i. p. 469, No. 24, ;md 
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 Muller, 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 
Melolonllia, I could observe but four on each side in the larva of Calo- 
soma. According to Midler's description of the heart there appears to 

* Compare his Dissert. Boinbyce. Lond. 1669, 4to. or his Collective Works, Lugd. 
Bat. 1687, 4to., vol. ii. p. 20. 

t Entdeckung eines cinfachen, vom Herzen aus bleschlcunigten Krcislaufes in den 
Larven netzfliiglichcr Insckten. Leipz. 1827. 4to. 



THE ORGANS OF DIGESTION. 155 

be but one aperture in Phasma, 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 which 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 



150 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 (fliigel) 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 (Ecl'dis}. 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. \Yhen 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 (PI. XI. No. I. f. 7- a], 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 Gri/l- 
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. Miiller discovered a union 
of the ovaries with the aorta . We shall treat in greater detail of this 

* Cornp. J. Miiller, iiber das Ruckengefass, in Nova Acta. Med. Nat. Car. vol. xii. pars 
ii. pp. 576 and 586. 

f Ibid. p. 596. * Joh. Miiller, 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 BRANCHI^:. 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 OP 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 (PI. XI., No. 1, f. 2, 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. 6.) 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 AXATOMY. 

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 (PL 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 Cams, Analekten zur Natunvisscnscli. Dresden, 1829. 8vo. P. 187. PI. I, 
f. 13. And Sprengel, Commentar. &c. Plate II, fig. 23; and Plate III, fig. 29. 
) Das Organische Leben, nen dargestellt. Bremen, 1831. 8vo. Vol. I. p. 2.58. 



THK OKGANS OK HKSPIRATION. 101 

as in the branchiae, through the plate of the spiracle. Buth 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 Sprengel's 
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 CoJeoptera 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 scapulas. 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 

M 



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. /i). 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. (Acri/dium, 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 B/attaria, 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 Forjlcula ; 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 Hemipfera, 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-shaped, 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. /3) 
lying over it, and above it is concealed by the elytra. The succeeding 
spiracles are in these insects, as in the Ortlioptera, more approximate 
to the ventral segments, a spiracle being placed in each abdominal seg- 
ment, whereas 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 OP RESPIRATION. ItvJ 

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 rujipes and P. hce,morrlioidalis) 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. 
Semblis displays two distinct pairs (PL 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 Libellula? and Termites, they are, from 
their minuteness, difficult to investigate. The Libcllu/ce 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 f 
observation of their respiration through the anus. This intestinal 
respiration Suckow J 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 pro-? 
thorax, between it and the meso- thorax, and the other two lie between 
the meso- and meta-thorax. In the Hymenoptera, 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-) li es precisely beneath the anterior wing, and is very 
readily recognisable in the wasps. In PI. XII. No. I. f. 1., wherein the 
thorax of Cinibcx is represented, the letters a and /3 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 /3, 
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 shown 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. r.nd III. 

Reusing. Zeitschr. fur 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 (Dyticvs)'. According to Degecr and La- 
treille *, the locusts and Lepidoptera display as many : the Lamelli- 
corniaand 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, Rannlra}, 
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 quelqucs Appendices du Thorax dcs divers lusectes. In Mem. du 
Museum d'Hist. Nutmvllc, turn. vii. 



166 ANATOMY. 

thorax (PI III. f. 4). The majority of the larvae of the genera most 
closely allied to this gnat possess no such air tube, hut true branchiae 
or gills, yet the larvae of Citironomus* 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 t, as well as 
by their blood red colour, from the true larvae of the Culicidcc. 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 setae, 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 larva 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, 

:;. is, n. 

* See Swammerdammj Biblia Natuiw, I'l. XXXIX. f. 1 ;',. 



THE ORGANS OP 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 Diptera, but 
also in all larvae which live in water and are unprovided with branchiae. 
With respect to the larvae of the Diptera, those yet investigated have 
their spiracles in that situation: for example, the flies and (Estridce. 
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 *. 

120. 

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 branchiae seldom appear singly, but generally in 
approximate fasciculi, which are formed by either the ramifications of 
one or of several main stems (PI. 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. 

* CoinmcnUu-., {.. ','>!. N... 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 Jusco-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 Culeoptera we find hairy branchiae in the larvae of the 
whirlwigs (Gyrinus t), 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 +, 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 Ephemera 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 
LibellulcB 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, M^moires sur les Insectes, vol. ii. part ii. p. '29. PL XVIII. t'. '.'>. 

f Ib , vol. iv. PI. XIII. f. 1C 19. 

J Inscctenbelustignngen, vol. ii. Vv';is>cr-In<crtrn d. Ki>t. Klassc, p. 3'2. Fl. IV. 

DC Gccr, ih. PL XVI. f. ;5. 



THE ORGANS OF RESPIRATION. 169 

clavate leaves fringed at the margin. The larvae of JEschna 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 |). 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 IF 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. PL I. and II. 

t Ib., p. 27. PI. III. f. 24. 

t Compare Thon's Archiv. der Entomologie, vol. ii. no. ii. PI. II. 

Beschaftigungen der Berliner Gesellsch. Naturfors. Freunde, vol. i. p. 359. PI. VIII. 

|| Wiledeniann's Archiv. fur Zoologie und Zootomie, vol. i. No. i. p. 108. PI. III. 

5f G. Fischer, Sur quclqucs Diptcres de Russie. PI. I. f. 1 16'. 












170 ANATOMY. 

with two curved air tubes between the pro- and mesc-thorax (PL 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, larvae 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 branchia, 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 TRACHEA, we shall find 

* DeGccr, vol. i. jart iii. PL XXXVII. f. .3 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 librous, but hard, and generally 
colourless. Coloured tracheae, which we now and then observe, for 
example, brown in Locusta viridissima, red in Phasma gjgfis, 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 

* Commcutar. tie Par!., &c PL II. f. 14. 



172 ANATO3IV. 

separated by broader membranous spaces, these he has figured as 
round in Cetonia aurata * : 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 

* ConniicnUir. dc Pad. 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 : 

1. 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 tracheae 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 we 
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 

o * 

* Marcel de Serres, Mem. du Museum, vol. iv. PI. XVI. f. 1. 



THE INTERNAL ORGANS OF RKSPIRATION. 175 

insects we 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 larvee 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 Coleoptera this is the case in the larvae of 
Dylicus and HydropTiilus. The yellowish green larvae, figured 
by Roesel * of the large water-beetles (JDyticus marginalis, d'nni- 
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 

* Insectenbelustiguugen, torn. ii. Wasseriiisekten der Ersten Klasse, p. 8. PI. 1 
f. 2-7. 



17f> 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 
oratorio 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, Avhich 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, qucsd. dc Insector. Vcrmuniqiie Structure. 
Chilon, 1817. 4to. 

t M<;m. du Museum, torn. iv. PL 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 (Cw/e.r) 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 (PL 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 Hi/menoptera 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. Natuno, 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 ( Muscidte) the Syrphodea 
and the (Estridce, 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 connect- 
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 Swanimerdam Biblia Natune, PI. XXIV. f. 1. in Apis Mellijica. 



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 | 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 Locusla 
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 



. de Mus., as above, p. 362. f Journal de Physique, Sept. 1830. 

J Analekten zur Naturwissenschaft und Heilkunde. Dresden, 1828. page 158. fig. 
1517,9. 

N2 



180 ANATOMY. 

organs. Thus, therefore, the air bladders of the abdomen form a com- 
pact net-Avork, 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. ; i 
t Biblia Nature, PI. XXIX. f. 10. J Commentar., PI. I. f. 1113, 



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 Melolontha. 

