silk-gland of a saw-fly larva; _n_, nucleus; _i.d_, canals; _d.s_,
cavity.—After Gilson.
]
Histologically the silk-glands are composed of three layers,—the outer,
or _tunica propria_ (Fig 337); the inner, the _tunica intima_; the
middle layer being composed of extraordinarily large epithelial cells
which can be seen with the naked eye, and are also remarkable for the
branched shape of the nuclei (_a_, _b_, _c_, 337), the branches being
more or less lobed, and the larger the cells the more numerous are the
branches of the nucleus. Gilson[53] finds that those of Trichoptera,
Lepidoptera, Diptera, and Hymenoptera ordinarily consist of a small
number of cells; and it is quite common, he says, to find only two cells
in a transverse section (Fig. 338, _A_). In the Tenthredinidæ, however,
“the organ still consists of a tube, the wall of which is composed of
flat cells, but in addition to that, two series of spheroidal cells are
attached to the sides. Each of these cells contains a system of tiny
canals running through their cytoplasm (_B_, _i. d_). These cells are
the secreting elements; they continually cast the silk substance into
the tube.” A peculiarity of the _tunica intima_ is its distinct
transverse striation.
[Illustration:
FIG. 339.—Branching nucleus of spinning gland of Pieris larva.—After
Korschelt, from Wilson.
]
[Illustration:
FIG. 340.—Filippi’s glands (_G_) isolated and seen from above: _e_,
_e_, its lobules; _d_, its excretory canal; _E_, silk-duct; _C_,
common canal; _c_, upper spinning muscle; _b_, lower muscle; _a_,
lateral muscle; _T_, spinneret.—After Blanc.
]
The lining of the glands and of their common duct is moulted when the
caterpillar casts its skin, and this, as well as the mode of
development, shows that the glands are invaginations of the ectoderm.
Gilson finds that the silk-glands and silk-apparatus of Trichoptera are
very similar to those of caterpillars, and that the silk is formed in
the same way.
=Appendages of the silk-gland (Filippi’s glands).=—In most larvæ there
is either a single or a pair of secondary glands which open into the
spinning glands near their anterior end. They are outgrowths of the
gland provided with peculiarly modified excretory cells or evaginations
of the entire glandular epithelium. Those of _Bombyx mori_ (Fig. 340)
are very well developed, and, according to Blanc, form two whitish,
lobulated masses in the labium on each side of the common duct of the
spinning gland. Externally they appear to be acinose; but their
structure, as described by Blanc and by Gilson, is very peculiar. Helm
thinks, with Cornalia, that the function of these glands is to secrete
the adhesive fluid which unites the silk threads, and also to make the
silk more adhesive in the process of spinning, but Blanc states that
this is done before the thread passes into the common excretory tubes,
and he is inclined to think that the secretion serves to lubricate the
spinneret, and thus to facilitate the passage of the thread. On the
other hand, in certain caterpillars these glands are situated quite far
from the spinning apparatus.
The silk-glands in the pupa state undergo a process of degeneration,
and finally completely disappear. They are specific larval organs
evolved in adaptation to the necessity of the insect’s being
protected during its pupal life by a cocoon. (Helm.)
Morphologically the silk-glands are by Lang regarded as modified
coxal glands, and homologues of the setiparous parapodial glands of
chætopod worms, the coxal glands of Peripatus, and the spinning
glands of spiders.
In Scolopendrella, spinning glands are situated in the two last
segments of the body, opening out at the end of the cercopods (Fig.
15, _s.gl_), and the larvæ of the true Neuroptera (Chrysopa,
Myrmeleon, etc.) which spin cocoons, have spinning glands opening
into the rectum. The silk forming the cocoon of the ant-lion, as
Siebold and the older observers have stated, is secreted by the
walls of the rectal or anal sac. Siebold (Anatomy of the
Invertebrates, p. 445) states that in the larva of Myrmeleon, the
silk-apparatus is very remarkable, “for the rectum itself is changed
into a large sac and secretes this substance which escapes through
an articulated spinneret projecting from the opening of the
anus”[54] (Fig. 307, _e_). The larvæ of the Mycetophilidæ have
spinning glands at the hinder end of the body, as also the imago of
the female of the tineid moth Euplocamus. (Kennel.) The larvæ of
ichneumons, wasps, bees, of Cecidomyia, and other Diptera, spin
silken cocoons, but their glands have not yet been examined.
It should also be observed that during the process of pupation the
larvæ of butterflies, of certain flies (Syrphus), and beetles
(Coccinellidæ and some Chrysomelidæ) attach themselves by silk spun
from the anus, so that the pupa is suspended by its tail; such
glands are probably homogenetic with the coxal glands.
The silk in its fluid or soft state is mucilaginous, and according
to Mulder, in the silkworm consists of the following substances,
varying somewhat in their relative proportions by weight:
Silk-fibre material 53.67
Glue (Leim) 20.66
Protoplasm 24.43
Wax 1.39
Coloring matter 0.05
Fat and resin 0.10
LITERATURE ON THE SPINNING GLANDS
=Helm, E.= Anatomische und histiologische Darstellung der
Spinndrüsen der Schmetterlingsraupen. (Zeitschr. f. wissens. Zool.,
xxvi, 1876, pp. 434–469, 2 Taf.)
=Lidth de Jeude, Th. W. van.= Zur Anatomie und Physiologie der
Spinndrüsen der Seidenraupe. (Zool. Anzeiger, 1878, pp. 100–102.)
=Engelmann, W.= Zur Anatomie und Physiologie der Spinndrüsen der
Seidenraupe. (Onderz. Phys. Lab. Utrecht, iii, 1880, pp. 115–119.)
=Joseph, G.= Vorläufige Mitteilung über Innervation und Entwickelung
der Spinnorgane bei Insekten. (Zool. Anzeiger, 1880, pp. 326–328.)
=Poletajew, N.= Ueber die Spinndrüsen der Blattwespen. (Zool.
Anzeiger, 1885, pp. 22–23.)
=Meinert, Fr.= Contribution à l’anatomie des fourmilions. (Overs.
Danske Vidensk. Selsk. Forh. Kjöbenhavn, 1889, pp. 43–66, 2 Pls.)
=Blanc, Louis.= Étude sur la sécrétion de la soie et la structure du
brin et de la bave dans le _Bombyx mori_. Lyon, 1889, pp. 48, 4 Pls.
—— La tête du _Bombyx mori_ à l’état larvaire. Anatomie et
physiologie. (Extrait du volume des Travaux du Laboratoire d’Études
de la Soie. Années 1889–1890, Lyon, 1891, pp. 180, 95 figs.)
=Gilson, G.= Recherches sur les cellules sécrétantes. La soie et les
appareils séricigènes: I. Lépidoptères. (La Cellule, 1890, vi, pp.
115–182, 3 Pls. I, Lépidoptères (suite); II, Trichoptères. Ibid., x,
pp. 71–93, 1893, 1 Pl.)
=Garman, H.= Silk-spinning dipterous larvæ (Science, xx, 1893, p.
215).
Also the writings of Meckel, Pictet, Duméril, Klapálek,
Wistinghausen, Loew, Hagen, Fritz Müller, Kolbe, McLachlan, de
Selys-Longchamps.
_c._ The cæcal appendages.
These diverticula of the mid-intestine (“stomach”) are appended to the
anterior end, and in the living, transparent larva of Sciara, which has
two large, long, slender cœca (Fig. 341), the partly digested food may
be seen oscillating back and forth from the anterior end of the stomach
into and out of the base of each cæcum. In the Locustidæ (Anabrus, Fig.
299) and Gryllidæ (Fig. 344, _e_) there are two large, short cæca, and
in the locusts (Caloptenus) there are six cæca, while cockroaches have
eight. In the Coleoptera (Carabidæ and Dyticidæ) these large cæca appear
to be replaced by very numerous slender, minute villi or tubules, which
arise from the anterior part of the stomach (Figs. 317, _r_, also 342).
These cæca differ in structure from the stomach, as shown by Graber, as
well as by Plateau and by Minot. The latter states that a single
transverse section of one of the diverticula of the locust demonstrates
at once that its structure is entirely different from that of the
stomach.
[Illustration:
FIG. 341.—Larva of Sciara: _s.gl_, salivary gland; _ur.t_, urinary
tubes; _i_ intestine; _st_, stomach; _cae_ cæcal appendages; _t_,
testis.
]
Its inner surface is thrown up into longitudinal folds, generally
twelve in number. These folds shine through the outer walls, and are
accordingly indicated in the drawings of Dufour, Graber, and others.
The entire cæcum has an external muscular envelope, outside of which
are a few isolated longitudinal muscular bands. The folds within are
formed mainly by the high cylindrical epithelium which lines the
whole interior of the cavity. Tracheæ ramify throughout all the
layers outside the epithelium. There are appearances of glandular
follicles in the bottom of the spaces between the folds. (Minot.)
Burmeister supposed that these cæca were analogous to the pancreas, and
this view has been confirmed by Hoppe Seyler, Krukenberg, Plateau, and
others, who claim that the digestive properties of the fluid secreted in
them agrees with the pancreatic fluid of vertebrates.
[Illustration:
FIG. 342—Cross-section of mid-intestine of _Acilius sulcatus_, showing
the arrangement of the cæca, two tracheæ passing into each
cæcum.—After Plateau.
]
_d._ The excretory system (urinary or Malpighian tubes)
The excretory matters or waste products of the blood tissue of worms are
carried out of the body by segmentally arranged tubes called
_nephridia_. As a rule they arise in the blood sinuses of the body and
open externally through minute openings in the skin. As there is a pair
to each segment (in certain oligochete worms two or three pairs to a
segment), they are often called segmental organs. In the annulate worms
each segment of the body, even the cephalic or oral segment, originally
contains a pair of these excretory organs. These vessels may have
survived in myriopods and perhaps do exist in insects as urinary tubes,
and also occur in many of the Arachnida, and thus are characteristic of
each important class of land arthropods, but are either wanting or are
very rudimentary or much modified in the marine classes, notably the
Crustacea and Merostomata (Limulus), where they are represented by the
shell-glands of Copepoda, green glands of the lobster, and the brick-red
glands of Limulus.
[Illustration:
FIG. 343.—Digestive canal of _Perla maxima_: _l_, upper lip; _mh_,
buccal cavity; _ap_, common end of salivary ducts (_ag_); _o_,
œsophagus; _s_, _s_, salivary glands, arranged segmentally; _b_,
cæca of chyle-stomach; _lg_, their ligaments of attachment; _mp_,
urinary tubes; _r_, rectum; _af_, anal orifice.—After Imhof, from
Sharp.
]
In the earliest tracheate arthropod, Peripatus, these tubes are well
developed and are highly characteristic, each segment behind the head
bearing a pair (Fig. 4, _so_{4}_-_so_{9}_). It has been suggested by
some, but not yet proved, that the urinary tubes of insects are
morphologically the same as the segmental organs of worms and of
Peripatus; but there are no facts directly supporting this view, and, as
Sograff states, it is a pure hypothesis and can only be confirmed or
disproved by very detailed researches on the development of the urinary
tubes of myriopods and of insects. Others regard them as probably
homologous with the tracheæ, since they have a similar origin. As,
however, they arise in the embryo as outgrowths of the proctodæum they
may have arisen in myriopods and insects independently, and not be
vermian heirlooms.
While in worms and in Peripatus a pair of these segmental organs occur
in each segment, in insects this serial arrangement is not apparent;
those with a purely excretory function are not segmentally arranged,
with outlets opening externally, but arise as outgrowths of the
hind-intestine or proctodæum of the embryo, not being segmentally
arranged. The place of their origin is usually the dividing line between
the mid and hind intestine (Fig. 343, _mp_); this applies to
Scolopendrella (Fig. 15, _urt_) as well as to insects.
The urinary tubes are usually long, slender, blind, tubular glands
varying in number from two to over a hundred, which generally arise at
the constriction between the mid and hind intestine, and which lie
loosely in the cavity of the body, often extending towards the head, and
then ending near the rectum (Figs. 301, 310, _vm_). They were first
discovered by the Italian anatomist Malpighi, after whom they were
called the Malpighian tubes. While at first generally regarded as
“biliary” tubes, they are now universally considered to be exclusively
excretory organs, corresponding to the kidneys of the higher animals.
[Illustration:
FIG. 344.—Digestive canal and appendages of the mole-cricket; _a_,
head: _b_, salivary glands and receptacle; _c_, lateral pouch; _d_,
stomatogastric nerves; _e_, anterior lobes of stomach; _f_, peculiar
organ; _g_, neck of stomach; _h_, plicate part of same; _i_, rectum;
_k_, anal gland; _m_, urinary tubes.—After Dufour, from Sharp.
]
Usually arising from the anterior end of the hind-intestine where it
passes into the mid-intestine, in certain forms they shift their
position, in some Hemiptera (Lygæus, Cimex) opening into the rectum,
while in the Psyllidæ they arise from the slender hinder part of the
mid-intestine, being widely separated at their origin. (Fig. 321.)
The length varies in different groups; where they are few in number (two
to four, six to eight), they are very long, but where very numerous they
are often short, forming dense tufts, each tuft connecting with the
intestine by a common duct (ureter), or, as in the mole-cricket, the
numerous tubes empty into a single duct (Fig. 344); in the locusts
(Acrydiidæ), however, they are arranged in 10 groups, each group
consisting of about 15 tubes, making about 150 in all; and are much
convoluted and wound irregularly around the digestive canal, and when
stretched out being about as long as the entire body.
