$ 347. THE INSECTA. 443 
alone, their number is smaller,® and with those of the Lepidoptera, the 
extremities of the six tubes of this kind are insinuated between the tunics of 
the colon; while, with the imagines they are free.” With the Bupres- 
tidae, the larvae have six, but the imagines only four, of these vessels,“ 
IT. Organs of Peculiar Secretions. 
§ 347. 
A great number of the Insecta, in both their larval and their perfect state, 
have glandular organs which secrete very varied products remarkable for 
their specific properties. , 
Many species have a secretory apparatus analogous to the cutaneous 
glands of the Vertebrata, which have received the name of Glandulae odor- 
aferae. These consist of round follicles situated under the skin, whose 
very short excretory ducts open between the segments of the body, or be- 
tween the articulations of its extremities. Their product emits a powerful 
odor, and, with some species, is evacuated in the form of droplets,” or, 
with others, covers the whole surface of the body, being perceived only by 
itsodor.? The disagreeable odor emitted by the Bugs is due to a fluid 
secreted by a single, yellow, or red pyriform gland, situated in the centre 
of the metathorax, and opening between the posterior legs.© With other 
Insecta, there are analogous secretory organs, concealed in the posterior 
extremity of the abdomen, which copiously emit a fetid, troubled liquid, 
through an orifice situated by the side of theanus. These Anal Glands are 
usually double, and consist of simple follicles whose secretory product 
accumulates in round, or oblong contractile reservoirs.” With many 
darva of various Lamellicornes); and Burmeister, 
Trans. of the Entom. Soc. I. Pl. XXIV. fig. 10 (larva 
of a Calosoma), and his Abhandl. z. Naturges- 
chichte d. Calandra, loc. cit. fig. 3. 
19 The larvae of the Apidae and Vespidae have 
only four uriniferous vessels ; see Swammerdamm, 
Bib. der Nat. Taf. XXIV. fig. 6 (larva of a bee) ; 
Suckow, in Heusinger’s Zeitsch. III. Taf. VI. fig. 
180, and Ramdohr, loc. cit. Taf. XIL. darva of a 
Vespa) ; finally, Rathké, in Miiller’s Aych. 1844, 
p. 36, Taf. II. (larva of a Gryllotalpa). 
2 See Lyonet, Traité, &c., Pl. XID, and 
Suckow, Anat. u. physiol. Untersuch. Taf IT. 
21 See L. Dufour, Ann. d. Sc. Nat. XIV. 1840, 
p. 114. Loew (Entom. Zeit. 1841, p. 37, fig. 3) did 
not, probably, observe these canals in the larva of 
Buprestis mariana ; for, otherwise, he would not 
have regarded as such the two caecal d 
of many Tenthredinidae, emit droplets of fluid from 
the surface of their skin from the least touch. Very 
often the odor of this fluid reminds one of fresh 
poppy-juice. The fluid emitted from the cephalo- 
prothoracic articulation, with Colymbetes and 
Dytiscus, has a very nauseating order. I am un- 
able to decide whether or not the transparent liquid 
which escapes with various Aphididae through two 
tubes on their abdomen, belongs to this same cate~ 
gory of secretions. 
2 Cegtain Phryganidae, Hemerobidae, Crabron- 
idae, Scoliadae, Ichneumonidae, &c., emit specific 
odors without the secretion of their Glandulae 
odoriferae being visible. 
3 See L. Dufour, Recherch. loc. cit. p. 266, Pl. 
XVII. fig. 194. Moreover, the opinion that all the 
Bugs emit a bad odor is incorrect ; for with many, 
as for Syr tes, the Glandulae odori- 
at the upper extremity of the stomach, and which 
the Buprestidae have also in their imago-state (see 
38). 
1 With Euprepia, and Zygaena, a finid of this 
kind, yellowishly transparent, exudes under the 
eollar ; and with many Meloidae, Chrysomelidae, 
and Coccinellidae, it pes from the knee-joints. 
The larvae of these last Coleoptera, as well as those 
* { § 347, note 3.] With Belostoma, the odor- 
iferous glands consist of two pretty long caecal 
tubes si d in the ax, b th the other 
viscera, and extending into the anterior part of the 
tath, 
JSerae exhales a very agreeable odor resembling that 
of a fine bergamot pear.* 
4 These anal glands, which Burmeister (Handb. 
I. p. 157), Grant (Outlines, &c., loc. cit. p. 584) 
and other anatomists have mistaken for urinary 
organs, consist, with the Dytiscidae and Gyrinidae, 
of two simple, long and flexuous caeca, whose re- 
servoirs, having two short excretory ducts situated 
abdomen. They open externally between the 
coxae of the posterior legs. See Leidy, loc. cit. p. 
64. — Ep. . 