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 Lamellicornia 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 Phalente, and are sometimes small and sometimes large, 
as in Acherontia 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 

* Commentar., 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 oviductus), 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. Miiller * has shown them, at least in the 

* Nova Act* Phys. Med. XII. 2. PL LV. 



THK 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. OP 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 BIVALVIS. 

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. M'uller in Nova Acta Phys. Med., torn, xii, 
p. 612. does not belong here, but will be classed below, with the ovarium furcatum. 



FEiMALE ORGANS OF GENERATION. 185 

Such ovaries are found in Ephemera and Stratiomys. Muller 
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, I 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 (PL 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 (PL 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, Phryganea, 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, (Coleoptera vesicifica, each tube 
with from one to four eggs; Semblis, each with six to nine eggs). 

5. OVARIA DICHOTOMA (PL XXVII. f. 5. ovaria fur cata, Muller). 
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 (PL 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. f Bib. Naturae, PI. XXV. f. 1. 

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 saccota, Miill.). 
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 (PL 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 Coleoplera. 
Miiller'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. Oryctes nasicornis, Melolontha, Cetonia, 

* Leon Dufour in the Annales des Scienr. Nat. torn. 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 ; Veapa 
vulgaris and Silpha atrata seven tubes ; Tenebrio, Leptura, Saperda, 
Blatta, Ascalaphus, Bombiis 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 (PI. 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. Muller *. 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 Carabus*. 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 Miiller 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 Hydropkilus, 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 Ada Phys. Med. n. c. PL LI. f. 3. f !*> pl - L - f - 2 - 



FEMALE ORGANS OP GENERATION. 189 

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 
lonsrer in this common duct to be covered by the secretion of those 

O * 

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, Erisialis 
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, Semblis, 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 Psocus, 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. ), 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- ). 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 (PL XXVII. f. 16 18. &.) 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 spermathecae 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 Otrmar's Magaz. vol. iv. p. 281. PL II. f. 3. e. f. fig. 4 and 5. 



FEMALE ORGANS OF GENERATION. 101 

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 tivo 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 Siratiomys 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. Natura, PL 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 Fanessa Urtlcce 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 Gastrophaga Pini 
(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 (PL 
XXVIII. f. 5, 6. b, 6), 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 (PL XXVIII. f. 6. 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 
egg-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, PI. 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 Hydropkilus 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 segments if 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, becdme 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 

* Reusing. Zeitschr. vol. ii. p. 254. 
O 



194 ANATOMY. 

palus rujicornis), 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 OP 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 tuln- 
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, viridissimd) even longer than the body, each 
valve is gently sloped, and has a channel upon it's 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, i,) which are connected by a delicate membrane with the internal 
elevated ridge, and sometimes lse 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 Spencc, 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 Locu.sta, 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 Gryllux. In Ctenopkora alrata, 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 Locusla. 
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 Hymenoptera 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 OKGANS OF GENERATION. 197 

vagina bivalvis, but it is indicated in the shorter internal valves, which 
in Locusta 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 STING (aculeus, sen 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, ), 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 exsertus) 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 abscondilus) 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 Tenihredonodea 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 (PL XXIV. f. 8.), like 
the sheath, of two valves (a, a, and b, 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 (PL 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, I), b}, which, like the ridge, is finely ajid sharply toothed ; 



198 ANATOMY. 

raised lines run over the whole of this surface from tootli to tooth, 
and from the elevated ridge to the superior edge, which makes the 
whole exterior surface even, arid 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. .) is channelled beneath, completely smooth, and 
only at its broader point beset with small teeth ; the lower (the same, 
,) 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 Sirex 
(PI. XXIII. fig. 5 11), in which the sting projects, we find likewise 
the exterior valves (a, fl) 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. "]}, the 
channel is split, and that portion as well as the bristle upon its entire 

" Ichneumonologia Europsea, torn. i. p. 89. " Hsec seta terebra est, et canali ccntndi 
longitudinal! instructa esse dicitur, per quern ova poueruntur." 



FKMALE ORGANS OF GENKRATION. 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 con/ince 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, , 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. J.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, 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, b., 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. 

* Bihlia Nsiturae, PI. XVIII. f. 3. f Gen. Cms. et Ins., vol. iii. p. 242. 



200 ANATOMY. 

II. OF THE MALE ORGANS OP 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 DEFERENT/A, 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, 
(Pi. 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 (PI. XXIX. f. 2.). They lie stretched out, 
and are wider 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 JUiformea. (PI. 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 spir ales. (PI. 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 furcatl (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. Testiculi convoluti. (PI. XXIX. f. 7-)- The filiform testis is 
very long, much longer than the abdomen, and convoluted into some- 
times a round (TJyticus), 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 scopacci. (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. (Hydrophilm.) 

2. Testiculi fasciculati. (PI. 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, PI. XXVIII. 
f. 5, .). 

3. Testiculi stellati. (PI. XXIX. f. 14.). From the end of the 
simple sperm duct, short fine, star-shaped or radiating filaments 
originate, (Apate.) 

4. Testiculi flosculosi. (PI. 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, Te.nebrio, (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. (PI. XXIX. f. 11.). The bladders are 

* Suckow, in Heus. Zeitschr. f. d. Org. Physik. vol. ii. p. 234. PI. XII. f. 30. 

Arcording to Swammerdamm, Biblia Natur.v, the testes are kidney-shaped bodies. 



MALE ORGANS OP 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. (PL XXIX. f. 7- 6.). The reflected 
end of the sperm duct feears 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 
Meloii, 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 Callichroma have equal branches: in Lamia oedilis, the 
superior one is longer (f. 18). 

3. Testiculi digitati. (PL 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-compositL (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 capitalo-verticillati. (PL 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 Melolontha 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. 

H8- 

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 Locitsta and Gryllotalpa, the epidydimis forms a convolution of 
vessels. In Gryflolalpa, 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 J. In Locusla, 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 (6.), 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 the 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. 57. Ibid. PI. XII. f. 20. 



206 ANATOB1Y. 

by degrees or at one spot, unite into one common duct. The first case 
is found only in the compound capitate testes ( T. cap. compositi), but 
universally here. Thus the twelve ducts of the twelve glandular 
bodies of Celonia 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- 
canlharides, in Lucanus, the Capricorn beetles, all Lepidoptera, 
Libellula, Ccrcopis, and several others ; as a slight distension at the 



MALE ORGANS OF GENERATION. 207 

end of the sperm duct, it appears in the Lamellicornia, in Senil/tix, 
Tipula ; as a large ovate distension, at the end of the sperm duct in 
Hydrophilus (PL XXX. f. 10.) and Apis ; as a peculiar appendage to 
the sperm duct, in Phryganea (PL XXX. f. 6. &.>.). In Lylta, Meloc, 
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, Donacia, 
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 Blatta only, as 
far as our knowledge extends, make an exception to this rule ; as in 
Tipula (PL 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 Blatta, 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 Carabodea 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 (PI. XXX. f. 13.) ; in Dyticus, 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 ; 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. 6.), 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 

* Beitrage zur Anatomie der Insekten, p. 20. 



MALK OKGANS OF GKNKHATION. 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 Callichroma moschatum. 

Where there are two pairs of appendages, they display the same 
forms. In Ascalaphus Italicus 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 Clerux 
alvearius ; to Gade, in Tenebrio molitor ; and also in Blaps morlisaga, 
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 Hydrophilus, 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 Gade J, 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- 
wards, empty themselves. 