The urinary tubes occur in twos, or in multiples of two, though a
remarkable exception is presented in the dipterous genera Culex and
Psychodes, in which there are five tubes; the young and fully grown
larvæ, as well as the pupa and imago of Culex, having this number (Fig.
433, _mg_.)
In many insects (Pentatoma, Cimex, Velia, Gerris, Haltica, Donacia,
and often in caterpillars), the vessels open into a sort of urinary
bladder connecting with the intestine on one side.
[Illustration:
FIG. 345.—_A_, section of urinary tube of Periplaneta; _B_, part of
tube of Perla; _p_, peritoneal membrane; _c_, cavity or lumen;
_n_, nucleus of a secreting cell.—After Schindler.
]
In the larvæ of some insects the blind ends of the tubes are often
externally bound to the rectum, in the silkworms being attached by
fine threads to the intestine, while in some flies (Tipula and
Ctenophora), two vessels may unite to form a loop. In all larval
Cecidomyiæ, the two tubes are united to form a loop which curves
backward, opening near the vent, the proctodæum being very short.
(Giard.)
[Illustration:
FIG. 346.—Portion of a urinary tube of _Calliphora vomitoria_: _tr_,
trachea; _l_, lumen; _k_, nucleus.—After Gegenbaur.
]
While usually the urinary vessels form simple tubes, in many species
of Lepidoptera and Diptera they are branched, thus resembling those
of spiders and scorpions. Moreover, in many Lepidoptera and Diptera
(Fig. 308), the tubes are not simple, but are lobulated, and in some
Hemiptera (Pentatoma, Notonecta, and Tettigonia) are twisted or
lace-like. In rare cases there are two kinds of urinary tubes; in
_Melolontha vulgaris_, two of them are partly lobulated and yellow,
while the other two are simple and white. Their color in beetles
varies, some being whitish or yellowish; in Geotrupes, Dyticidæ,
Hydrophilidæ, etc., reddish brown; in Gryllotalpa as well as
_Locusta viridissima_, there are two different kinds of vessels,
differing in contents and in color (white or yellow), as well as
histologically. (Schindler.)
The exterior of the tubes is richly provided with tracheæ, which
often form a web around them, and the fine branches often seem to
attach them to the intestine. In Acheta they are enveloped by a very
delicate, loose network of muscular fibres. (Schindler.)
The urinary tubes consist, according to Schindler, of at least three
cellular layers (Fig. 345):—
1. An external, connective, nucleated membrane, the peritoneal
membrane.
2. A very delicate homogeneous basal membrane, the _tunica propria_.
3. A single layer of large polygonal excretory cells.
4. Lining the internal canal a chitinous layer penetrated by
pore-canals, the _intima_ often wanting.
The secretory cells are usually of the same size, but in many cases
are relatively small; sometimes four to six or more form the
periphery of the canal, sometimes three or only two. In some insects
the cells are so very large that a single cell forms the entire
periphery. The nuclei in the Lepidoptera (Papilio, Pontia, Cossus)
are large and irregularly branched.
The excretions of the Malpighian vessels, derived from the blood and
from the fat-body, are more or less fluid and granular, sometimes
pulpy. From the cells they pass into the canal, thence into the
intestine, and thence out of the body. How, says Kolbe, the
secretion passes into the intestine, whether by the contraction of
the fine fibrillæ of the peritoneal membrane, or by the external
pressure of the other organs, or by the pressure of the secretory
matter behind, is not yet known. Grandis observed in living
Hydrophilus that the urinary tubes moved, without the muscles
seeming to show what caused the motion. Moreover, the cells
incessantly changed their form. At a lower temperature such motions
ceased. The tracheæ, ending freely in the cells, did not anastomose.
(Kolbe.)
The different colors of the tubes (white, yellow, red, brown, or
green) is due to the hue of the excretions, and is independent of
the color of the blood and of the urinary substances held in the
secreted matter.
Schindler found that insects of different stages, collected in
winter, differed very much in their urinary secretions, the tubes in
the adults being entirely empty, while in the larvæ they were filled
full, so that he concluded that in the former the process of
excretion during the winter hibernation is very slow, but in the
latter very rapid.
As to the activity of the urinary vessels the following experiments
will throw some light. Tursini fed a Pimelia with fuchsin; its
urinary tubes were consequently colored red. Schindler fed insects
with indigo-carmine, which was excreted by the urinary tubes;
Kowalevsky arrived at the same results, which seems to prove that
these vessels are analogous to the kidneys of vertebrates. Moreover,
Schindler injected through the side of the first abdominal segment
into the cavity of the body of a Gryllotalpa a concentrated solution
of sodium salt of indigotin-disulphonic acid. After one or two hours
the external portion of the epithelium of the urinary vessels was
stained deep blue, while the inner portion remained of the normal
transparency; the nuclei being for the most part deeply stained.
Between one and two days after, the staining matter had not yet
wholly passed through the central canal, the surface recently
stained still appearing light blue.
The solid contents of the urinary tubes consist partly of crystals,
which occur singly in the epithelial cells, or form scattered masses
when situated in the central canal. Besides tabular rhombic crystals,
there occur concretions which contain uric acid, and probably consist of
urate of soda, also octahedral crystals of chloride of soda, and
quadro-pyramidal crystals of oxalate of lime. Also acicular prisms
occur; besides chloride of soda, phosphates, carbonate of lime, oxalate
of lime in quantity, leucine, coloring matters, etc.; while the fluid
secretion also contains urea (?), uric acid, and abundant urates; uric
acid crystals were precipitated by the addition of acetic acid, and by
adding hydrochloric acid crystals belonging to the dimetric system were
formed. The often numerous spheroidal small granules are biurate of soda
and biurate of ammonia. Pale, concentrically banded concretions are
leucine pellets.
According to Kölliker the contents of the urinary vessels[55] in
general are: (1) round granules of urate of soda and urate of
ammonia; (2) oxalate of lime; and (3) pale transparent concretions
of leucine. Crystals of taurin are also said to occur. (Claus’
Zoölogy, p. 531.)
Although uric acid is characteristic of the urinary tubes, yet
sometimes it is wanting in them, while uric acid substances in
quantity occur in the fat-body or in the mid-intestine.
In the living insect the urinary tubes remove urates from the blood;
“the salts are condensed and crystallized in the epithelial cells,
by whose dehiscence they pass into the central canals of the tubules
and thence into the intestine.” (Miall and Denny.)
The process of excretion is carried on not only by the urinary
tubes, but also, as Cuénot has recently shown (1896) in Orthoptera,
by the pericardial cells and certain cells of the fat-bodies. In the
last-named cells urates are stored throughout life; the pericardial
cells apparently secrete but do not store waste products, which are
finally eliminated by the urinary tubes, the latter constantly
eliminating waste.
=Primitive number of tubes.=—Wheeler considers the primitive number
of urinary tubules to be six, other authors regarding two pairs as
the primary or typical number; and while Wheeler agrees that the
more ancestral tracheate arthropods had but a single pair,
Cholodkowsky supposes the primitive number in insects themselves to
be a single pair. This view is strengthened by the fact that
Scolopendrella has but a single pair (Fig. 15).
While Peripatus has no urinary tubes, in Myriopods a single pair
arises, as in insects, from the hind-intestine.
[Illustration:
FIG. 347.—Section of proctodæum of embryo locust, showing origin of
urinary tubes (_ur.t_); _ep_, epithelial or glandular layer; _m_,
cells of outer or muscular layer; _a_, section of a tube.
]
When in insects the number of these tubes is few, they are, with
rare exceptions, arranged in pairs, so that Gegenbaur and others
have considered this paired arrangement as the primitive one. When
the tubules are very numerous in the adult, as in Orthoptera, the
embryos and larvæ have a much smaller number, Wheeler stating that
“in no insect embryo have more than three pairs of these vessels
been found.” We have observed 10 primary tubes in the embryo of
Melanopus (Fig. 347), from each of which afterwards arise 15
secondary tubules. In the Termites, only, do the young forms have
more urinary tubes than the adults.
In Campodea there are about 16 urinary tubes and in Machilis either
12 (Grassi) or 20 (Oudemans); but in other Thysanura the number is
much less, Lepisma having either four, six, or eight, according to
different authors, and both Nicoletia and Lepismina having six,
opening separately into the hind-intestine. On the other hand, these
organs have not yet been detected in Japyx. Whether they exist at
all in the Collembola, which are degenerate forms, is doubtful. The
weight of opinion denies their existence, though they may yet be
found existing in a vestigial condition. They are said by Tullberg
and by Sommer to exist in Podura, but are of peculiar shape.
Coming now to the winged insects, in what on the whole is perhaps
the lowest or most generalized order, the Dermaptera, the number is
over 30, and their insertions regularly encircle the intestine.
(Schindler.) In the most ancient and generalized family of
Orthoptera, the Blattidæ, Schindler detected from 60 to 70 tubes,
but in a nymph of Periplaneta not quite 10 mm. in length he found
from 16 to 18, and in nymphs 4 to 5 mm. long there were only eight
vessels; while Wheeler has found in the embryo of _Phyllodromia
germanica_ but four tubes. In the adult Acrydiidæ there are as many
as 150, in the Locustidæ between 40 and 50, and in the Gryllidæ
about 100.
The Ephemeridæ with about 40, the Odonata with 50 to 60 tubules, the
Perlidæ with from 50 to 60, are polynephrious; while the Termitidæ
and Psocidæ are oligonephrious, the former having from six to eight
and the Psocidæ only four tubes. So also all the other orders not
mentioned, except the Hymenoptera, have few of these tubes. The
Hemiptera, with none in Aphidæ, a single pair in the Coccidæ, and
two in all the rest of the order, have the fewest number.
In the Neuroptera there are from six to eight, while in a larva,
possibly that of Chauliodes, Wheeler finds the exceptional number of
seven.
The closely allied order Mecoptera (Panorpidæ), and also the
Trichoptera, agree with the Neuroptera (Sialis) in having six.
According to Cholodkowsky all Lepidoptera have six of these vessels,
except Galleria, which has but four. He finds that in _Tinea
biselliella_ (also _T. pellionella_ and _Blabophanes rusticella_)
the larva has six vessels, which, however, undergo histolysis during
pupation, a single pair arising in their stead. On this account he
regards the primitive number of urinary tubes as two, or a single
pair, this return from six vessels in the larva to two in the imago
being considered a case of atavism.
In the Coleoptera, the number of urinary tubes is from four to six;
in what few embryo beetles have been examined (Doryphora,
Melolontha), there are six vessels, but in the embryo of _Dyticus
fasciventris_, Wheeler has detected only four, this number being
retained in the adult. He thinks that in beetles in general, a pair
of vessels must be “suppressed during post-embryonic development,
presumably in early larval life.”
In Diptera and Siphonaptera, the number four is very constant, there
being, however, a fifth one in Culex and Psychoda (Fig. 400.)
The number of these vessels is very inconstant in the Hymenoptera,
varying from six (Tomognathus, an ant, worker) to 12 (Myrmica), and
in Apis reaching the number of 150.
In the embryo of the honey-bee and wall-bee (Chalicodoma), there are
only four; we still lack any knowledge of the number in embryo
saw-flies.
The following is a tabular view of insects with few urinary tubes
(Oligonephria) and many (Polynephria). It will be seen that the number
has little relation to the classification or phylogeny, insects so
distantly related as the Orthoptera and Hymenoptera being
polynephrious:—
_Oligonephria_
Collembola, 2 (Podura), Tullberg and also Sommer.
Thysanura, 4 (Lepisma); in Campodea, 16; in Machilis, 12 or 20; wanting
in Japyx.
Psocidæ, 4.
Termitidæ, 6 (many in the young, Rathke).
Mallophaga, 4.
Physapoda, 4.
Hemiptera, 2 (Coccidæ, none in Aphidæ).
Neuroptera, 6–8. (In Sialidæ and Rhaphididæ 6; in Myrmeleonidæ and
Hemerobiidæ, 8).
Trichoptera, 6.
Mecoptera, 6.
Lepidoptera, 2–4–6 (2 in Tinea, Tineola, and Blabophanes; in Pterophorus
and Yponomeuta, 4).
_Coleoptera_, 4–6; never more.
4
Carabidæ,
Dyticidæ,
Staphylinidæ,
Gyrinidæ,
Palpicornes,
Lamellicornes,
Cantharidæ,
Buprestidæ
(in larva, 6; in beetle, 4).
6
Byrrhidæ,
Nitidulidæ,
Dermestidæ,
Cleridæ,
Meloidæ,
Pyrochroidæ,
Bruchidæ,
Bostricidæ,
Cerambycidæ
Chrysomelidæ,
Coccinellidæ.
Diptera, branching into 4 (Gegenbaur); in Culicidæ, and Psychoda, 5.
Siphonaptera, 4.
_Polynephria_
Orthoptera, 100–150. (In embryo Blattids, 4; in embryo locust, 10; in
nymph of Gryllotalpa, 4.)
Dermaptera, “over 30” (Schindler).
Perlidae, 50–60.
Plectoptera (Ephemeridæ), 40.
Odonata, 50–60.
Hymenoptera, 20–150. (In embryo bees only 4; Cynipidæ, Ichnenumonidæ,
and Formicidæ have the smallest number, 6–12.)
