444 



THE INSECTA. 



§ 347. 



Coleoptera, these anal glands secrete a caustic fluid which has a penetrating 

 and more or less aromatic odor. They are somewhat ramified, or composed 

 of vesicles disposed botryoidallj, and open into one or several long, excre- 

 tory ducts.'" These last open into two pyriform, muscular reservoirs, whose 

 powerful contractions expel, as a means of defence, the secreted fluid.'"' The 

 Formicidae, also, have, in the anal region, a glandular apparatus from 

 which they eject a caustic, acid fluid. This apparatus is single and com- 

 posed of one reservoir whose neck opens into a simple tube."'' The larvae 

 of Harpyia, also, defend themselves by ejecting an irritating liquid secreted 

 by a glandular sac, which opens directly back of the head on the under 

 surface of the first segment of the body. 



Among the Ilymenoptera, the females of the Vespidae, Fossores, An- 

 drenidae, and Apidao, have, in the anal region, a glandularapparatus which 

 secretes a poisonous fluid introduced by means of a hollow sting into the 

 tissues of their prey or enemies.''" This Poison-apparatus is composed of 

 two long tubes which are sometimes very ramose. ''■'' The intimate struc- 

 ture of these tubes resembles that of the salivary glands.'^'" The two 

 poison-glands are sometimes isolated, sometimes united into a common 

 canal, and their product is poured into a pyriform reservoir, which has 

 thin but contractile walls, whose longer or shorter excretory duct opens 

 into the sting. '^'' This sting is formed by the intimate union of two lateral 

 pieces, and plays in a cleft horny sheath. Often, its extremity is covered 

 with backwardly-pointing denticles.'^-' Both the sheath and the sting have, 

 at their base, a peculiar muscular apparatus by which they are protruded 

 and withdrawn. 



near the arms, ejaculate a highly stinking liquid. 

 With the Silphidae, where this apparatus is single, 

 the reservoir opens laterally into the rectum ; see H. 

 Meckel, in MiiUer's Arch. 1846, p. 47, and L. Du- 

 four, Ann. d. So. Nat. VIII. 18:26, p. 15, III. PI. X. 

 fig. 3, 4, 5, PI. XIII. flf,'. 5, 7 (Dytiscus, Gijrinus 

 and Silplia). With Gryllotalpa, the anal glands 

 consist of small lobular licjdies inserted on the re- 

 servoir which receives their product: see L. Dii- 

 four, Reclierch. sur les Orthopt, &c., p. 346, PI. 

 II. fiff. 19. 



5 With the Carabidae, and Stai)hylinidae ; see 

 Li. DitfouT, Ann. d. So. Nat. VIJI.'l,S26, p. 6 ; 

 II. PI. XX. X.X;i.; III. PI. X.; and VII. PI. XIX. 

 XX.; J. MiiUer, De Glandul. Struct. &c. Tab. I. 

 fig. 13-18 ; and Stein, Vergl. Anat. u. Pliysiol. d. 

 Insekt. 1847, Taf. I. fis. 4, g. g. {Dianous) and 

 Taf. III. fig. 3, 1. n. (Oxi/telus). 



*< With Brachinus, as is well known, this prod- 

 uct is so volatile as to immediately become gase- 

 ous on its ejection.- 



7 See L. Diifour, Rechcrch. sur les Orthopt. &c. 

 p. 413, PI. Vli. fig. 80. 



8 The Bees, which have a poison-apparatus of 

 this kind, ought to be regarded as females whose 

 genital organs are undeveloped. Many fossorial 

 Hymenoptera, which feed theii- young with insects, 



wound these last with their sting, that they may be 

 mastered, and conveyed the more easily to the 

 nest. Indeed, some carry their prey into their 

 nests transfi.xed with the sting. (See my Observ. 

 quaed. de O.vybelo atque Miltogramma, 1841, p. 

 11.) The wound does not always kill the insect, 

 but simply disables it, so that they remain fresh 

 for several days by the side of the larvae for whose 

 food they are to serve. 



'■< Tliere are two simple tubes with Vespa, Scolia, 

 Crabro, Halictus, Apis, &c. ; but they are ram- 

 itted with Pompilus, P/iilant/ms, Larra, Bom- 

 bus, &c. 



10 For the intimate structure of these poison- 

 glands, see H. Meckel, in JUu//er'.s Arch. 1846, p. 

 45, Taf. III. 



11 This poison-apparatus is described more in 

 detail in the works of S wamincrdamm , Bib. der 

 Nat. p. 183, Taf. VIII. (Jpis) ; Brandt and 

 Rntzeburs, Mediz. Zool. II. p. 203, Taf. .\.\V. fig. 

 39-42 ; Ramdolir, Abhandl. lib. d. Verdauungs- 

 werkz. &o. Taf. XIV. fig. 5 (Pompilus), and 

 Suckow, in Heusins^er^s Ztitsoh. II. Taf. XIV. 

 fig. 38, 46 (A/iis and Crabro).\ 



1-' See Swammerdamm, loo. cit. Taf. XVIU. fig. 

 3. 



* [ § 347, note 6.] For ihe peculiar glandular 

 apparatus for this purpose, with Brachinus, see 

 Karsten, in MuUer's Arch. 1848, p. 367. Con- 

 trary to other Zootomists, this observer regards 

 this apparatus as of a urinary nature, for he states 

 that an analysis of its secretion furnishes a product 

 analogous to urea. — Ed. 



t [ § 347, note 11.] The poison of the poison 

 apparatus in the Hymenoptera has been investi- 

 gated by fFill (SclUeiden and Froriep's Not. 

 1848, Sept. p. 17) who found, with Ants, Bees, and 

 Wasps, that this product consisted of formic acid 

 and a whitish, fatty, sharp residuum, the former 

 being the poisonous substance. — Ed. 