* Bcitrage zur Anatomic der Insekten, Pt. 1. f. 1G. 

f Brandt and Ratzeburg Arzeneithiere, vol. ii. 4 Pt. PI. XIX. f. 13. 

t Nova Acta Phys. Med., vol. xi. p. 331. 



ANATOMY. 

151. 

DUCTUS EJACULATORIUS. 

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 (Hydropkilus), and sometimes contracted 
by degrees, consequently clavate (Lucanus, Lylta'), sometimes simple 
and of equal width. In length it varies much, sometimes short, 
scarcely visible, yet broad (Locusta, Gryllotalpa), sometimes longer, 
but yet, in proportion to the other internal sexual organs, still short 
(Calosoma, Melolontha, Trie/tins); moderately long when it attains 
about the same length as the sperm ducts (Hydrophihts, 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 white 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 OP GENERATION. 2 1 I 

into the penis. In the other Capricorn beetles (for example, Cullichroma 
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 prae- 
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, Fabr., PI. XXV. f. 14.), in which the 
withdrawn penis extends to the commencement of the thorax, the prae- 
putinm 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 ejacnlatorius. 

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 OP 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. 6). 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 (PI. 
XXV. f. 9. .), 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 (PI. XXV. f. 11 14.) approaches very 
closely in many particulars to that of Dyticits. 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. P ; ) is not bivalved. as in Dyficns, 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 (JT) is 
enclosed by two small horny arches. 

In Melolontlia 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 
strons membrane : between them lies the membranous canal of the 

o 

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 Orthopiera 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. o), 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. 
0. ), with which laterally the right dorsal valve which bends upwards 
(f. ti. /;) is united by means of a flexible membrane. The yet remain- 

* See Straus, as nhove, PI. III. I. 5., PI. V. f. 13., and PL VI. t. ]. 



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- '<O and the central unequal upwardly bent spine, 
which is furnished at its extremity with a barb (f. 7- ^ ) 

The comparison of this organ with that described in the Coleoplera 
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 Cimbcx 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, b~), 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. d.~) 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 PL 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, ). Between these exterior ones the inner ones lie (the 
same, b, 6) ; 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, 
), and has upon its superior side a deep almost tubular channel, 
through which the semen is ejected. 



210 ANATOMY. 

The male organs of the Lepidoptera (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 a pergamen- 
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 was 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 
Tiptilaria I formerly described a new insect (Nematocera nubectilosa), 
which was 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. Mcigen's Systematische Beschreibung tier bekannten Europaischen, zueifliig- 
ligen Insekten, 6. B. mit Kupfem, 1818 32. 

-f- Comp. Thon's Archiv. dei Entouiolngie, vol. ii. p. 36. PI. I. f. 13. 



MALE OKGANS 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 Dolickopodea. 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 Nematocera. 
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 Avhich 
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 the larger 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 
pronoturn 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 Libellulee, 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 GROANS OF GENKRATION. 219 

and the anterior aperture the extremity of the cluctus 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 (A, 6), 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- fl )> 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- b) ; it is united 
to the first by a joint, and can, 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. Z>), 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, r.). 

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 
Brassica, 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, 

' Entwickelungsgeschichtc dcr Schmetterlinge. Kapcl and Marburg, 1815, 4to. uith 
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 the 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 ( Libc Hulce); 
ramose bunched testes with similarly formed fasciculated ovaries 
(Locusta, Gryllotalpa ) ; compound, radiating, and united testes with 
similar radiating or twirling ovaries (Lamellicornici) ; indeed, some- 
times the number of the single bodies in the testes agrees with the 
number of the egg tubes (Meloloniha, Trichitts). 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 displaya 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, arid 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. 



THK ORGANS OF MOTION. 225 

157- 

The nerves consist of filaments formed of consecutive globules, which 
are enclosed by delicate membranes, the nervous sheath (iieurilema), 
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 such 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 

Q 



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 HORNY 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 membranoxis 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 the 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 marginalis, &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, Low is it ,that so many insects, namely, the blue metallic or aeneous ones, retain 
Lir colour in this fluid, and onlv 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. 

J. 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, and 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, Menelaus, 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. 053. 7), hydrogen (7. 32. 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, vol. iii. p. 254. PI. XLIV. f. 5 8. 

f 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. Atitkor'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 chitiiie, 
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, v 
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 (proslernuin) , and the SHOULDER PLATES (omia). 

The second or MESOTHORAX exhibits four, six, or seven plates. The 
simple DORSAL PLATE (?nesonotum) ; the sometimes simple, sometimes 
divided BREAST PLATE (mesosternum}, and the two, also sometimes 
simple, or likewise divided SHOULDER PLATES (scapula;). In many 
orders (Diplera, Hymenoptcra}, the three or six last are connate, and 
form ONE ring. 

The third or METATHORAX has, like the middle one, either two, 

* Compare Aug. Oilier Mem. sur la Composition Cbemique des parties Corn^es des 
Insectes, in Mem. do la Soc. d' Hist. Natur. de Paris. Par. 1823. T. i. p. 29, Straus 
Durckheitn, p, 32, and Mr. Children in Zoological Journal, vol. i. Ill -115. 



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 (mefasternum) ; between the two, the 
SIDE PLATES (pleurce}, and AUXILIARY SIDE PLATES (parapleurce), 
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 Hymenoptcra, 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 Libdlula; 
among the Neuroplern 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 an arch, forming a narrow cover, 
which is attached in fi-ont to the frons by means of two other pro- 
cesses. I call this cover the tentorium, because, as in the higher 
animals, for example, Fells, 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. 

165. 

INTERNAL SKELETON OF THE THORAX. 

In the structure of the thorax, the Hemiptera, Orthoptera, Neu- 
roptera, and Coleoptera 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 Apodemala 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 rnesonotum, 
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 Diptera. 
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 ( 7478.), 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 (PL 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 
coxa 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 Cimbex 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 coxse. 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- 
toma 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 pleura?. 

The skeleton is much more perfect in the Orlhoptera. 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 opponent, and thus covers the nervous cord (PI. XL 
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. \>, 6). 
The superior partitions, the meso- and metaphragma are small, and do 
not lie vertically but obliquely, whence the cavity of the thorax acquires 
much compass and wide avenues. The most perfect skeleton amongst 



THE HORNY SKELETON. 237 

the Orthoptern is found in the mole cricket (Gri/llottilpa vulgaris). In 
the prothorax (PI. 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 
(PL 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- a), 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 Neiiroptera are very similar in structure to the grass- 
hoppers, at least I found in the Termites 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 (Cattichroma, Saperda,) and all 
the Rhynchophora, are connate *. In Carabux, 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 (Qryctes). 
Above, this process has a tooth on each side, which bends towards the 
side of the prothorax, and sometimes unites with it (in Hydrophilus, 
PI. X. No. 3. f. t> and 7- a, a). 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 interims 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. Anatomic, vol. ii. Part i. 
?. 70. 



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 coxa? 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 smajl channel, 
in which the intestinal canal rests. In Dyticus it even furcates, and 
with both prongs of the fork it encloses the intestine, and lower 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 ; 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 coxee, 
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 cull the postfurca, Audouin, on the con- 
trary, styles it, in connection with the preceding ones of the pro- and 
mesothorax, the entothorax *, we rind but a few other ridges produced 
by the sutural connection of the pleurse 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 OF 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 respifatory 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 (si/narthrosis}. This kind of 

* See Meckel's Deutsche Archiv., &r. torn. vii. p. 440. 
[ f Mem.de Musee, torn. 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 piate 
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 (Diarthrosis). 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. 