Here should be mentioned the singular fact discovered by Koulaguine
that in the larva of Microgaster, the urinary tubes have no
connection with the intestine, but open dorsally on the outside of
the body on each side of the anus. Ratzeburg had stated that the
last segment of the body was in the form of a vesicle. Koulaguine
now shows that this vesicle is in reality the end of the intestine
opening upwards; as the result of this dorsal opening of the
intestine the Malpighian vessels open on the sides of the oval vent,
and have no connection with the intestinal canal. Whether this is of
morphological import, or is only a secondary adaptation, Koulaguine
does not state, his paper being a preliminary abstract.
Wheeler thus sums up our present knowledge regarding the number and
homologies of the Malpighian or urinary tubes:
1. It is very probable that the so-called Malpighian vessels of
Crustacea and Arachnida are not the homologues of the _vasa
Malpighi_ of the Eutracheata (insects and myriopods).
2. The Malpighian vessels of the Eutracheata arise as paired
diverticula of the hind-gut and are, therefore, ectodermal.
3. In no insect embryo are more than six vessels known to occur;
although frequently only four are developed.
4. The number six occurs either during embryonic or post-embryonic
life in members of the following groups: Apterygota, Orthoptera,
Corrodentia; Neuroptera, Panorpata, Trichoptera, Coleoptera,
Lepidoptera, and Hymenoptera.
5. The number four seems to be typical for the Corrodentia,
Thysanoptera, Aphaniptera, Rhynchota, Diptera, and Hymenoptera.
6. The embryonic number in Dermaptera, Ephemeridea, Plecoptera, and
Odonata has not been ascertained, but will probably be found to be
either four or six.
7. There is evidence that in at least one case (Melolontha), the
tetranephric is ontogenetically derived from the hexanephric
condition by the suppression of one pair of tubules.
8. It is probable that the insects which never develop more than
four Malpighian vessels have lost a pair during their phylogeny.
9. The post-embryonic increase in the number of Malpighian vessels
in some orders (Orthoptera, Odonata, Hymenoptera) is secondary and
has apparently arisen to supply a demand for greater excreting
surface.[56]
LITERATURE ON THE EXCRETORY (URINARY) ORGANS
=Malpighi, M.= Dissertatio epistolica de Bombyce, Societati regiæ
Londini ad scientiam naturalem promovendam institutæ dicata.
(Londini, 1669, 12 Pls.)
=Herold, M. J. D.= Entwicklungeschichte der Schmetterlinge. 1815.
=Rengger, J. R.= Physiologische Untersuchungen über den tierischen
Haushalt der Insekten. Tübingen, 1817, pp. 82.
=Wurzer.= Chemische Untersuchungen des Stoffes in den Gallgefässen von
_Bombyx mori_. (Meckel’s Archiv f. Physiol., iv, 1818, pp. 213–215.)
=Gaede, H. M.= Physiologische Bemerkungen über die sogenannten
Gallgefässe der Insekten. (Nova Acta Acad. Caes. Leopold.-Carolin.,
1821, x, Pars II, pp. 186–196.)
=Meckel, J. F.= Ueber die Gallen- und Harnorgane der Insekten.
(Meckel’s Archiv, i, 1826, pp. 21–36.)
=Audouin, J. V.= Calculs trouvés dans les canaux biliaires d’un cerf
volant. (Ann. sc. nat., 2 Sér., 1836, v, pp. 129–137.)
=Frey und Leuckart.= Anatomie und Physiologie der Wirbellosen. 1843.
=Dufour, L.= Mémoire sur les vaisseaux biliaires ou le foie des
Insectes. (Ann. sc. nat., 1848, Sér. 2, xix, pp. 145–182, 4 Pls.)
=Karsten, H.= Harnorgane von _Brachinus complanatus_. (Müller’s Archiv
f. Anat. und Physiol., 1848, pp. 367–374.)
=Fabre, J. L.= Étude sur l’instinct et les metamorphoses des
Sphégiens. (Ann. d. sc. nat., 4 Sér., 1856, vi, pp. 137–189.)
—— Étude sur le rôle du tissu adipeux dans la sécrétion urinaire chez
les Insectes. (Ibid., 4 Sér., xix, pp. 351–382.)
=Schlossberger, J. E.= Untersuchungen über das chemische Verhalten der
Krystalle in den Malpighischen Gefässen der Raupen. (Archiv f. Anat.
und Physiol., 1857, pp. 61–62.)
=Leydig, F.= Lehrbuch der Histiologie. 1857.
=Sirodot, S.= Recherches sur les sécrétions chez les Insectes. (Ann.
sc. nat., 4 Sér., Zool., 1858, x, pp. 141–189, 251–334, 12 Pls.)
=Kölliker, A.= Zur feineren Anatomie der Insekten (Ueber die
Harnorgane, u.s.w.) (Verhandl. d. Physikal.-medizin. Gesellsch. in
Würzburg, viii, 1858, pp. 225–235.)
=Schindler, E.= Beitrage zur Kenntnis der Malpighischen Gefässe der
Insekten. 3 Taf. (Zeitschr. f. wiss. Zool., xxx, 1878, pp. 587–660.)
=Chatin, G.= Note sur la structure du noyau dans les cellules
marginales des tubes de Malpighi chez les Insectes et les
Myriapodes. (Ann. d. sc. nat., 6 Sér., xiv., 1882, pp. 7, 1 Pl.)
=Witlaczil, E.= Zur Anatomie der Aphiden. (Arbeiten a. d. Zool.
Instit. d. Univers. Wien., iv, 1882, pp. 397–441, 3 Taf.)
=Cholodkowsky, N.= Sur les vaisseaux de Malpighi chez les
Lépidoptères. (Compt. rend. Acad. d. Sc., Paris, xcix, 1884, pp.
631–633.)
—— Sur la morphologie de l’appareil urinaire des Lépidoptères.
(Archives de Biologie, 1887, vi, pp. 497–514, 1 Pl.)
=Loman, J. C. C.= Ueber die morphologische Bedeutung der sogenannten
Malpighischen Gefässe der echten Spinnen. (Tijdschr. Nederl. Dierk.
Ver. (2) Deel 1, 1887, pp. 109–113, 4 Fig.)
=Marchal, P.= Contribution à l’étude de la désassimilation de l’azote.
L’acide urique et la fonction rénale chez les Invertébrés. (Mém.
Soc. Zool. de France, 1889, iii, pp. 42–57.)
=Kowalevsky, A. O.= Ein Beitrag zur Kenntnis der Exkretionsorgane.
(Biol. Centralbl., ix, 1889–90, pp. 33–47, 65–76, 127–128.)
—— Sur les organes excréteurs chez les arthropodes terrestres.
(Congrès international de Zool., 2^{me} Session à Moscou, 1892, Pt.
I, pp. 186–235, 4 Pls.)
=Griffiths, A. B.= On the Malpighian tubules of _Libellula depressa_.
(Proc. Roy. Soc., Edinburgh, 1889, xv, pp. 401–403, Figs.)
=Grandis, V.= Sulle modificazioni degli epitelii ghiandolari durante
la secrezione. (Atti Accad. Torino, 1890, xxv, pp. 765–789, 1 Pl.;
Archiv Ital. Biol., 1890, xiv, pp. 160–182, 1 Pl.)
=Koulaguine, N.= Notice pour servire à l’histoire du développement des
hyménoptères parasites. (Congrès internat. de Zool., 2^{me} Session
à Moscou, 1892, Pt. I, pp. 253–277.)
=Sograff, Nicolas.= Note sur l’origine et les parentés des
Arthropodes, principalement des Arthropodes trachéates. (Congrès
internat. de Zool., 2^{me} Session à Moscou, 1892, Pt. I, pp.
278–302.)
=Giard, Alfred.= (Note on the urinary tubes of larval Cecidomyia.
Annals Ent. Soc., France, lxii, 1893, pp. lxxx-lxxxiv, 1 Fig.)
=Wheeler, William M.= The primitive number of Malpighian vessels in
insects. (Psyche, vi, May-December, 1893, Parts 1–6, pp. 457–460,
485–486, 497–498, 509–510, 539–541, 545–547, 561–564.)
=Metalnikoff, C. K.= Organes excréteurs des insectes. (Bull. Acad.
imp. Sci. St. Pétersbourg, 1896, iv, pp. 57–72, in Russian, 1 Pl.)
See also the works of Straus-Dürckheim, Will (Müller’s Archiv. 1848,
p. 502), Brugnatelli, Leidy, Dufour, Ramdohr, Basch, Davy, Grassi,
Minot, Berlese, Adlerz, Marchal (Bull. Ent. Soc. France, 1896, p.
257); Bordas (Appareil glandulaire des Hyménoptères, 1894), also C.
R. Acad. Sc. Paris, 1897.
_e._ Poison-glands
Poison-glands are mainly confined to the stinging Hymenoptera, _i.e._
certain ants, and the wasps and bees, but also occur in the mosquito,
while many, if not most bugs, seem to instil a drop of poison into the
punctured wounds they make.
In the honey and other bees the poison apparatus consists of two
poison-glands whose secretion passes by a single more or less convoluted
efferential duct into the large poison-sac, and thence by the excretory
duct, which is enlarged at the base of the sting (Figs. 194, 195), out
through the sting by the same passage as the eggs. According to Carlet,
the poison apparatus of bees consists of two kinds of glandular organs,
of which one kind secretes a feebly alkaline fluid, the other an acid
product. The poison is only effective when both fluids are mixed. The
resultant venom is always acid. The action of this venom upon some
animals, as rabbits, frogs, and certain beetles, is slight; but the
domestic fly and the flesh-fly are immediately killed by it. The
inoculation of a fly with the secretion of one of the glands does not
produce death until after a considerable time, but death follows very
quickly if the same fly is subjected to a second inoculation, this time
with the secretion of the other gland. The alkaline glands are in bees
and all poisonous Hymenoptera strongly developed, but become vestigial
in those forms which sting their prey to serve as food for their larvæ.
The poison which the solitary sand and wood wasps and Pompilidæ inject
into their victims only paralyzes them.
[Illustration:
FIG. 348.—The poison apparatus of Ichneumon: _T_, sting; _GA_ acid
gland; _TG_, _R′_, its tubes opening into the common poison-sac or
reservoir; _ce_, its efferent canal; _Ga_, the tubular alkaline
gland; _R_, the glandular end; _a_, the reservoir; _ce_, its duct;
_Gac_, the accessory gland—After Bordas.
]
[Illustration:
FIG. 349.—Cephalic gland of Belostoma.
]
Bordas has found both the alkaline gland (gland of Dufour) and the
acid gland to occur in a hundred species of Hymenoptera, including
not only Aculeata, but also Ichneumonidæ (Fig. 348), Tenthredinidæ,
and they may be safely said to be of general occurrence. The acid
gland consists of three parts, the glandular portion, the reservoir
for the poison, and the secretory canal. The alkaline gland is an
irregular tube, with a striated surface and without a reservoir. In
most Hymenoptera there is still a third gland, which is unpaired,
granular, rectangular or lanceolate, with a short filamentous duct
which opens beside the orifice of the alkaline glands.
The poison in ants, wasps, and bees consists of two substances, _i.e._
formic acid and a whitish, fatty, bitter residue in the secretion of the
glands; the corroding active formic acid is the essential part of the
poison. (Will.)
In Melipona the sting and poison-glands are aborted; in certain ants
(Formica, Lasius, etc.) the sting is wanting, but the poison-sac is
extraordinarily large.
Bordas finds in various species of Ichneumon three kinds of glands
opening into the base of the sting. The first two correspond to the
acid (Fig. 348, _G.A_) and alkaline (_G.A_) glands of bees and wasps
(Vespidæ, etc.), and the third (_G.ac_) is situated between the two
lateral muscular bundles which attach the base of the sting to the
last abdominal segment. The poison-reservoir (Fig. 348, _V_) is
recognized by its yellow color and diaphanous and striated
appearance. It is situated on the left of the hind-intestine, a
little in front of the rectum. The tubular gland (_Ga_) or alkaline
gland of aculeate Hymenoptera is remarkably large; it is situated on
the left side of the body. The accessory gland (_G.A_) is elongated,
triangular, flat, its duct opening at the base of the alkaline
gland; it is formed of small spherical cells. Bordas has met with
well-developed poison-glands in forty species belonging to the
Terebrantia, including that of Tenthredo, Emphytus, as well as
various genera of Ichneumonidæ, but in all these species the
accessory gland was wanting.
[Illustration:
FIG. 350.—View from above of the cephalic gland of Belostoma, ×
20.—This and Fig. 349 after Locy.
]
Under the name of cephalic glands (Fig. 349), Locy describes a pair of
glands in the head of Nepidæ. The epithelial or secreting cells are
8–sided (Fig. 350). “When these insects are irritated,” he says, “a
secretion is freely thrown out around the base of the beak, which
produces death very quickly when introduced on a needle point into the
body of an insect.” He infers that the cephalic glands may be the source
of this poisonous secretion. The poisonous salivary fluid of the larva
of Dyticus is referred to on p. 324.