R 



242 ANATOMY. 

2. GYNGL.IMUS. 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 ; whereby 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 FREE 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 Coleoptera, 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 
(tlydropliilus piceux, 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, Orfhoptera, &c., in which we 

R2 



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 tiniest. 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. 

t I have since detected the spiral fibre in these vessels, and observed that they are 
genuine tracheae Authors 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 Coleoplera, Orthoptera, Dictyoptera, Neuroptera, 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 Melolontha four such plates, and called them shoulder 
pieces (\.pre-epauliere, and S.epaulieres). From the posterior margin 
of the internal process of the joint of the superior wing, a delicate 
semicircular membrane springs (frenum 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 

* Siir le Vol de* Insectes. Mem. clu Musec, torn, vi viii. 



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 Dipt era 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 Coleoptera 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 (\.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 Orlhoptera as 
well as of the Dictyotoptera and Nturoplera, 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 booklets, 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 

* Mm. pour servir a 1'Hist. des Insecles, t. i. p. 173. 
f- Trans, of Linnsean Society, vol. i. No. 7. Lond. 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 
lamina? 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 

* Consid. 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, anil 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 Locusld) . 

4. PENNIPORM 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 Mcckel'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 winajs are formed in this manner. Audouin 

o * 

considers these horny tendons as processes of the thorax, and he calls 
them Epid ernes. 

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 (adductores sen 
jlexores), lie on the inside of the limb, and draw it to its base, to 
which it is affixed ; the others, or EXTENSORS ( abductores seu 
exlensores), 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 OP 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 
antennte. 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 (elevatores capilis), 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 extend). 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 
prostermun, 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 eocterni). 

The rotatory muscles of the head (rotalores 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, (Diplcra, Lepidoptera, Neuroptera, 
Dictyotoptera, and Hymenoplera,') 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 aflixes 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 aflixes 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. basilaris 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 maxillae together. 

Two other muscles, which likewise move the entire maxillae, 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 Avail 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 maxillae. 

The galeae, 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, whieh 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 maxillae, 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 Mdolonlha 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 : 1 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. 



THK MUSCULAR SYSTEM. 257 

175. 

B. MUSCLES OF THE THORAX. 

The muscles of the thorax must he considered under several points 
of view, which proceeds from the differences of structure displayed in 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 



2")8 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 posterieure 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, Vabaisseur de I'aile 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 (mitsculi laterales metanoti, les pretrac- 
teurs de I'aile 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 I'aile. 

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 (mus- 
culi furci-dw sales.) They are the Jlechisseur lateral de rapophyse 
episternale posterieure, I'abaisseur du tergum, et I'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. 

s2 



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 magnus) 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 Lepidoptera, 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 (Jlexorcs 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 axillaire trolsieme 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 coxas 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 coxse 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 coxa? 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 coxae 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 Melolontha, 
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 
Locust a 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 flexor uitguium. 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, cbnjungentes superiores, s. 
dorsales}, are divided into several contiguous bellies, which run flatly 
from the metanoturn 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. .). 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, &.), 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 an( l 
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 flat 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 
back 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 win^rs, during; the several moult- 

O ' O 

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 Hymcnoplera, is very different; the larvae of the 
Coleuptera display much more conformity with that of the developed 
beetle, for they are of all the most perfect larvte, and in the structure 
of their feet agree very much with their perfected state. 

The most conformable muscular distribution in all larvee 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- 
dorsales. 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-)-. 

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, Traitd Anatomiquc, &c. a la Haye, 1760, 4to. PI. yi. vii. & viii. 

f 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 nervxms 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 coxse, 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- 



2G8 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. f Tbi<1 - pl - VI - D - D - 



THE ORGANS OF SKNSATION. 2G9 

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 (iieurilemu) , 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 OF SENSATION. 271 

ray observations in the caterpillar of Noctua 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 resophagus 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. 

1 This reminds us of the red nervous points in many of the lower animals, namely, the 
Infusoria, especially the Rotatoria. Ehrenherg, 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. 



'27'2 ANATOMY. 

I. THE BRAIN. 
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 (PL XXXI. and XXXII. A, A, A,) is a nervous cord 
of a yellowish white colour, lying transversely across the oesophagus, 

* J. Miiller asserts of Phasma gigas, that the brain lies beneath the oesophagus (Nova 
AcUe, 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 resophagus. 



THE CRREBRU.M. 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 genei'al 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 antennatis). 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 Dylicus 
it originates with a thin base, then suddenly distends, and afterwards 
runs as a straight cylinder to the orbit ; in Melohmtha it is not per- 
ceptibly distinguished from the hemisphere of the brain, nor is its dis- 

T 



274 ANATOMY. 

tension towards the orbit very distinct ; in Locust a 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 opticisecundariij, 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- 
mata spring from the lappet-shaped distension of the cerebrum, some- 
times separated (Calo.ioma, 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 

' Treviv.'imis, Biologic, vol. v. PI. II. f. 1 .3. r, r. 



THE CEREBELLUM. 27> 

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 haxistellate 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 migraforius, 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 ( PL XXXI. 
f. 7. d, d. and d*, d*.}. 

185. 

THE CEREBELLUM. 

The cerebellum (PL 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 fiexor 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 



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 (Melolontha, 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 conies 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 (PL XXXI. and XXXII./,/. and 
f *,/*) originate sometimes in front (Calosoma, PI. XXXII. f. 1.), 

sometimes behind (Melolontha and Gryllus, PL XXXI. f. 4. and 7-)> 
the nerves of the mandibles from the cerebellum, and run closely to these 
to the maxillae, 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, PL 

XXXII. f. 1. f, f. and f*, /'*.) 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 (PL 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, PL 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 Locuxla (the same, f. 7-) 5 which, notwithstanding that 



THE VENTRAL CORD. 2/7 

it is furnished with a large fleshy tongue, I could find 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 maxilla 1 , 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. venlralis) 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, Avhich 
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 herf 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 Noclua verbasci,) 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. 

O 

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 si/cophanta, and shall therefore particularly describe. 
The first pair of these auxiliary connecting filaments originates from 
the posterior portion of the cerebellum (PI. XXXII. 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, &.) 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 
diiferences 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, COUI). 279 

larvae of the Diptera, Hymenoptera, and Coleoplera. Among the 
larvae of the Diplera 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 
Rosel 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 Natura-, \>. 166. a. f Ibid. PI. XL. f. 5. 

Ibid. PI. XXVI11. 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 Stratlomys, 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 sycophant a 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 

* Lj-onct. ri. ix. 1. 1. :, -i, -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 (Meloe, Lytta), the capricorns, and pro- 
bably also in the Chrysomela ; in the fat footless larvae of the Curculiox 
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, Meloe *. 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, Libellula, and many families of the Cole- 
optera, 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 Ratztburg, Araicitliicrc, vol. ii. part iv. PI. XVII. t'. '1. 



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 (Locusta viridissima, Termes fatalis, Calli- 
chroma moschaium). 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 
Locustce, Termites, and Libellula:, 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 CORI). 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 Coleoptera 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 cquina of the superior animals, distribute 
themselves to the internal sexual organs and to the colon. In Carabus, 
Hydrophilus, 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 
Avhich have but two separated ganglia in the thorax. In the Coleoptera 
the large family of the Lamcllicornia 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, PL IX. 



284 ANATOMY. 

wise sends off many branches 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 line 
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 
(PI. 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 Lepidopiera 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 Pkilantkus piclus, 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 Lcpidoplcra from the growing together of 
most approximate ones, which takes place by degrees during the pupa 



THE VENTRAL COUD. 28:> 

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 
ineso- 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 Hymenoplera 
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 

A o o o o 

(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 

Biologic, vol. v. PI. I. II. and III. 



2fi6 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 lenax 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- 
cornis*), and by Lyonet in the larva of the large Cossus^. 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. 
Miiller claims the greatest merit for giving the details of this system 
in a distinct treatise J, 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 Mailer, 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 sympathic 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., torn. xiv. part i. p. 73, &c. 

J. J. Brandt, Beobachtungen iiber die Systeme der Eingeweidcnerven. Isis. 1831, 
p. 2003. 



THE SYMPATHIC SYSTEM. 2c./ 

which originates oft 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 Libellulae. 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 antennae. 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.). In 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 Coleoplera, 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 (LepidopteraJ 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, 6*. &*.) 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 Durkheim, 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 Gryllifs. In Gryllus migra- 
torins (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* e?*), which then sends off a long, rather strong filament. 
This filament runs down by the side of the oasophagus, 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 M tiller *, 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 Achela Gryllotalpa t, 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. Blalta 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 SENSKS. 
192. 

OF all the several organs of the senses, the eye alone possesses a 
superior development : nose and ear 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. f Ib. f, 2. 

u 



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 Joh. Muller $. 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 Duges, 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. 

. 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). 

6. TheDicfyoioptera, Thysanoura (with the exception of Machilia 
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 bei den 
Insekten. Getting. 1798. 8vo. 

t" M6m. sur les Yeux composes, et les Yeux liss^s des Insectes. Montp. 1813. 8vo. 

\ Zur Vergleichende Physiologic des Gesichtssinnes. Leip. 1826. 8vo., and Suppt. to 
it, in Meckel's Archiv. 1828. 

Annales des Sc. Nat. xx. 341. 6. || Ih. torn, xviii. p. 463. 



THE ORGANS OP THE SENSES. 291 

1 . Ortkoptera collectively, without Forficula. 

2. Dictyotoptera, Libellula, and Ephemera, have three simple 
eyes, Termes but two. 

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, Plata, but two. The water bugs, as Nepa, 
Ranatra, Naucoris, Nolonecta, 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 Noctuce (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 Onthophagus, 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, Forficula, 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 fits 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-. 

u2 



292 ANATOMY. 

spending 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. 
Regaining 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 

LibeUula .... 12,544 

Papilio 17,355 

Sphinx Convolvulus . 1,300 

Cossus ligniperda . . 11,300 

(Estrns 7,000 

Liparis Mori . . . b',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. Mailer * 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 facet, 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 

* 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 Noctuee, Joh. Miiller found the proportions 
of length to the breadth of the base to be as 5 to 1. In CEschna, 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 MUller 
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 choroidea 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 
Avith 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 Poniia 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 hicro- 
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. M filler's 
admirable treatise upon this subject, and that here merely the most 
interesting portion of his results are stated. The subsequent labours 
of Straus Durkheim f and Duges 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. Muller 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 

* Muller, p. 355. f Considerations General, &c., p. 40S 

+ Annalen clu Wetterau. Gesell. f. d. Ges. Naturk. Vol. i. Pt. 2. 180!>. 
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 antenna?, 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. CarusJ, Straus Durkheim , 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 Ib. p. 24. J Zootomie, p. 65. 

Consid. Generates, p. 415, &c. 

|| It was not unpleasing to me to find in the recent edition of Okeu'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 
Orthpptera, 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 vomit oria; 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 horny 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 Coleoptera, 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 Inscctis. Aboa;, 1792. J Sdielvcr, p. 46.. 

Reil's Arcliiv. 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*, 
who 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 Durkheim 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 o the superior rnollusca, 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. 

1 Vermischte Schriften. Vol. ii. p. 146. t Considerations, p. 421. 

The -whales want the auxiliary cavities of the nose, which secrete the fluid, because, 
living in \vater, they do not require them. See Rudolphi Physiol. Vol. ii. PL 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, Libellulee, 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 Libellulee 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 Durkheim * 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 Avhose feet have soft fleshy balls (Xenos, T/trips, 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 
Ruminantia, 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. -i'27. 



THE ORGANS OP 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, Rbsel, 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 
(Eristali.v 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 the 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 connexion 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 doable generation (generatio cequalis), or pro- 
pagation (generatio propagaliva). 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- 



OP GENERATION. 307 

pagatiou 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 Iftiand, 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. Fourniert 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 Phtlnriasi. Bonn. 1824, fig. 4. 4to. 
)- Dirt. Medirale, Art. 



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 Phthiridsis, 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 P/tthiriasis, 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. Aiiim , Lib. v. cap. 31. 



OF GENERATION. 309 

ings, out of which they came when opened. These creatures were 
doubtlessly no lice, but Acarinte, 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 exulcerans), 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. Encyclopedie 
of Ersch and Gruber, torn i., which are written by Nitzsch, doubt- 
lessly the best acquainted of anybody with parasitic insects and the 
Arachnidce. 

The Acari stand in the same degree of relation to the Arachnides 
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 nocks 
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 ivhich 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 arachnids; (Acarinee) originate precisely in the 
same manner. In the pustules of the itch they are developed only so lonj; 
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 Dianl/ti 
continue to propagate for four years without the single impregnation of 
a femak 1 by a male, but they continued to produce young ones which 



OP GENERATION. 31 1 

were all of the female sex*. But, according to Bonnet t and Do 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 j 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. Schiffermuller subsequently observed the 
same ||, as well as Pallas % who described the species upon which he 
made his observations as Phalcena yylophthorum. 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 ft, who, among other instances of the kind, mentions one of 
a cased caterpillar, in Kiihner |J 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.] 4. t Insectologie, torn. i. 

J Contemplations de la Nature, torn. i. 

M(5moires, edit, in 8vo, torn. iii. part i. p. 194. 

|| Verzerchniss der Schmet. der Wiener Gegend. 4to, 17G6, p. 288. 

If Nova Acta, toin. iii. (1767) p. 430. 

* Schmettcrlinge von Europa, vol. iii. p. 178. 
ff Me'm. de I'Aca.'i. Roy.de Berlin, 1772, p. 24. 
U 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 Bombycida, 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 RhypJms, 
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. (Bomlyx 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 seclies), which his friend, Professor Easier, had seen. He 
reared the caterpillar, it changed into a pupa, the imago came forth, 
Avhich 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 | has observed the same spontaneous 
development in Sphinx Ligustri, Suckow , in Gastrophaga Pint, O., 
and my friend, Dr. Al. V. Nordmann, recently in Smcrinthus Populi. 
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 Heusiuger's Zeitschr., f. d. Org. Phys. vol. ii. p. 264. 

t Miscell. Acad. Nat, Cur. an. 9 et 10. D. 3. obs. 11. p. 2U. 

Venn. Scbiift, vol. iv. p. 106. In Heusinger, 263. 

II d'eineinnutzigc Arbeiten tier Sa'chsis, Biencngesellscb, vol. i. part i. p. 39. 

f 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 hermaphroditisrn among them. 
Perfect hermaphrodites among animals are found only in the tape- 
worms, the Trematodes, many Annulala (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 
SchiifFer in a separate treatise t- It was an hermaphrodite Liparis 
dispar, O., the right side of which was male and the left female. Then 
Scopoli 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 antenna, 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 Crattegi, 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 Rudolph! iVber Zvvitterbildung in the Abhandlungen der Konigl. Academic 
zu Berlin. Physkalischeiklasse, 1828, p. 50. 

f- Der wunderbare und vielleicht in der natur noch nie erschienene Eulenzwitter. 
Regensb. 1761, 4to. 

Introductio ad Hist. Nat. Prag, 1777, 8vo. p. 41(j. 