That the mosquito injects poison into the wound it makes has been proved
by Macloskie, who discovering fine droplets of a yellow oily-looking
fluid escaping from the end of the hypopharynx, afterwards detected the
poison-glands. It appears that the two salivary glands are subdivided,
each into three lobes, the middle of which (Fig. 351, _pg_) differs from
the others in having evenly granulated contents and staining more deeply
than the others. Having examined the preparations, we agree with the
discoverer that these lobes secrete the poison. The poison is diluted by
the secretion of the salivary lobes, and the two efferent ducts, one
from each set of glands, “carry forward and commingle the
venomo-salivary products in the main duct; and the stream is then
carried by the main duct to the reservoir at the base of the
hypopharynx.”
[Illustration:
FIG. 351.—_A_, median section of head, showing (_du_) the
venomo-salivary duct, with its insertion in (_hy_) the hypopharynx;
_cb_, brain; below is the pharyngeal pump, leading from (_œ_) the
œsophagus; _lre_, base of labrum-epipharynx; _m_, muscle; _n_,
commissure (other parts removed). _B_, the venomo-salivary duct,
showing its bifurcation, and the three glands on one of its
branches; _pg_, poison gland; _sg_, the upper of the two salivary
glands. _C_, the bifurcation of the duct, with its nucleated
hypodermis.—After Macloskie.
]
_f._ Adhesive or cement-glands
Dewitz has discovered in ants and bees, in close connection with the
poison-glands, and like them discharging their secretion through the
sting, cement-glands. They arise by budding at the base of the
poison-glands.
The two glands in these Hymenoptera correspond to the tubular glands of
the Orthoptera, which open at the base of the inner sheath of the
ovipositor (Fig. 299, _sb_), so that the secretion flows out through it
as the poison of bees, etc., out of the sting. The use of the secretion
of these glands is either to glue the eggs together, or to afford
material for the egg-case of cockroaches and Mantidæ and the gummy
egg-case of the locusts, etc. The contents of the cement-glands serves
for the fixture of the eggs after deposition. In the stinging
Hymenoptera one of the cement-glands is an accessory gland; the other
becomes the poison-sac. The cement-glands are in the Hemiptera only
short blind sacs, in the Lepidoptera and Diptera long convoluted tubes,
tubular and branched in the Coleoptera, or richly branched in the
Ichneumonidæ and Tenthredinidæ. In the cockroach there are two
cement-glands, but the right one is probably of no functional
importance. The left one is filled with a milky substance, containing
many crystals and a coagulable fluid, out of which the egg-capsule
(oötheca) is formed. (Miall and Denny.) In the locusts the sebific or
cement-gland (Fig. 298, _sb_) secretes a copious supply of a sticky
fluid, which is poured out as the eggs pass out of the oviduct and
agglutinates the eggs into a mass, forming a thin coating around each
egg, which from the mutual pressure of the eggs causes the tough coating
to be pitted hexagonally. In other insects also (Trichoptera,
Chrysopidæ, Lepidoptera, etc.) there are similar secretions for the
protection or fastening of the eggs when laid.[57] The Trichoptera lay
their eggs either in or on the surface of the water in bunches or in
strings or in annular gelatinous masses on stones or on plants. This
jelly-like substance is secreted by two highly developed paired anal
glands. (Weltner, in Kolbe, p. 621.) Also in certain dragon-flies
(Libellula, Diplax, and Epitheca) the eggs are laid in jelly-like
masses.
With a similar secretion, spun from the end of the abdomen, the Psocidæ
cover their little bunches of eggs laid on the under side of leaves; and
the silk thread forming the egg-sac of the great water-beetle
(Hydrophilus) is secreted from such anal glands.
_g._ The wax-glands
Besides the honey-bee, which secretes wax in little scales on the under
side of the abdomen, the bodies of many other insects, such as the plant
and bark lice, as well as the Psyllidæ, Cicadidæ (especially Flata and
Lystra), are covered with a waxy powder, or as in Chermes, Schizoneura,
Flata, etc., with wool-like filaments of wax.
[Illustration:
FIG. 352.—Under side of worker honey-bee, carrying wax scales, ×
3.—After Cheshire.
]
[Illustration:
FIG. 353.—Nymph of Lachnus, showing position of wax-glands.—Gissler
_del._
]
The wax is secreted by minute unicellular dermal glands, which in the
lower insects (Hemiptera) are distributed nearly all over the body, but
in the bees are restricted either to the under (Apis, Fig. 352) or upper
side (Trigona) of the end of the abdomen.
The wax-glands of Pemphigus, Chermes, etc., lie under the little warts,
seen in _Lachnus strobi_, the white-pine aphis, to be distributed in
transverse lines across the back and sides of the abdominal segments
(Fig. 353). These warts are surrounded by a chitinous ring, and divided
into delicately marked areas. Through the delicate numerous pits in the
chitinous membrane of these areas the little waxen threads project,
since under each area ends a duct leading from a large glandular cell,
which is a specially modified hypodermis cell (Claus). The wax threads
are hollow, and all those arising from a single glued cell form a
bundle, whose threads separate from each other and form a white woolly
down or bloom covering the body. Witlaczil also shows that gall-forming
Aphids secrete a wax-like substance, which, during the movements of the
insects in the gall, is rubbed off, becoming a watery layer mixed with
the fluid excrement, which forms a spherical impervious layer lining the
gall, and thus rendering possible the mode of life of the gall-lice.
In the Psyllidæ Witlaczil has discovered wax-glands which also secrete
slender waxen threads. They are situated in groups of two or three at
the end of the abdomen near the anus, and arise from hypodermis cells.
The wax threads surround the liquid excrement as it passes out of the
vent, covering it with a continuous layer of wax. The excrement
accordingly is discharged very slowly and gradually, in sausage-shaped
masses slightly strung together and rolled into close spirals. The body
becomes unavoidably smeared with the sticky excrement, since it is not
entirely covered by the waxy layer. Moreover, in the larvæ of many
Psyllidæ waxen threads are formed on the upper side of the abdomen; they
are for the most part tightly curled or frizzly, like wool, and form,
though partly torn, a waxen coat, chiefly on the side and back of the
thorax and abdomen. The insects appear therefore as if covered with
dust. The mature animals of many species are also covered with a waxen
down. The wax threads rapidly dissolve and disappear in alcohol. From a
wax-like substance more or less easily dissolved in alcohol arise
peculiar hair-like structures which, in the larvæ of Psyllidæ, are
situated on the side and end of the body and also on the rudiments of
the wings. They are readily distinguished from ordinary hairs, as they
arise from glandular cells, and are of very different lengths, more or
less like bristles, but hollow, and very brittle. They are leaf-like in
the first nymphal stages of _Trioza rhamni_, but in following stages
become narrow and form a row around the entire periphery of the body.
The waxen dorsal shield which protects the body of bark-lice (Coccidæ)
is a similar product.
[Illustration:
FIG. 354.—Young nymph and developing scale of _Aspidiotus
perniciosus_: _a_, ventral view of nymph, showing sucking beak with
setæ separated, with enlarged tarsal claw at right; _b_, dorsal view
of same, somewhat contracted, with the first waxy filaments
appearing; _c_, dorsal and lateral views of same, still more
contracted, illustrating further development of wax secretion; _d_,
later stage of same, dorsal and lateral views, showing matting of
wax secretions and first form of young scale; all greatly
enlarged.—After Howard and Marlatt, Bull. 3, N. S., Div. Ent., U. S.
Dept. of Agr.
]
Witlaczil has described the way it is formed in Aspidiotus and
Leucaspis. The freshly hatched nymph shows no signs of a waxy
secretion. But eventually waxen threads arise first on the hinder
and anterior end of the body, and then over the whole surface. These
threads interlace into a sort of felting and thus form the shield,
which is usually much larger than the body and lies closely upon it.
The shield is formed after the first moult. It is noteworthy that
these threads are matted together to form as thick a tissue as that
of the shield itself. The shield is whitish or gray and rather thin.
On the thinnest part of the edge the single threads may be drawn
out. The growth of the shield advances with the increase in size of
the nymph around the entire edge, but is greatest behind. The first
two larval skins are retained on the back under the shield. Also a
very thin waxen pellicle remains on the resting place of the insect
when it is raised. The wax-glands open in the pitted fields, and
appear as clear brownish cells which are distinguished from the
ordinary hypodermis cells by their greater size. (Witlaczil. Compare
also Fig. 354.)
[Illustration:
FIG. 355.—Wax disks of social bees: _a_, _Apis mellifica_, worker;
_b_, do., queen; _c_, Melipona, worker; _d_, Bombus, worker.—From
Insect Life, U. S. Dept. Agr.
]
The wax-glands in the honey-bee are scale-shaped organs situated on the
under side of the four last abdominal segments (Fig. 355). These secrete
the wax, which appears as whitish scales, and secretion is only possible
when the bees have sufficient honey and pollen. The wax is secreted by
the hypodermal cells rather than by glands within the abdominal cavity;
the wax traverses the cuticular layer, and accumulates on its outer
surface (Carlet). According to Fritz Müller, in the stingless bees
(Trigona) which he observed, the wax-glands are situated on the back of
the abdomen, but Ihering states that in many species of Trigona and
Melipona there are also slightly developed wax-organs on the ventral
side.
It has been found that certain caterpillars secrete wax. Thus the
cells of the Tortrix of the fir (_Retinia resinella_) formed of
resin are lined with wax, as on dissolving away the resin with
alcohol, Dr. Knaggs found a slight film of wax; also a secretion of
wax has been detected in the larva of a butterfly (_Parnassius
apollo_). The bodies of certain saw-fly larvæ are covered with a
white powdery secretion, while the remarkable larva of a Selandria
is clothed with snow-white, long, flocculent, waxy masses, nearly
concealing the body (Fig. 356).
_h._ “Honey-dew” or wax-glands of Aphids
The so-called “honey-dew” of Aphids which oozes from two wart-like
tubercles or tubes situated near the end of the body, is secreted by
hypodermal unicellular glands which open into a modification of a
pore-canal, the tube itself being an outgrowth of the cuticula.
Witlaczil states that both in the “honey” tubes and in the body
beneath, the sugary matter exists in cells of the connective tissue
in the form of granules. “These large ‘sugar-cells’ in contact with
the air undergo destruction, while the sugar crystallizes into
needles, and thus each cell is transformed into a radiated
crystalline mass.”
“A muscle extends from a horseshoe-shaped place (a valve?) in the
middle of the flat terminal plate of the honey tube, through this
and down through the abdomen to the ventral surface. By this muscle
the honey tube is at times erected, and we then find, as also when
we lightly press the body of the insect, lumps of crystallized sugar
which have been expressed through the tips of the honey tubes.”
(Zool. Anzeiger, 1882, p. 241.)
[Illustration:
FIG. 356.—Wax-secreting larva of a saw-fly.
]
[Illustration:
FIG. 357.—_Lachnus strobi_, and its two “honey” warts.—Gissler
_del._
]
Busgen, after careful research, denies that this is a sugar, but
claims as the result of chemical analysis, that it is more like wax.
He observed that on reaching the air the drops issuing from the
“nectary” or “honey” tube stiffened almost instantly into a wax-like
mass, which was easily crushed between the teeth, and had no taste
at all. No sugar-like substance or urea could be detected. He
therefore concludes that the secretion in question should be
regarded as a wax-like mass, which agrees well with Witlaczil’s
anatomical observations, and confirms the statements of previous
observers. Thus, as early as 1815, Kyber stated that the Aphides
expelled an excrementitious substance through the “sap tubes.”
Burmeister states that the tubes give out a fluid which “dries
gumlike, but, so far as I have observed, has no peculiar taste.”
Réaumur, and also Kaltenbach, state that the “honey” does not issue
from the tubes, but from the anus. Lastly, Forel emphatically states
that “the two dorsal tubes of Aphides do not secrete a sweet fluid,
but a gluey wax, which is not sought by the ants. Moreover the
shield-lice and many leaf-lice have no such tubes, but yet are often
sought by ants. The drops of sugar which the ants lick up are rather
the excrement of the insects in question.” Hence the opinion first
stated by Linné, that a sweet fluid is secreted by Aphides, must be
abandoned.
On the other hand, Busgen, after careful observations, finds that
the use of the sticky, waxen secretion is in reality a protective
one, as he observed that when a larval Chrysopa rudely attacks the
Aphides, they smear its face with the sticky wax, causing at least a
momentary interruption in its attacks. He also observed that Aphides
when invaded by coccinellid larvæ set their tubes in motion and
besmear their heads and front part of the body. He thus seems to
establish the fact that these tubes secrete a protective, sticky
fluid.
_i._ Dermal glands in general
We have seen that certain of the hypodermal cells may be modified or
specialized to form secretory unicellular glands. Such are those
(trichogens) which secrete chitinous setæ, hairs, and spines, certain
setæ in some insects being hollow and containing a poison (p. 187);
others secrete wax, certain ones in Aphids “honey-dew”; in some cases
dermal glands may excrete protective, sticky, or otherwise offensive
matters, or may be depuratory, or facilitate the process of moulting.
There are other minute, unicellular, or compound dermal glands whose
function is unknown.
Dermal glands may be segmentally or serially arranged. Thus Verson has
detected a series of one or two pairs of unicellular glands near the
stigmata in each thoracic, and the first eight abdominal segments of the
silkworm (_B. mori_). In the earliest stages of growth of the
caterpillar they give out oxalate of lime, and in later stages uric
acid. They thus appear to act interchangeably with the urinary tubes, as
excretory organs. They do not, however, carry their products directly
outwards, but leave them between the hypodermis and cuticula, in order
to facilitate the sloughing off of the latter in the process of
moulting.