Beobachtungen an einer neuentdeckten Zwitterphalane (Bombyx Cratcegi*). Erlangen, 
1778, 4to. Schinetterlinge, vol. iii. p. 233. PI. XLV. f. 16. 

|| Rozier, Obs. dc Phys. torn. xxvi. p. 270. 

ll Naturforscher St. .\ii. p. 72. PI. II. f. H 



314 



PHYSIOLOGY. 



Carpini, the left wing and antenna of which Avas 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 Avhich 
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 Linnscan Society, sent 
an hermaphrodite to MacLeay, which on the right side was male, and 
/'. 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. 

Lyc&na 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. 

I.yccena 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 np (indicating the pre- 

* Papillons d'Europc, torn. iii. p. 123. PI. CXX1I. n. 114. 

t Fauna Boica, vol. ii. part i. p. 102. 

Naturgcscliichte der Schmetterlinge von Europa, torn. iv. p. 185. &c. 

Trans, of the Linusean Soc., torn, xiv.p. 584. 



OP GENERATION. 315 

sence of the right ovarium. Described by Germar, and caught near 
Dresden "". 

Vanessa 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 t. 

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 antenna? and wings 
female, left male ; body of the form of the male, but coloured like the 
female ; a distinct separation not observable. Rudolphi, as above. 

Endromis versicolora. Right male, left female ; abdomen female, 
but upon the right side coloured as in the male. Ochs. 

Liparis 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. 

Gastropliaga querdfolia. 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 

* Medici's Arc hi v. fur Physiologic. 11119, torn. v. p. 365 8. 

f Ibid. I Ahrcu's Fauna Insect. Europ., fast, i. Pl.X.X, 



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. 

Gostrophaga 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 Coleoptera, in Melolontha vulgarly, 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. | 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 
Aving 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. 

O O <-2 O 

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 Gcsellsch Naturf. Freundc zu Berlin, 
f McekiTs Archiv, vol. 5. p. 366. J 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 chieHy as in the male, the 
left as in the female. Ochs. 

Gastrophaga quercus. Two individuals: 1st, body and antennae 
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 Hnd 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 



31o 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 Bo-mbyx really laid eggs, it did so like all the female 
Bombi/ces, 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 investigate 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 

lew 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 chieHy 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 King f 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 Coleoptera, 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 Cicinddce, 
Caraludea, Dylici, the males have distended anterior tarsi. The 
number of these distended joints varies in the several families and 
genera. In Cicindcla the three first joints only of the anterior legs 
are distended. In the Carabodca 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 dcr Hallisch. Naturf. Gesellscli. vol.i. PL VI. 

f Magaz. der Gesellsch. Naturf. Freumle zu Berlin, 1807, p. G5, and 1808. ;j. 48. 



320 PHYSIOLOGY. 

as Amara, the Zabrodea, Feronia;, 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 FJaphrus, Blethisa, &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, Pcecili, 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 
cnnsobrinus*. 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 copula 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 Schvift. 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. Schonh. Syn. Ins. 
$ Hydr. nigrolineatus. Kunz., ib. p. 61. 1. 

Hyph. parallelogrammus. Oyll.,Ins. Sues., torn. iv. p. 08!). 13 14. 
Hyph. nigrolineatus. Gyll. Ins. Sue?., torn. iii. add. p. 638. 
Dyticus lineatus. Marsh., En torn. Britt. i. 426. 35. 
t Ibid, Cl. 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 
Staphylini, 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 Stapli. 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- 
porus rufipes the excision of the ventral plate is so deep that it has 
the appearance of being bilobate, and in Lathrobiwn 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 Dermextodea 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 Scarabeei (for example, Typheeus), 
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 lamellge 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 lonei- 



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 Buprestis the male has again an arched 
excision in its last ventral plate ; in the Elaters 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 Plilinus and Dor- 
catoma ; and very decided differences are exhibited in the male 
winged Lampyri,ihe 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, Brentus, 
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. 1'2. 



OP GENERATION. 323 

Lcpidoptera, for instance, in some of the Geometers (brumata, 
namely, and many others), and in the genus Psyche, Latr. The 
males of the Bombyccs 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 Libellula*, 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 proboscidcus, 
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 Cullces 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 Tipulce 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., (Hexa- 
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 (Teltigonia, 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,o.nA 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 Scolite, the females have generally 
brighter markings than the males, for example, Scolia horlornm, in 
which the head of the female is of a reddish yellow; Fabricius conse- 
quently considered it a distinct species, and called it Sc.flavifrons. 
In Tiphiafemorata 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. Ercchlhcu.s male, and Pap. JEgeus female, described by 



OK 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 (LycoziKB) 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, arid consists in the sexual 
union, is called copulation (cojmla). 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- 



326 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 
LibellulfB 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 inlluentially 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 rind them thus occupied during the 



OF GENERATION. 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, Ephemera, 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 Diplera. Whereas, 
some Hymenoptera, 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 



328 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 Jassiis 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, cohsequently, 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 Carabodea, 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, Dolichopus, Tipula, 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. 329 

copulation. In Melolonlha, 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 Avhen, 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-much-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 liis Lcttrc sur la Generation des Insectcs, in the Annalcs des Scicnc. Natur. 
T. ii. p. 281. 



330 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 SuckoAv *, 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 f> in the Cercarice which inhabit 
fresh-water muscles, but, indeed, after these animalculae have quitted 
the body of the muscle for the water. These animalcule (Sper- 
matozoa, according to De Bar) 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 iu 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, 

* Heusingcr Zeitschr. f. d. Org. Phys. vol. ii. p. 261. 
f Bi-itrng zur Infusorienkundc. Halle. 1817. 8vo. 



OF GENERATION. 331 

in Mclolontha and in Mcloe, 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 |., 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 Miiller has 
informed us, the development of the germen already commences there. 

* Lectures 011 Comparative Anatomy, vol. iii. p. 370. 

J- Versuch liber die Erzeugung. PI. I. p. 245, &c. 

t Opera Omnia. vol. ii. De Bombycc. p. 41. (Lttgd. Batav. 1687. 4to.) 

Naturforschcr. 4 St. p. 115, &c. 

|| Heusingcr Zeitschr. f. d. Org. Pbys. vol. ii. p. 262. 



332 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 effected, 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 clone 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 ( PL 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. 

* Physiologic, 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. Muller * 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. Muller 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 Mecke!' s Arcliiv. fur Anat. uml Physiol. 1828. pp. 26 and 27. 



OF 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, Lytia 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 Cheiuische Schrift, vol. ii. p. 112. 
Z 



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, arid 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. Physiologisehen Untersuchungen der Insekten uml Krustcn- 
thiere, vol. i. part i. Heidelb. 1818. 4to. 

f- See PfafF and Friedlandcr franzosische Annalcn, part iv. p. 48, &r. 



OF GENERATION. 

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 tho 
circumference of the entire yolk. The second external membrane lying 
over the amnion (the same, b, 6,) 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 (PI. 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 (Sarcophagte) 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 ^ 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&noires, &c., vol. iv. part ii. p. 153. PI. XXIV. f. 1. Edit, in 12mo. 

f Ib. vol. vi. p. 31. PI. III. f. 518. 

+ Ib. vol. iv. partii. p 168. PI. XXIX. f. 1015. 

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., (Tineaprolclclla,iim.), 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. dcr Gcsellsch Naturf. Frcundc zu Berlin, (>. B. s. 131. 
f Author's MS. addition. 



OF GENERATION. 343 

vulgarin} 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 
Nocluce ; 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 Coleoplera ; in 
these the average is fifty : many, as the Chrysomefce, lay more (viz., 
Chrysomelce polygon?) ; others, for example, Meloe, Lyltu, which have 
baccate ovaries, also lay many eggs, namely, from 600 to 800. The 
burying beetle (Necrophorus 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 at one time. The Diptera pupipara, 
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 Aphides, 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 



OK 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 
Acalephte, 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 however 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 Fertebrnta. 

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, 



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, Acaleplice, 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 branchiae. 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 Avould take place 
everywhere. We also absolutely find that animals whose body is 



OF DIGESTION. 34/ 

traversed throughout by trachea?, 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 organisahle 
(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 OP 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 Coleoptcra, Orthoptera, Dic- 
iyoloptera, 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 

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 Gallime, 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 maxilla;. In the ontkophagous Pctalocera 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, Viburni, &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 larvEe 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 Libellulee 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 maxillae armed with long teeth. It is distinctly seen how 



OF DIGRSTION. 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 Dictyotoptera 
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. 
. Merely in the mouth. Libellulce. 

b. Less in the mouth, but more in the proventriculus. Cara- 

bodea, water beetles, and StaphylinL 

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. Ontho- 

p/iagous Petalocera, Pcltodea, Capricorns. 

b. They are lapped up by the pencillate maxillae and sucked 

out in the mouth. Lucani, Tenthrcdonodea, 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 (c, f.), at the base of these maxilla?, 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.^ /!). 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 Avith the perfect insect only 
upon flowers, particularly upon the umbelliferce, .syttgcnistce, nymphece, 
and similar plants, which grow in the vicinity of water, whereas the larvaa 
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 suckina; stomach, 

O 

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 t 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 Diciyotoptera, as Hemcrobius, 
Myrmecoleon, Ascalaphns, 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 arc pro- 

Verdauungswerkx. PI. XVI. f. "2. f Vrnnisclite Sclirilieii, vol. ii. p. 15(1. &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 \vell 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- 
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 Paraglossa, PL VI. f. 7- a, ) ; the aperture of the 

* Vermischte Schriften, vol. ii. p. 134. 

t Opera Omnia, Lugd. Bat. 1687, torn. ii. p. 44. 

J Biblia Naturae, p. 138. a. Vergl. Anat. vol. iv. p. .92. 

|| Abh'and. uber die Verdauungswerk/. p. 1 1 . 



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 Lepidoplera 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 Lepidoptern, 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 Diplera 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, 



OP 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 Cicindela;, Carabodea, 
Hydrocanihari, 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 (T)ermestoAed) 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 Pdalocera, 



OP DIGESTION. 355 

viz., Copris, Onthophagus, Ateuchus, Gymnopleurus, Onitis, 
Aphodius, and many others ; then the Hislerodea, many 
Staphylini, the genus Spheridium, as well as the larvae of 
innumerable Culiccs and flies. But as these substances have 
considerable affinity with carrion, and the onthophagous 
insects with the Peltodea, many species of botli 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 Lucanus and Oryctes ; others devour the corrupt 
substances which are deposited beneath the bark of dead 
trees, for example, Hypophleus, Engis, Ditoma, Colydium, 
Hhyzophagus, 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 Melolontha, 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 

11 Mem. torn, v. p. 1. pages 14, 15, edit, in 12mo. 
A A 2 



350 PHYSIOLOGY. 

upon seeds. To these the larvae of the Curculios especially 
have recourse. The Apion Jrumentarum 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 (Estrns 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 Coleoptera, 
Drilus, which is parasitic upon snails, and Symbius, Sund., 
whose larva feeds upon cockroaches. The parasitic state of 
the larva of Melo'e 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- 



OF DIGESTION. 35J 

fore always remain apterous, whereas those of insects and 
mollusca 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 Hippobosca 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 Lepidoptera, whereas 
in the spiders it is the usual and most common form. 

6. 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 flies, for instance, Musca Caesar, Scato- 
phaga pulris, Scybalaria, &c., and are even lapped up by the 
Coleopiera, 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 Aphidce, 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 
wasps, 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, Coccinellw, &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 Mycetophthires 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 del 1 Nalur. torn. 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 Notonectce, 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 andSpence 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 Simulite, 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 Spcncc, 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, 
Gryl/i, 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 Lcpidoptera, 
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 



3U2 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 Lcpidoptera ; 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- 
plera 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 Hemiplera, 
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 Dylici, 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 proventriculns, 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 
larvse ; 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 Untei'suchungcn uber den Thieriachen Haushiilt tier Insckteu. 
Tubing. 11)17. Hvo. 



364 PHYSIOLOGY. 

a thick pappy mass, which melts by the addition of acid, and on the 
applicatipn 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 f. This last opinion is doubtlessly the 
most correct, for the Avhole 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 proventricnlus to the muscular stomach 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. 

j- The true duodenum of insects is the villose stomach, or, where this is wanting, the 
lonj 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 proventriculus, 
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 
Deilephila 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 the chyme. But if the period of fasting he 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 voracity 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, nuist 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 uber die Verdauungsgesch, p, 36. Reaumur, M6m.de 1'Acad. 
des Sc. de Paris, A. 1752, p. 472. 



OF DIGESTION. 367 

efforts was thrown 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, Libdhdce, 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 Hymcnoptera 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 Coleoptera 



368 PHYSIOLOGY. 

we find a family which agrees entirely with the Lepidoplera 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 
by 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, proventriculus 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 PHYSIOI-OGY. 

nutrimental canal throughout the animal kingdom. They thus repre- 
sent in their crop and proventriculus 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 ; audjastly 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 O7ily. 
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, Posselt, 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 Tiedcmann and Gmelin upon digestion. 



OP DIGESTION. 371 

3. That at the spot where they empty themselves into the intestine 
there is frequently a bladder-shaped distension, a kind of -/all 
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. Miiller, 
and by the altered views of Meckel * and Treviranus f 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 , 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. Wur/er found also 
urate of ammonia, and both phosphate and carbonate of lime, which 
Brugnatelli || and John equally found also in the excrement of 
Lepidoplera 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 Arcliiv.,iv. p. 213. || Ib., 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 Avith 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. Biologic, torn. iv. p. 4'20. 
f 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 Rudolph! * 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, Dytici, and Slaphylini, distinct urinary 
organs have been found ( J13), 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. Muller J, 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, Leptis, 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 

* Physiologic, vol. ii. part ii. p. 145, note 1. 

f Guiel. Handb. d. Theor. Chcmie, vol. ii. part ii. i>. 1473 

J De Gland, secern, struct, pen., p. <J!>. 



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 casca of birds. These organs, which 
Cams * 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 

' Zootoinic, p. 388. 



OP DIGESTION. 375 

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. Muller 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 Dylici. 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 many 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 Arachnids 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 pressing the vessels, 



3/6 FHYSIOLOGF. 

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 
npon 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 Melolonlha vn/garis, namely, 
Ramdohrt 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 oflf ramose appendages, whereas posteriorly 
they have none. That the biliary vessels in many cases, for example, 

* P. 270. t Abhand. uber die Verdauungsorgane, PI. XVIII. f. 1. 

J Annales dcs Sciences Natur. t. iii. p. 234, PL XIV. f. 4. 
i In Heusinger Zeitschrift. f. d. o. Phy. vol. iii. Pt. I. PI. III. 



OF 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). 
Joli. M tiller 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 

/ 4? 