LITERATURE ON THE SECRETORY GLANDS
_a._ General
=Sirodot, S.= Recherches sur les sécrétions chez les Insectes. (Ann.
sc. nat., 4 Sér., Zool., 1858, x, pp. 141–189, 251–328, 12 Pls.)
=Gazagnaire, G.= Des glandes chez les Insectes. (Compt. rend. Acad.
Sc., Paris, 1886, cii, pp. 1501–1503; Annal. Soc. Ent. France, 1886,
Bull., pp. 104–106.)
=Leydig, F.= Beitrage zur Anatomie und Histiologie der Insekten. 1887.
=Hanow, Karl.= Ueber Kerfabsonderungen und ihre Benutzung im eigenen
Haushalte. (Programm des Realprogymnasiums zu Delitzsch für das
Schuljahr 1889, xc; Delitzsch, 1890, pp. 3–22.)
=Verson, E.= Di una serie di nuovi organi escretori scoperti nel
filugello. (Publ. R. Stazione Bacologica di Padova, v, 1890, pp. 30.
4 Pls.)
—— Altre cellule glandulari di origine postlarvale. (Ibid., vii, 1892,
pp. 16, 1 Pl.)
—— =ed E. Bisson=. Cellule glandulari ipostigmatiche nel _Bombyx
mori_. (Ibid., vi, 1891.)
=Borgert, H.= Die Hautdrüsen der Tracheaten. Jena, 1891, pp. 80.
=Batelli, Andrea.= Di una particolarità nell’ integumento dell’
_Aphrophora spumaria_. (Monitore Zool. Ital., 1891, Anno ii., pp.
30–32, dermal gland in last segment.)
=Koschewnikow, G. A.= On a new compound dermal gland found in the
sting of the bee. (Journal of the Zoological Section of the Society
of the Friends of Natural Science. Moscow, ii, Nos. 1, 2, 1892, p.
36. Preliminary notice. In Russian.)
=Willem, V., et H. Salbe.= Le tube ventral et les glandes céphaliques
des Sminthurus. (Ann. Soc. Ent. Belg., 1897, xli, pp. 130–132.)
=Henseval, Maurice.= Les glandes à essence der _Cossus ligniperda_.
(La Cellule, 1897, xii, pp. 19–26, 27, 29.)
—— Recherches sur l’essence der _Cossus ligniperda_. (La Cellule,
1897, xii, pp. 169–181, 183.)
_b._ Poison-glands
=Macloskie, George.= The poison-apparatus of the mosquito. (Amer.
Nat., xxii, 1888, pp. 884–888. 1 Fig. Also in Science, 1887, p.
106.)
=Beyer, Otto W.= Der Giftapparat von _Formica rufa_, ein reduziertes
Organ. (Jena. Zeitschr. f. Wissens, xxv, 1891, pp. 26–112, 2 Taf.)
=Bordas, L.= Sur l’appareil venimeux des Hyménoptères. (Comtes rend.,
cxviii, 1894, pp. 296–299 and 873–874; also Zool. Anzeiger, xvii
Jahrg., 1894, pp. 385–387, Figs.)
—— Appareil glandulaire des Hyménoptères. (Glandes salivaires; Tubes
de Malpighi et glandes venimeuses.) Paris, 1894, pp. 362, 11 Pls.
—— Description anatomique et étude histologique des glandes à venin
des insectes Hyménoptères. Paris, 1897, pp. 53, 2 Pls.
See Forel (p. 186); also the standard authors, Kolbe, etc.; also Locy
(Amer. Nat., xviii, 1884, p. 355), Nagel (p. 324), Fenger.
_c._ Wax-glands
=Brandt und Ratzeburg.= Medicinische Zoologie, ii, 1830, p. 179. Taf.
xxv, Fig. 18.
=Treviranus, George R.= Ueber die Bereitung des Wachses durch die
Bienen. (Zeitschrift für Physiologie, etc., iii, 1832, pp. 62, 225.)
=Dufour, L.= Note anatomique sur la question de la production de la
cire des abeilles. (Comptes rend. Acad. Sc., Paris, 1843, xvii, pp.
809–813, 1248–1253; Revue Zool. 1843, l’Institut, 1843, xi.)
=Dujardin, F.= Mémoire sur l’étude microscopique de la cire, etc.
(Ann. Sc. Nat., xii, 1849, pp. 250–259.)
=Tarzione-Tozzetti, H.= Studii sulle cocciniglie. Milano, 1867, 7 Pls.
—— Sur la cire qu’on peut obtenir de la cochenille du figuier (_Coccus
caricæ_). (Comptes rend. Acad. Sc., Paris, lxv, 1867, pp. 246–247.)
=Claus, C.= Ueber die wachsbereitenden Hautdrüsen der Insekten.
(Sitzungsber. Gesells. z. Beförd. d. Gesammt. Naturw. zu Marburg,
June, 1867, No. 8, pp. 65–72.)
=Witlaczil, E.= Die Anatomie der Psylliden. (Zeitschr. wissens. Zool.,
xlii, 1885, pp. 582–586.)
—— Zur Morphologie und Anatomie der Cocciden. (Zeitschr. wissens.
Zool., xliii, 1886, pp. 149–174, 1 Taf.)
=Ihering, H. von.= Der Stachel der Meliponen. (Ent. Nachrichten, xii
Jahrg., 1886, p. 185.)
=Carlet, G.= Sur les organes sécréteurs et la sécrétion de la cire
chez l’Abeille. (Comptes rendus, cx, pp. 361–363, 1890.)
—— La cire et ses organes sécréteurs. (Le Naturaliste, 1890, pp.
149–151, 2 Figs.)
Also the works of Siebold, Cheshire, Kolbe, Howard and Marlatt (Bull.,
3, N. S., Div. Ent. U. S. Dept. Agr., 1896, p. 40), Knaggs, Berlese.
_d._ Wax-like glands of Aphides
=Huber et Forel, A.= Études myrmécologiques, 1875.
=Witlaczil, E.= Zur Anatomie der Aphiden. (Zool. Anzeiger, v Jahrg.,
1882, pp. 239–241; Arbeiten a. d. Zool. Institut der Univ. Wien.,
iv, 1882, pp. 397–441, 3 Taf.)
=Busgen, M. J.= Der Honigtau. Biol. Studien an Pflanzen u.
Pflanzenlause. (Jena. Zeitschrift, xxv, 1891, pp. 339–428.)
DEFENSIVE OR REPUGNATORIAL SCENT-GLANDS
While these eversible glands are not found in marine or aquatic
arthropods such as Crustacea or Merostomata (Limulus), they are often
present in the air-breathing forms, especially insects. In the winged
insects they are of frequent occurrence, existing under great variety of
form, varying greatly in position, and appearing usually to be in
immediate relation with their active volant habits. Their presence is in
direct adaptation to the needs and habits of their possessors, and being
repellent, warning, or defensive structures, the odors they secrete
being often exceedingly nauseous, they appear to have been called into
existence in direct response to their biological environment. The fact
that these singular organs do not exist in marine or aquatic Crustacea
suggests that the air-breathing, aërial, or volant insects by these
eversible glands, usually in the form of simple evaginable hypodermic
pouches, are enabled to protect themselves by emitting an infinitesimal
amount of an offensively odorous fluid or ether-like spray which charges
the air throughout an extent of territory which may be practically
illimitable to the senses of their enemies. The principle is the same as
in the mephitic sulphuretted oil ejected by the skunks, the slight
quantity these creatures give out readily mixing with and charging the
atmosphere within a radius of many miles of what we may call the centre
of distribution.
As is now well known, the very delicate, attenuated highly volatile
odors exhaled are perceived by insects with extreme ease and rapidity,
the degree of sensitiveness to such scents being enormously greater than
in vertebrates, their organs of sense being developed in a corresponding
degree. Professors Fischer and Penzoldt, of Erlangen, have recently
established the fact that the sense of smell is by far the most delicate
of the senses. They find that the olfactory nerve is able to detect the
presence of 1⁄2,760,000,000 of a grain of mercaptan.[58] The smallest
particle of matter that can be detected by the eye is sodium, when
observed by the spectroscope, and this particle is 250 times coarser
than the particle of mercaptan which can be detected by the human nose.
In those Arachnida which are provided with poison-glands, these
scent-glands are absent, but in certain Acarina and Linguatulidæ,
which have no poison-glands, there are various oil-glands, stigmatic
glands, as well as scent-glands, and in seizing a Thelyphonus with
the forceps we have observed it to send out from each side of the
body a jet of offensive spray.
We not infrequently find in myriopods (Polydesmidæ, Julidæ, and
Glomeris) repugnatorial or the so-called cyanogenic glands, which
are either paired, opening on the sides of the body, or form a
single row along the median line of the under side of the body.
Leidy describes and figures the spherical glands of _Julus
marginatus_, of which there are 50 pairs. These glands have been
regarded as modified nephridia, but are more probably coxal glands,
and the homologues of the parapodial glands of annelid worms.
[Illustration:
FIG. 358.—Sternite of _Machilis maritima_, with the pair of coxal sacs
(_cb_) on the right side everted; _hs_, coxal appendages; _m_,
retractor muscles.—After Oudemans, from Lang.
]
=Eversible coxal glands.=—True coxal glands occur in _Scolopendrella
immaculata_ on the 2d to 11th segment, on the inner side of the base of
the legs (Fig. 15, _c.g._). Homologous glands also occur in the same
position in _Campodea staphylinus_ (also in _C. cookei_ and _C.
mexicana_) on the 1st to 8th abdominal segments, and Oudemans has
described a pair of eversible sacs on each side of segments one to seven
of Machilis. These eversible sacs in the synapterous insects are
evidently modified coxal glands, and are probably repugnatorial as well
as respiratory in function.
The apparatus consists of an eversible gland, composed of hypodermic
cells, usually retracted by a slender muscle and with an efferent
passage, but the glands vary greatly in shape and structure in different
insects. In some cases these fœtid glands appear not to be the
homologues of the coxal glands, but simply dermal glands.
These repugnatorial glands are of not infrequent occurrence in the lower
or more generalized winged insects, and in situation and appearance are
evidently the homologues of the coxal glands of the Symphyla and
Synaptera.
_Fœtid glands of Orthoptera._—In the ear-wigs (Forficula and Chelidura)
Meinert has detected a pair of what he calls fœtid glands at the
posterior margin of the dorsal plates of the 2d and 3d abdominal
segments.
Vosseler also describes the same glands as consisting of a retort-shaped
sac, in whose walls are numerous small hypodermal cells and large single
glandular cells provided with an efferent passage, the fluid being
forced out by the pressure of the dermal muscles, one acting specially
to retract the gland. The creature can squirt to a distance of 5 and
even 10 cm. (4 inches) a yellowish-brown liquid or emulsion with the
odor of a mixture of carbolic acid and creosote.
The large eversible dorsal glands of the Blattidæ, since they contain
numerous hairs, which, when everted, are fan-like or like tufts, serve,
as in the spraying or scent apparatus, to disseminate the odor, and
might be classified with the alluring unicellular scent-glands or
_duftapparat_ of other insects, as they are by some authors; but as the
glands are large and compound they may prove to be the homologues of the
coxal glands rather than of the dermal glands.
Evaginable organs in the Blattids were first observed by Gerstæcker in
both sexes of Corydia; they are yellowish white, covered with hairs, and
are thrust out from between the dorsal and ventral plates of the 1st and
2d abdominal segments.
[Illustration:
_Fig. 359._—Under side of end of Aphlebia, showing the two eversible
sacs; _V-X_, five last abdominal segments; _A_, portion showing the
hairs; _B_, showing origin of a hair in its follicle.—After Krauss.
]
In the cockroach (_P. orientalis_) Minchin detected two pouch-like
invaginations of the cuticle, lying close on each side of the middle
line of the body between the 5th and 6th tergites of the abdomen. They
are lined by a continuation of the cuticle, which forms, within the
pouches, numerous stiff, branched, finely pointed bristles, beneath
which are a number of glandular epithelial cells. In the male nymph of
_P. decorata_ he also found beside these glandular pouches “an
additional gland, opening by a tubular duct under the intersegmental
membrane between the 5th and 6th terga above the glandular pouch of each
side, and extending forward into the body cavity. The gland and its duct
are proliferations of the hypodermis, and there is no invagination of
the cuticle.” These eversible glands are most complicated in
_Phyllodromia germanica_. While it is absent in the female, in the male
it is relatively of enormous size, extending over the 6th and 7th
somites, as well as projecting far into the body cavity (Minchin). Haase
states that these glands become everted by blood-pressure and give out
the well-known disagreeable smell of these insects. He states that in
the male of _P. germanica_ the dorsal glands in the 6th and 7th
abdominal segments are without hairs and produce an oily secretion; they
function as odoriferous organs in sexual union.
In the male of another Blattid (_Aphlebia bivittata_) of the Canary
Islands, Krauss has detected two yellowish dorsal sacs 1.5 mm. in
length, opening out on the 7th abdominal segment, and filled full of
long yellowish hairs, the ends directed towards the opening, where they
form a thick tuft. These eversible glands lined with hairs appear to be
closely similar to the long slender eversible hairy appendages or scent
organs of certain Arctian and Syntomid moths. (Fig. 359.)
[Illustration:
FIG. 360.—External flaps (_gl_) of glands of Platyzosteria.
]
We have found the external median wart with lateral lids or flaps in
between the 5th and 6th tergites of _Platyzosteria ingens_ Scudder, a
large wingless Blattid living under the leaf scars of the cocoanut tree
in Southern Florida (Fig. 360), but were unable to detect them in
Polyzosteria or in the common Blabera of Cuba, or in another genus from
Cordova, Mexico.
In another group of Orthoptera, the Phasmidæ, occur a pair of dorsal
prothoracic glands, each opening by a pore and present in both sexes. In
the walking-stick, _Anisomorpha buprestoides_, ♂ and ♀, these openings
are situated on each side of the prothorax at its upper anterior
extremity, situated at the bottom of a large deep pit. When seized it
discharged a “milky white fluid from the pores of the thorax, diffusing
a strong odor, in a great measure like that of the common Gnaphalium or
life everlasting” (Peale in Say’s American Entomology, i, p. 84). Boll
states that the females when captured “spurt from the prothorax,
somewhat after the manner of bombardier beetles, a strong vapor, which
slightly burnt the skin; when the females were seized by the males a
thick fluid oozed from the same spot.” Scudder describes these glands in
another Phasmid (_Autolyca pallidicornis_) as two straight, flattened,
ribbon-like bodies, with thick walls, broadly rounded at the end, lying
side by side and extending to the hinder end of the mesothorax. In
_Anisomorpha buprestoides_ the glands are of the same size and shape
(Scudder). In _Diapheromera femorata_ the repugnatorial foramina are
very minute, and the apparatus within consists of a pair of small
obovate or subfusiform sacs, one on each side of the prothorax, about 1
mm. in length, with a short and very slender duct opening externally at
the bottom of the pit (Scudder).
In the Mantidæ these seem to be genuine coxal glands, as there is a pair
situated between the coxæ of the first pair of legs. An evaginable organ
like a wart, with a glandular appearance, occurs on the hind femora of
the Acrydiidæ in a furrow on the under side, into which the tibia fits,
about one-fourth from the base (Psyche, iii, p. 32).
In the male cricket, the anal odoriferous glands are small lobes opening
into a reservoir on each side of the rectum (Dufour). Homologous glands
also occur in the Coleoptera (Fig. 302, _l_ and 317, _s_).
[Illustration:
FIG. 361.—Glands (_g_) of Lachnus; _h_, “honey” wart.—Gissler _del._
]
Most Hemiptera or bugs send out a fœtid or nauseous odor due to a fluid
secreted by a single or double yellow or red pear-shaped gland, situated
in the middle of the mesothoracic segment, and opening between the
hinder or third pair of coxæ. In Belostoma Leidy describes these glands
as consisting of two rather long cœcal tubes situated in the metathorax,
beneath the other viscera, extending backwards into the abdomen, and
opening between the coxæ of the third pair of legs. Locy states that the
smell arising from these glands is pleasant, resembling that of well
ripened pears or bananas. Other bugs, moreover, emit an agreeable odor,
that of Syromastes resembling that of a fine bergamot pear. (Siebold.)
The fluid given out by the European fire-bug (_Pyrrhocoris apterus_) has
a sweetish smell, like ether. In the nymph there are three pairs of
dorsal glands, on abdominal segments 2–5, which are atrophied in the
mature insect. In the bed-bug, the nymph has three odoriferous glands
each with paired openings in the three basal abdominal segments
respectively, and situated on the median dorsal line, being arranged
transversely at the edge of the tergites; but after the last moult these
are aborted, and replaced by the sternal metathoracic glands (Künckel).
Gissler has detected a pair of glands in _Lachnus strobi_ (Fig. 361).
=Anal glands of beetles.=—Certain beetles are endowed with eversible
repugnatorial glands. _Eleodes gigantea_ and _E. dentipes_ of both sexes
are said by Gissler to possess these glands. When teased “they stand on
their anterior and middle legs, holding the abdomen high up and spurting
the contents of the glands right and left.” The glands (Fig. 366, 1) are
two reddish brown, somewhat bilobed sacs, and extend from the base of
the last up to the middle of the 2d abdominal segment, with an average
length of 6.5 mm. The liquid stains the human skin, has an acid
reaction, with a peculiar, “intensely penetrant odor, causing the eye to
lachrymate. It is soluble in water, alcohol, and ether. Boiled with
concentrated sulphuric acid and alcohol an ethereal aromatic vapor is
produced, indicating the presence of one or more organic acids, though
neither formic or acetic acid could be detected.” Williston has observed
the same habits in seven other species of Eleodes, all ejecting a
pungent vile-smelling liquid, one species (_E. longicollis_) ejecting a
stream of fluid from the anal gland, backwards sometimes to the distance
of 10 cm. or more, and he regards these beetles as “the veritable skunks
of their order.” Leidy briefly describes the odoriferous glands of _Upis
pennsylvanica_.
The anal glands consist, according to Meckel and also Dufour, of two
long, simple, flexuous cœca with reservoirs having two short excretory
ducts situated near the anus (Siebold).
Glands like those of Eleodes found in _Blaps mortisaga_ are described in
detail by Gilson (Fig. 366, 2). They form two pouches or cuticular
invaginations situated in the end of the abdomen on the sides of the end
of the intestine and unite on the median line underneath the genital
organs, forming a very short tube with a chitinous wall, continuous with
the cuticle of the last abdominal segment. Into each pouch open a large
number of fine slender lobules varying in shape, giving a villous aspect
to the surface. These lobules are composed of as many as fifty
unicellular glands, each of which is composed of four parts: (1) A
radiated vesicle, (2) a central sac, giving rise (3) to a fine excretory
tube, and (4) a sheath near the origin of the excretory tube. These are
all modifications of the cytoplasm of the cell with its reticulum; the
nucleus with its chromosomes is also present, but situated on one side
of the central sac. The fine excretory tubules form a bundle passing
down into the mouth of each lobule.
Similar glands, though usually smaller, which have not been
carefully examined, occur in Carabus (Fig. 300, 3) and Cychrus,
which eject from the vent a disagreeable fluid containing butyric
acid (Pelouse). The bombardier beetle Brachinus, with its anal
glands, ejects a jet of bluish vapor accompanied with a considerable
explosion, which colors the human skin rust red; it is caustic,
smells like nitrous acid, and turns blue paper red. Westwood states
that individuals of a large South American Brachinus on being seized
“immediately began to play off their artillery, burning and staining
the flesh to such a degree that only a few specimens could be
captured with the naked hand, leaving a mark which remained for a
considerable time.” The fluid ejected by another species, in
Tripoli, blackened the fingers of the collector. “It is neither
alkaline nor acid, and it is soluble in water and in alcohol.”
(Kirby and Spence, iv, p. 149.)
Species of other genera (Agonum, Pheropsophus, Galerita, Helluo,
Paussus, Ozæna) are also bombardiers, though less decidedly so than
Brachinus. A Paussid beetle (Cerapterus) ejects explosively a fluid
containing free iodine (Loman), while Staphylinus, Stenus, Ocypus
olens, Lacon, etc., have similar anal fœtid glands, the liquid being
more or less corrosive. The secretion of _Mormolyce phyllodes_ is so
corrosive that it is said to paralyze the fingers for 24 hours
after. (Cuénot.)
[Illustration:
FIG. 362.—Median section through the femoro-tibial joint of leg of
Coccinella, showing at _o_ the opening through which the blood oozes
out; _f_, femur; _t_, tibia; _e_, extensor muscle of the tibia: _s_,
sinew of the same; at _ch_, chitinized; _h_, articular membrane;
_v_, tibial process.—After Lutz.
]
The two pairs of remarkably large, soft, eversible, forked,
orange-yellow glands of the European genus Malachius, are thrust out
from the side of the 1st and the 3d thoracic segments. They are everted
by blood-pressure, and retracted by muscles. The larva of _Hydrophilus
piceus_ ejects by the anus a black, fœtid fluid.
Claus has shown that the larva of _Lina populi_ and other Chrysomelidæ
possess numerous minute, eversible glands in each of the warts on the
upper surface of the body, each gland containing a whitish, repellent
fluid smelling like the oil of bitter almonds and containing salicylic
acid derived from its food-plant, which issues as pearl-like drops.
Candèze thinks the fluid may contain prussic acid. The fluid is secreted
by a variable number of glandular cells, each provided with an efferent
duct. The larvæ of saw-flies, notably _Cimbex americana_, also eject
droplets of a clear fluid from non-evaginable glands situated near each
stigma (Chlolodkovsky).
=The blood as a repellent fluid.=—In this connection it may be mentioned
that though there are no special glands present, many beetles emit drops
of blood from the femoro-tibial joints of their legs as a means of
defence. Such are the oil-beetles (Meloë), Cantharis, Lytta. The
cantharadine secreted by these beetles, according to Beauregard, is an
efficient means of defence, as birds, reptiles, and carnivorous insects
will not usually attack them. This substance is formed in the blood and
also in the genital organs, and is so extremely caustic that scavenger
insects which feed upon their dead bodies will leave untouched the parts
containing cantharadine, and if May-beetles or mole-crickets are washed
with the blood of Meloë or with cantharidate of potassa, it will for
several days render them safe from the attacks of the carabids which
usually prey upon them. The eggs even after deposition are strongly
vesicant, and are thus free from the attacks of egg-eating insects
(Cuénot). The Coccinellidæ are also protected by a yellow, mucilaginous,
disagreeable fluid oozing out of the ends of the femora; in our common,
two-spotted lady-bird (_C. bipunctata_) the yellow fluid is
disagreeable, smelling like opium. Lutz has found that the blood in
Coccinellidæ passes out through a minute opening situated at the end of
each femur (Fig. 362). The blood is very repellent to insectivorous
animals.
The Dyticidæ eject from the anus a colorless, disagreeable fluid, while
these beetles, and especially the Gyrinidæ, when captured send out a
milky fluid which appears to issue from the joints of the body. The
Silphidæ throw out both from the mouth and vent a fœtid liquid with an
ammoniacal odor. They possess but a single anal gland, the reservoir
opening on one side of the rectum (Dufour).
Other malodorous insects have not yet been investigated; such are the
very persistent odors of lace-winged flies (Chrysopa).
More agreeable secretions, but probably formed by similar glands, is the
odor of rose or hyacinth given out by Cicindelæ, or the rose fragrance
exhaled by the European _Aromia moschata_.
=Eversible glands of caddis-worms and caterpillars.=—Gilson, while
investigating the segmentally disposed thoracic glands of larval
Trichoptera, has found in the larva of _Limnophilus flavicornis_ that
the sternal prothoracic tubercle gives exit to an underlying tubular
gland. In _Phryganea grandis_ each thoracic sternum affords an exit to
an eversible gland. Many caterpillars, as our subjoined list will show,
are very well protected by eversible repugnatorial glands situated
either in the under or upper side of the body. Since the time of De Geer
(1750) the fork-tailed larva of Cerura has been known to throw out a
secretion, which was described by Bonnet in 1755 as a true acid, sharp,
sour, and biting. This spraying apparatus in _Cerura (Harpyia) vinula_
has been well described by Klemensiewicz (Fig. 366, 4), though Rengger
in 1817 noticed the general form of the secretory sac, and that it opens
out in two muscular eversible tubes, out of which the secretion is
ejected.
The fork-tailed larva of _Macrurocampa marthesia_, which is much like
that of Cerura, when teased sends out a jet of spray to the distance of
nearly an inch from each side of the neck. While examining the very
gayly-colored and heavily-spined caterpillars of _Schizura concinna_ we
observed that when a fully-grown one was roughly seized with the forceps
or fingers it sent out a shower of spray from each side of the
prothoracic segment, exactly like that of Cerura and Macrurocampa.
In the European _Cerura vinula_ the apparatus consists of a single sac,
which opens by a narrow transverse slit on the under side of the neck,
out of which is rapidly everted four lateral tubes, two on each side
(Fig. 366, 4, _t_), which are withdrawn within the opening by the
contraction of several fine muscles. The apparatus in the American _C.
multiscripta_ is as in the European _C. vinula_. In a living specimen
the large secretory sac was seen to be of the same size and shape as in
Macrurocampa, and of the color of raw silk. The sac when distended
extends back to a little behind the middle pair of legs, and is nearly
two-thirds as wide as the body. The caterpillar sent out the fluid when
handled, but we could not make it spray.
In the larva of _Macrurocampa marthesia_ the cervical or secretory gland
(Fig. 366, 5) is situated in the 1st and 2d thoracic segments, extending
to the hinder edge of the latter and lying between the nervous cord and
the œsophagus and proventriculus, and when empty the bulk of it lies a
little to one side of the median line of the body. It is partly held in
place by small tracheæ, one quite large branch being sent to it from
near the prothoracic spiracle. The short, large duct, leading from it to
the transverse opening in the membrane between the head and prothoracic
segment, is a little narrower than this opening, and is kept distended
by tænidia, or a series of short, spiral threads which are pale, not
honey-yellowish, in color. This duct lies on one side of the prothoracic
ganglion, resting just under the commissures passing up to the brain; it
is also situated between the two silk ducts.
The very distensible sac (Fig. 366, 5) is rendered elastic by a curious
arrangement of the cuticle, the tænidia of the duct itself being
represented by very thickly-scattered, irregular, separate, sinuous,
chitinous ridges, which stand up from the cuticular lining of the wall
of the sac (Fig. 366, 6). The secretory cells of the walls of this sac
in _Cerura vinula_ are said by Klemensiewicz to be large hexagonal
cells, resembling those of silk-glands, having like them large branched
nuclei.