DC Glatulul sec. 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 Dytici and Peltodea, particularly as it is not only longer here than 
the duodenum, but even several times its length, for example in Necro- 
phorus. 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 larvee, 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. 370 

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 bitrsa Fabricn 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 thud, 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 Phryganea and in the Antlion, &c., which also devour animal 
matter, it jilso contains ammonia * and a material allied to the horny 

* Gmelin's Chcmic, vol. ii. Pt. '2, p. 1-I7.V 



OF DIGESTION. 381 

substance, the presence of which is to be deduced from the variety of 
their 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, Spkeges, 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 setae, 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 Cnrabodea 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 rne 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 Dijfici, 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, which chemists designate by the name 
of cantharis camphor t, 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 
(Scarabeufi^), and in some C/iri/somcke 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 Mdoe 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 fur Physiologic, vol. iii. p. 62., upon these 
wax-preparing 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 Mackaon 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 Dipt era we find 
individual instances of a presence of peculiar secretions, for example, 
in Ccenomya ferrvginca, 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, notacantha), 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. Untcrsuch., 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 t- 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 Hymenoptcra 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. -f- Ibid. p. 39. 



OP 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 Locusta mridissima 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 o? 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 

o o 

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 Biologic, vol. 
iv. p. 161. 

t Disquisit. Physiol. circa Respirat. Insectoram et Vermium, p. 27. 
I Ibid. p. 46. Ibid. p. 66. 

c c 2 



388 PHYSIOLOGY. 

were in vain, for its clipped wings made flight impossible. 
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 LibeHula 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 verv moment, however, that 
the beetle flies off, it compresses its xvhole 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 5 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 

* Beitrage zur Anatomic der Pflanzen, p. 309. 

t Biologic, vol. iv. p. 151. 

t 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 modems, 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 Ugniperda 
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 diiferent 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 Hi/drophilux. 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, 

Rcil's Archiv. fur Physiologic, t. .\. p. 440. 



OF 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 whirl wig, 
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 
tracheae, 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 ; they are also found in the majority 
of the larvae of the Diptera 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 
larvaa of Msclma 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 larvse 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 larvse 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 
Diplera. 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 larvee. 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 



OP 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 mimites') and 

quantity (100 grains). 



Name of the Insect. 


State of the 
Thevmora. 
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- 


22 


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 


15 


23,7 


1 70 






c 


16 


10,0 


I ) t V 

72 






tcrrc^tri^ in the c un 


14 23 


11,0 


^i ' * 
1 74 






l-^|]cpo]'iim - . 


17 


46,2 


J.J fl ~X 

0,64 


0,82 


0,18 


Ei-istalis nemorum (Melg.) 


1616,5 


7,4 


J" 

0,50 


W} VTAri 

0,80 


0,30 


Pontia Brassicse (^Cater- 












pillar) 


1413 


2Q 
,o 


0,16 


0,28 


0,12 


Rapse A. after 












starving 28 hours 


15 


8,3 


0,72 


2,26 


1,54 


B on dyin^r 


13,517 


2,0 


0,20 


0,37 






Vanessa Atalanta A. after 












3 days starving - - 


1328 


27,0 


2,65 (?) 


2,35 




B the '"line 












and weakened by the 












preceding experiment - 


15 


105,0 


1,50 


2,35 




Libellula depressa A. 


1716,5 


6,2 


0,37 


0,74 


0,37 


jj 


Ifi K. 14. 


7,5 


0,33 


0,93 


0,60 






Cetonia aurata (larva) 


17 


6,1 


0,04 


0,06 


0,02 


4 


16,5 


2,9 


0,21 








B after 












days starving 


13,514,5 


1,5 


0,06 


0,07 




Melolontha horticola 


1315 


2,0 


0,07 


0,17 


0,10 


Feronia nigra 


1115 


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 with 
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, 4i, 98. 



OF RESPIRATION. 401 

object 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 first 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 MaraldiJ, Reaumur, and Huber. 
Reaumur observed a thermometer standing at 6| external tem- 
perature rise in the hive to + 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 + 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 organisclie Leben, t. i. p. 413, &c. 

\- Biblia Naturae, p. 161. 

J Mein. cle 1' Acad. des Sc. de Paris, 1714, Ed. d' Ainst., p. 420. 

Nouvelles Observ. stir les Abeilles, t. ii. p. 338, &c. 

!| Iileen zu einer Zoochemie, vol. i. p. 9'2. 



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 

* Compare Hausmann de Aniin. Ex. Respirat., pp. 68, &c. 

f- 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 PHVSIOLOGY. 

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 t. 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 J. 
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 ernes Einfacben vom Herzen aus beschleunigten Blutlaufes in den 
I.arven netzfliiglicher Insekten. Leipz. 1827. 4to. 

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. With 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 iiber das RiickengcfiibZ der Insektcn. Mcii-b. 1823, 8vo. 



406 PHYSIOLOGY. 

Accor,i' n g 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 
( Gastropacka pint) 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 Dictyolopfera, 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. tiber Insekten und Krustenthiere, p. 37. 
f Cams in the Nova Acta 1'bys. Med. vol. xv. Pt. 2, p. 8. 



X 

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 Agrlons 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. hitea 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 ckrysops, 
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 larvse 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, Cams 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 
solstilialis and in a Dijticus ; 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 Orthopiera, on the contrary, he vainly 
sought it in the wings, but Ehrenberg, according to the communication 
of A. v. Humboidt, has seen a motion of the juices in a Mantis t. 
The transparent wings of the Dic/yotoptera and Ncuroptera have 
likewise here and there exhibited a motion of the juices, as well as the 
wings of Libtllula depressa, Ephemera lutea, E. marginata, Hemerobius 
chrysops, but most distinctly in Semblis bilineala and in the antennae 
of Semblis viridifi. 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 j but Carus thinks he may 

* Nova Acta Soc. n. c. C. L. vol. xv. Pt. 2, p. 1, &c. 

f Bericht iiber 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 was cut off. 



CIRCULATION OF THE BLOOD. 409 

adopt a motion of the juices in the germ en 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 upt, 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 Phvs. Med. vol. xv. Pt. 2, }>. 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 by 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 bronchise 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 marginalia, Copris lunar is, Pkilanthus 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. 



412 



PHYSIOLOGY. 



Jurine's * and Chabrier's f 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 tracheag 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) J. 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 Avings, 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 Avhole body that 
it has no blood-vessel excepting the large dorsal vessel. Indeed 
Joh. Miiller considers k 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. Mth. de Classer les Hymenop. Geneve, 1807. 4to. p. 48. 
f Essai sur le Vol des Insectes. Par. 1822. 4to. p. 42. 
: Natur. Philosophic, 2nd Ed. p. 418. No. 3337. 
Essai sur le Vol, &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 ai*rive 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. 



THTRD 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. 41 ~) 

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 (Arihrozoa). 

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 animalia 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 : 



410 PHYSIOLOGY. 

i. Group - GASTROZOA. The following classes belong here : 

1. Infusoria polygastrica. Ehrenb. 2. Polypina sive 
Corallina. 3. Medusina. 4. Echinodermata. 
5. Mollusca. Cuv. 
n. Group ARTHROZOA. Here belong the classes : 

6. Endozoa. Annulata. 7- Rotatoria. Crustacea. 

8. Myriapoda. Arachnodea. 9. Insecta. 
ill. Group OSTEOZOA : 

10. Pisces. 11. Amphibia. 12. Aves. 13. Mammalia. 

246. 

The forms of the thus discovered three chief groups of the animal 
kino-dom 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. 

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 Arlhrozoa. 

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 (Ififusoria rolatoria, 

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 Araclmodea (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-Arlhrozoa 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, Lumbricini sive Chcetopodes'), and, lastly, as 
short pedal warts with booklets (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