The fluid thrown out is said by Poulton to be formic acid; it causes
violent effervescence when allowed to fall upon sodium-bicarbonate, and
colors blue litmus paper red. It also appears from the researches of
Latter that these creatures in the imago state secrete free potassium
hydroxid, a substance for the first time known to exist in the animal
kingdom.
In the caterpillar of _Astyanax archippus_ (_Limenitis disippus_) a
dark, bladder-like sac is everted, but the lateral tubes appear to be
wanting, and no spray is sent out; it occurs in the larvæ of many
Nymphalidæ and other butterflies and moths.
These glands are functionally active in Perophora, but obsolete (at
least the external openings) in Lacosoma.
=The osmeterium in Papilio larvæ.=—The caterpillars of the swallowtailed
butterflies (Papilio, Doritis, and Thais), as is well known, when
irritated thrust out from a transverse slit on the upper part of the
prothoracic segment a large orange-yellow V-shaped fleshy tubular
process (the osmeterium), from which is diffused a more or less
melonlike but disagreeable, in some cases insufferable, odor; the
secretion is acid and reddens litmus paper. The mechanism has been
described and figured by Klemensiewicz.
When at rest, or retracted, the osmeterium lies in the upper part of the
body in the three thoracic segments, and is crossed obliquely by several
muscular bundles attached to the walls of the body, and by the action of
these muscles the evagination of the osmeterium is strongly promoted.
After eversion the tubes are slowly retracted by two slender muscles
inserted at the end of each fork or tube, and arising from the sides of
the 3d segment behind the head, crossing each other in the median line
(Fig. 366, 7 _r.m._). The secretion is formed by an oval mass of
glandular cells at the base of the forks; in the glandular mass is a
furrow-like depression about which the secretory cells are grouped. The
secretion collects in very fine drops on the side of each furrow
opposite the glandular cells.
According to C. D. Ash the larva of an Australian Notodontid (_Danima
banksii_ Lewin) protrudes from the under side of the prothoracic segment
a Y-shaped red organ like that of Papilio; no fluid or odor is given
out.
=Dorsal and lateral eversible metameric sacs in other larvæ.=—The showy
caterpillars of Orgyia and its allies have a conspicuous coral-red
tubercle on the back of the 6th and also the 7th abdominal segment,
which on irritation are elongated, the end of the tubercles being
eversible. When at rest the summit is crateriform, but on eversion the
end becomes rounded and conical. These osmeteria are everted by blood
pressure, and retracted by a muscle. Fig. 366, 9, represents a section
of an osmeterium of _Orgyia leucostigma_ when retracted by the muscle
(_m_); at the bottom of the crater are the secreting or glandular cells
(_gc_), being modified hypodermal cells. These doubtless serve as
terrifying organs to ichneumons and other insect enemies, and though we
have been unable to detect any odor emanating from the tubercles, yet
possibly they give out a scent perceived by and disagreeable to their
insect assailants.
[Illustration:
FIG. 363.—Freshly hatched larva of _Hyperchiria io_, with its two
pairs of eversible glands (_g_).
]
[Illustration:
FIG. 364.—Young larva of _Megalopyge crispata_, enlarged, showing the
seven pairs of lateral processes (_lp_): _sp_, spiracle; _abl′_,
_abl^6_, six pairs of abdominal legs besides the anal pair.
]
In the Hemileucidæ there is a pair of lateral osmeteria, on the 1st and
on the 7th abdominal segments, which however, are not highly colored
(Figs. 363, 366, 10). In Megalopyge (Lagoa, Fig. 364) there is a lateral
row of singular pale permanently everted processes which appear to be
the homologues of the osmeteria of larvæ of other lepidopterous
families. As these are repeated on seven segments, their metameric
arrangement is obvious. The relation of these curious glands to the
viscera is seen in Fig. 297, _lgp_, and their minute structure in Fig.
365.
At _A_, the lumen (_l_) is a deep narrow cavity, with the secretion
(_secr._), collected at the mouth of the cavity, composed of a thin,
mucus-like, coagulated fluid, containing granules of varying degrees
of fineness, which take the stain readily. Outside of these are
collected fine nuclei (_bc_), stained dark, and enveloped in a
slight, transparent, pale, protoplasmic envelope, which may be blood
corpuscles. The glandular cells themselves are simply modified
hypodermal cells, as seen at _C_. In some of the nuclei, indistinct
nucleoli are seen, and deeply stained granules, especially around
the periphery of the nuclei. At _B_ is represented a section on one
side of the middle, but still showing the spacious lumen. In the
section represented by _C_, the knife passed through the process
still nearer the outer edge, and near the base; at _C^1_, three of
the glandular cells, with their large, deeply stained nuclei, are
drawn. A transverse section at _D_ shows the large lumen or cavity
(_l_).
As to the function and homologies of these structures, it is
difficult to decide. We have never noticed that they give off any
odor, though they may prove to be repugnatorial; they are not
visible in the fully grown, living insect, being concealed by the
long, dense hairs clothing the body; they are not spraying organs,
as they are imperforate at the end, not ending as the lateral,
eversible glands of _Hyperchiria io_, etc., in a crateriform
orifice.
They may be permanently everted glands, or osmeteria, which have, by
disuse, lost their power of retraction and their crateriform
opening, as well as the power of secreting a malodorous fluid.
[Illustration:
FIG. 365.—Section of lateral processes of larva of Megalopyge.
]
In certain of the butterflies, the Heliconidæ (Colænis, Heliconius,
Euides, and Dione), there is thrust from the end of the abdomen a pair
of large, irregular, rounded, eversible glands, which give out a
disagreeable odor, and are consequently repellent, and which seem to be
the homologues of the odoriferous glands of other butterflies.
The large, soft, rounded, eversible glands, looking like puff-balls
or a rounded pudding (Fig. 366, 12), are everted, when the
butterflies are roughly seized, from the dorsal side of the
penultimate segment of the abdomen. The males possess two smaller
tubercles on the inside of the anal claspers or lobes. Müller also
detected, in the females of various species of the Heliconidæ
enumerated above, a pair of club-shaped processes like the balancers
of flies, which are thrust out on each side of and under the
odoriferous puff-balls of the hinder edge of the penultimate segment
(Fig. 366, 13). The club or head is armed with hairs or bristles,
which, in Heliconius, are like the scales of a butterfly.
[Illustration:
FIG. 366.—Scent-glands of insects: 1. Anal eversible glands of
Eleodes.—After Gissler. 2. Anal eversible glands of Blaps.—After
Gilson. 3. Anal glands (_agl_) of _Carabus hortensis_: _rs_,
reservoir; _d_, excretory duct; _i_, intestine; _r_, rectum.—After
Kolbe. 4. Prothoracic spraying apparatus of _Cerura vinula_: _gl_,
the gland; _d_, its duct, with tænidia; _t_, the spraying tubes;
_m_, muscles; _rm_, retractor muscles.—After Klemensiewicz. 5. The
thoracic glandular sac of _Macrurocampa marthesia_: _gl_, the
glandular sac; _d_, its duct; _e_, peritracheal epithelium; _t_, the
spiral threads or tænidia. 6. Irregular separate masses of chitinous
ridges on the cuticular lining of the wall of the sacs of
_Macrurocampa marthesia_. 7. Osmeterium (_os_) of the larva of
_Papilio machaon_ at rest: _rm_, the retractor muscles at the ends;
_m_, the numerous oblique muscles; _dm_, dorsal longitudinal
muscles; _t_, trachea; _oe_, œsophagus; _gang_, brain; 1, head; 2,
3, 4. thoracic segments. 8. Osmeterium (_os_) of one side, enlarged:
_g_, glandular portion at the base; _d_, depressions in the cuticula
of the glandular portion; _t_, trachea.—This and Fig. 7 after
Klemensiewicz. 9. Eversible dorsal glands (_ev. gl_) of larva of
_Orgyia leucostigma_ in Stage II: _gc_, glandular cells at bottom of
the crater-like depression; _m_, retractor muscle; _p_, poison
gland-cells of the root of the seta (_s_); _c_, cuticula; _hyp_,
hypodermis; _A_, portion of the cuticle and hypodermis enlarged. 10.
Lateral eversible gland of _Hyperchiria io_, Stage II: _rm_,
retractor muscle; _oen_, œnocytes. 11. The same as Fig. 10, but
representing a section through one side of the eversible gland. 12.
_A_, end of body of _Colænis julia_; _ev_, eversible anal gland;
_oa_, odoriferous appendages; _B_, the same in _Heliconius
apseudes_, side view; _C_, odoriferous appendages of _Colænis dido_
in fresh condition; _D_, tested with alcohol and benzine. 13.
Odoriferous appendages of _Heliconius eucrate_, head cleansed.—Figs.
12, 13, after F. Müller. 14. Odoriferous glands (_ogl_) in the pupa
of _Vanessa io_: _r_, rectum; _h_, the folds of hypodermis which
forms the terminal papilla of the abdomen; _ov_, oviduct.—After
Jackson.
]
In the caterpillars of certain blue butterflies (Lycænidæ) is an
internal osmeterium, being a very minute sac which is everted from a
transverse slit on the top of the 7th abdominal segment. Its function is
quite the opposite of those of the caterpillars of other families, since
the sac exudes a sweet fluid very attractive to ants, which may be
diffused more widely by the delicate spinulose bristles crowning the
summit. W. H. Edwards states that in several species of Lycæna, besides
that on the 7th abdominal segment, there is on the 8th segment a pair of
minute dorsal evaginable tubercles.
A pair of small ramose odoriferous glands are said by Siebold, who
regarded them as alluring glands, to occur in Argynnis, Melitæa, and
Zygæna, to be situated near the orifice of the oviduct, and Scudder has
detected them near the anus of the female pupa of _Danais archippus_.
The appearance of the odoriferous glands in the pupa of _Vanessa io_ is
well shown by Jackson (Fig. 366, 14). They develop as two tubular
ingrowths of the hypodermis, perfectly distinct one from the other, each
having its own separate aperture to the exterior. In Fig. 366, 14 the
condition of parts is nearly as in the imago, the glands being situated
below the rectum and opening of the oviduct. In both sexes of another
Brazilian butterfly (_Didonis biblis_) on the median line of the abdomen
between the 4th and 5th segments are two roundish vesicles covered with
short gray hairs, which emit a disagreeable smell.
It is possible that the dark-green fluid in Parnassius, secreted by
an evaginable gland, and which is moulded into shape by the
scimetar-shaped peraplast (Scudder), is formed by the homologues of
the anal glands of other butterflies.
Distribution of repugnatorial or alluring scent-glands in insects[59]
_A._ LARVAL INSECTS
_a._ _Each thoracic segment; sternal. Phryganea grandis._
_b._ _Prothoracic, sternal, discharging a lateral jet of spray; with a
single large internal sack._
LEPIDOPTERA
Family TINEIDÆ
_Hyponomeuta evonymella._
Family NOCTUIDÆ
_Bryophila_, _Cucullia formosa_, _C. scrophulariæ_, _Habrostola_,
_Cleophana linariæ,_ Catocala (sp.), _Aporia cratægæ_, _Aplecta
nebulosa_, _Leucania staminea_, _L. hispanica_, _L. nonagrioides_,
_Plusia gamma_.
Family NOTODONTIDÆ
_Pheosia rimosa_, _Schizura concinna_, _Danima Banksii_ (Australia),
_Macrurocampa marthesia_, _Heterocampa pulverea_, _Cerura vinula_, _C.
furcula_, _C. borealis_, _C. multiscripta._
Family NYMPHALIDÆ
Probably all the species.
_c._ _Prothoracic, dorsal; sending out a_ V-_shaped odoriferous organ_
(osmeterium).
Family PAPILIONIDÆ
All the species as a rule.
_d._ _Thoracic sternal, evaginable glands._
Family PEROPHORIDÆ
_Lacosoma chirodota_, _Perophora melsheimerii_.
Family NOLIDÆ
In three, and probably in all the species of Nola.
_e._ _Lateral, abdominal, non-eversible glands, one near each spiracle,
emitting a clear fluid._
Family TENTHREDINIDÆ
_Cræsus septentrionalis_, _C. varus_, _Cimbex americana_, _C. betulæ,
Trichiosoma_.
_f._ _Lateral, abdominal, partly eversible glands emitting neither
moisture nor odor, but flesh-colored._
Family _Tineidæ_
Phyllocnistis? (eight pairs.)
Family HEMILEUCIDÆ
_Hyperchiria io_ (two pairs, viz. on 1st and 7th segments), _H._ sp.
(Mexico), _Hemileuca yavapai_, _pamina_, _H. maia_, _H. artemis_,
_Pseudohazis eglanterina_.
_g._ _Lateral, abdominal, permanently everted, metameric glands, not
known to secrete a fluid, nor to be odoriferous._
Family MEGALOPYGIDÆ
_Megalopyge crispata._
_h._ _Medio-dorsal, partly eversible glands, emitting a spray of liquid
but no odor(?), and colored coral-red or orange-yellow (P. auriflua),
but usually in the European species yellowish._
Family LIPARIDÆ
All the species except those of Demas.
_i._ _A single, median, abdominal, dorsal gland, emitting a fluid
attractive to ants, on 7th segment; with a pair of minute, index glands
on the 8th segment._
Family LYCÆNIDÆ
All the species.
_j._ _Protrusile organs near the anus._
_Myrmeleon_ larva (Hagen? Dimmock).
_B._ NYMPH OF HETEROMETABOLOUS INSECTS
_a._ _Paired, dorsal glands, on abdominal segments 1, 2, and 3._
_Cimex lectularius_ (Künckel).
_b._ _The same on abdominal segment 5._
_Lachnus strobi._
_C._ PUPA OF CERTAIN BOMBYCES
_At anterior end of certain pupæ, internal glands to moisten threads of
the cocoon for exit of moth._
_D._ ADULT INSECTS
_a._ _Occurring on the prothorax only; strongly repugnatorial, best
developed in_ ♂.
_Anisomorpha buprestoides_, _Autolyca pallidicornis_, _Phasma putidum_,
_Phyllium_ (sp.), _Heteropteryx_ (sp.), _Diapheromera femoratum_
(probably in all the species of the family), _Mantis carolina_.
_b._ _Occurring on the pro- and mesothorax, and on the middle of the
abdomen, orange-yellow, fleshy tubercles or evaginations._
_Malachius bipustulatus_, _Anthocomus equestris_, _Evæus thoracicus_.
_c._ _Segmental, eversible glands, homologues of the coxal glands of
other Arthropods, occurring on all, or nearly all, the abdominal
segments._
_Scolopendrella immaculata_ (coxal glands on 3d to 11th pair of legs),
_Campodea staphylinus_ (a pair of coxal glands on 1st to 8th abdominal
segments), _Machilis maritima_ (eversible, coxal glands on segments
1–7).
_d._ _Occurring in the abdomen._
_d^1._ _In the two first abdominal segments._
_Corydia carunculigera_ ♂ and ♀.
_d^2._ _Alluring (?) organs situated on the dorsal side of the abdomen,
in the 6th, or 6th and 7th, abdominal segment._
_Periplaneta americana_ ♂, _P. orientalis_ (nymph), _P. decorata_ ♂
(nymph), _Ectoblatta germanica_ ♂, _Ectobia lapponica_ ♂, _Phyllodromia_
♂, _Aphlebia bivittata_ ♂, _Platyzosteria ingens_ (on seventh segment).
_e._ _At the end of the body._
_Colænis julia_ ♀ (F. Müller), _Heliconius apseudes_ (F. Müller).
LITERATURE ON DEFENSIVE OR REPUGNATORIAL GLANDS
=Aldrovandus, U.= De animalibus insectis libri septem cum singulorum
iconibus ad vivum expressis. (Denuo impress: Bonon. apud Clementem
Ferronium, 1638, p. 273. The first edition was in 1602.)
=Moufet, T.= Insectorum sive minimorum animalium theatrum, etc.
London, 1634, pp. 185, 186.
=Gœdart, J.= Metamorphosis naturalis sive insectorum historia, etc.
Amstelodami, 1700, Pars ii, p. 136. (French ed. of 1700, ii, p. 162;
Lister’s Latin ed., London, 1685, p. 60.)
=Réaumur, R. A. F.= Mémoires pour servir à l’histoire des insectes,
etc. Paris, 1736, ii, pp. 266–269, Pls. 21, 22. [ii, partie ii, pp.
21–23, of the Amsterdam ed. of 1737–1748.]
=De Geer, C.= Observation sur la propriété singulière qu’ont les
grandes chenilles à quatorze jambes et à double queue, du saule, de
seringuer de la liqueur. (Mém. sav. étrang, Paris, 1750, i, pp. 530,
531, Pl.; Goetze und Bonnet, etc., Auserlesene Abhandlungen, 1774,
p. 220.)
=Schaeffer, J. C.= Neuendeckte Theile an Raupen und Zweyfaltern, etc.
Regensburg, 1754.
=Sulzer, J. H.= Die Kennzeichen der Insekten, etc. Zürich, 1761, pp.
65–67, Taf. 5, Fig. 34.
=Müller, O. F.= Pile-larven med dobbelt Hale, og dens Phalæne, etc.
Kjöbenhavn, 1772, pp. 53–56, Pl. 2, Figs. 3–5.
=Bonnet, C.= Mémoire sur une nouvelle partie commune à plusieurs
espèces de chenilles. (Mém. math. d. savants étrang., Paris, 1755,
ii, pp. 44–52; Collection complète des œuvres de C. Bonnet, 1779,
ii, pp. 3–16.)
—— Mémoire sur la grande chenille à queue fourchue du saule, dans
lequel on prouve, que la liqueur que cette chenille fait jaillir,
est un véritable acide, et un acide très-actif. (Mém. math, de
savants étrang., Paris, 1755, ii, pp. 267–282; Collection complète
des œuvres de C. Bonnet, 1779, ii, pp. 17–24.)
=Amoreux, P. J.= Notice des insectes de la France, réputés venimeux,
etc. Paris, 1789, pp. 282–285.
=Schwarz, C.= Neuer Raupenkalender. Nürenberg, 1791, Abth. i, p. 59.
=Petzhold, C. P.= Lepidopterologische Beyträge. (L. G. Scriba’s
Beiträge zu der Insekten-geschichte, Frankfurt am Main, 1793, Heft
3, pp. 230–251.)
=Nouvelle Dictionnaire d’Hist. Nat.=, xv, p. 487. (Larva of
Hydrophilus ejects with a slight noise a fœtid and blackish fluid.)
=Rengger, Johann Rudolph.= Physiologische Untersuchungen über die
thierische Haushaltung der Insecten. Tübingen, 1817. (In the chapter
entitled Abgesonderte Säfte bei den Raupen, he speaks of the
glandular apparatus of the larva of _B. vinula_, noticing the
general form of the secretory sac, that it opens out in two muscular
evertible points, out of which the secretion is ejected.)
=Dufour, L.= Mémoire anatomique sur une nouvelle espèce d’insecte du
genre Brachinus. (Ann. de mus. d’histoire nat., xviii, 1811, pp.
70–81.)
—— Recherches anatomiques sur les carabiques et sur plusieurs autres
coléoptères. (Ann. d. Sci. Nat., 1826, viii, pp. 5–54.)
—— Mémoire sur les métamorphosis et l’anatomie de la _Pyrochroa
coccinea_. Glande odorifique. (Ibid., ii sér. Zoologie, xiii, 1840,
pp. 340, 341.)
—— Recherches anatomiques sur les Diptères. 1851, pp. 195, 313.
(Alimentary canal of Sepsis contains the seat of a “glande
odorifique.”)
=Kirby and Spence.= Introduction to entomology, etc. (2d ed., i, 1815;
London, 1818, ii, pp. 238, 239.)
=Lyonet, P.= Recherches sur l’anatomie et les metamorphoses de
différentes espèces d’insectes. Ouvrage posthume. Paris, 1832.
=Morren, C.= Mémoire sur l’émigration du puceron du pêcher (_Aphis
persicæ_), et sur les caractères et l’anatomie de cette espèce.
(Ann. Sci. Natur. Zool., 1836, vi, pp. 65–93, Pls. 6, 7.)
=Ratzeburg, J. T. C.= Die Forstinsekten, etc. (Theil i, Die Käfer,
etc., 1837, p. 246.)
=Aubé, C.= Note sur une sécrétion fétide d’_Eumolpus pretiosus_. (Ann.
Soc. Ent. Fr., 1837, i, vi; Bull., p. 58.)
=Lacordaire, J. S.= Introduction à l’entomologie. 1838, ii, p. 45.
=Meckel, von Hemsbach, Johann Friedrich.= Mikrographie einiger
Drüsenapparate der niederen Thiere. (Anat. Phys. u. wiss. Med.,
1846, pp. 1–73, Taf. 1–3; p. 46, Müller’s Archiv.)
=Stein, Friedrich.= Vergleichende Anatomie und Physiologie der
Insekten. Berlin, 1847.
=Leidy, Joseph.= History and anatomy of the hemipterous genus
Belostoma. (Journ. Acad. Nat. Sci. Philadelphia, Ser. 2, 1847, i,
Part i, pp. 57–67, Pl. 1.)
—— Odoriferous glands of invertebrata. (Proc. Acad. Philadelphia,
1849, iv, 234–236, 1 Pl.; Ann. and Mag. N. H., Ser. 2, 1850, v, pp.
154–156.)
=Chapuis et Candèze.= Catalogue des larves des coléoptères, etc. (Mém.
Soc. Sci. de Liège, 1853, viii, pp. 351–653, Pls. 1–9, pp. 611,
612.)
=Siebold, Carl Theodor.= Lehrbuch der vergleichenden Anatomie der
wirbellosen Thiere, 1848. (Burnett’s transl., Boston, 1854.)
=Burnett, Waldo Irving.= Translation of Siebold’s Anatomy of the
Invertebrates, 1854. (Note on the osmeteria of _Papilio asterias_,
which he regards as an odoriferous and defensive, rather than
tactile, organ, p. 415.)
=Karsten, H.= Bemerkungen über einige shaarfe und brennende
Absonderungen verschiedener Raupen. (Müller’s Archiv für Anat. Phys.
u. wiss. Med., 1848, pp. 375–382, Taf. 11, 12.) Describes the
poison-glands at the base of the spines of Saturnia larvæ.
—— Harnorgane des _Brachinus complanatus_. (Müller’s Archiv, 1848, pp.
367–376, Taf.)
=Laboulbéne, Alexandre.= Note sur les caroncules thoraciques du
Malachius. (Annales de la Soc. Ent. de France, 3^e Sér., vi, 1858,
pp. 521–528.)
=Saussure, Henri de.= Recherches zoologiques de l’Amerique centrale et
du Mexique. (6^e Partie, Études sur les Myriopodes et les Insectes,
Paris, 1860.)
=Gerstaecker, C. E. A.= Ueber das vorkommen von ausstülpbaren
Hautanhängen am Hinterleibe an Schaben. (Archiv f. Naturgesch.,
1861, xxi, pp. 107–115.)
=Liegel, Hermann.= Ueber den Ausstülpungsapparat von Malachius und
verwandten Formen. Inaug. Diss., Göttingen, pp. 31, 1 Taf. (n. d.,
since 1858 and before 1878.)
=Leydig, F.= Zur Anatomie der Insecten. (Archiv f. Anat. Phys. u.
wiss. Med., 1859, pp. 33–89, 149–183, Taf. 2–4, pp. 35 and 38.)
—— Ueber bombardier Käfer. (Biolog. Centralbl., x, 1890, pp. 395,
396.)
=Claus, C.= Ueber die Seitendrüsen der Larve von _Chrysomela populi_.
(Zeits. f. wissens. Zool., xi, 1861, pp. 309–314, Taf. xxv.)
—— Ueber Schutzwassen der Raupen des Gabelschwanzes. (Würzburger
Naturw. Zeitschrift, 1862, iii, xiv; Sitz. am., 28 Juni, 1862.)
=Rogenhofer, Alois.= Drei Schmetterlingsmetamorphosen. (Verhandlungen
der k. k. zoolog.-bot. Gesellschaft, Wien, xiii, 1862, pp.
1224–1230.)
=Fitch, Asa.= Eighth report on the noxious and other insects of ...
New York. (Trans. N. Y. State Agric. Soc., 1862, xxii, pp. 657–684),
p. 677. (Separate.)
=Guenée, Achille.= D’une organe particulier que présente une chenille
de Lycæna. (Annales Soc. Ent. de France, Sér. 4, 1867, pp. 665–668,
Pl. 13.)
=Landois, L.= Anatomie der Bettwanze, _Cimex lectularius_, mit
berücksichtigung verwandter Hemipterengeschlechter. (Zeitsch. f.
wissens. Zool., 1868, xvii, pp. 206–224, 218–223, Taf. 11, 12.)
=Studer, Theodor.= Mittheilungen der naturforsch. Gesellschaft in
Bern, 1872–1873, No. 792–811, p. 101.
=Candèze, E.= Les moyens d’attaque et de défense chez les insectes.
(Bull. Acad. royale de Belgique, 2 Sér., xxxviii, 1874, pp.
787–816.)
=Mayer, Paul.= Anatomie von _Pyrrhocoris apterus_. (Reichert und du
Bois-Reymond’s Archiv f. Anat. Phys., etc., 1874, pp. 313–347, 3
Taf.)
=Scudder, Samuel Hubbard.= Odoriferous glands in Phasmidæ. (Psyche, i,
pp. 137–140, Jan. 14, 1876; Amer. Nat., x, p. 256, April, 1876.)
—— Prothoracic tubercles in butterfly caterpillars. (Psyche, i, pp.
64, 168, 1876.)
—— Organs found near the anus of the ♀ pupa of Danais, which recall
the odoriferous organs mentioned by Burnett, transl. Siebold’s Comp.
Anat. as occurring in Argynnis and other genera. (Psyche, iii, p.
278, 1882, p. 453, note 22.)
—— Glands and extensile organs of larvæ of blue butterflies. (Proc.
Bos. Soc. Nat. Hist., xxxiii, pp. 357, 358, 1888.)
—— Butterflies of Eastern United States. i-iii, 1889.
—— New light on the formation of the abdominal pouch in Parnassius.
(Trans. Ent. Soc. London for 1892, January, 1893, pp. 249–253.)