Miscellaneous, IGT 



this against the theory of the migration of the embryo of the 

 Rhizocephala. I also add that all the facts contained in this note 

 are perfectly well explained under the hypothesis of direct fixation 

 which still appears to me much the most probable. — Comptes 

 Rendus, July 5, 1886, p. 84. 



The Bed-Bug and its Odoriferous Ai^paratus. 

 By M. J, KiJNCKEL. 



I have ascertained that the young Oimtces, on issuing from the 

 egg, bear three odorific glands, situated in the dorsal region of the 

 abdomen. These glands occupy the median portion of the first 

 three segments ; all three, of the same dimensions, when seen under 

 the microscope affect the form of a more or less inflated satchel ; 

 their outline exactly reproduces the contour of a melon-glass, with 

 the bottom turned towards the head. Each gland opens externally 

 by two orifices, placed on either side of the median line, and arranged 

 transversely at the margin of the first, second, and third tergites, 

 just over the line of separation of the segments ; they have the 

 aspect of open button-holes. 



If we examine the young bugs when their digestive tube is gorged 

 with blood, it is impossible, on account of their opacity, to perceive 

 the odoriferous glands : to study these we must render the insects 

 transparent by means of special artifices. We shall not at present 

 describe their histological structure, but merely remark that they 

 are cutaneous glands formed by a fold of the skin ; moreover, after 

 treatment with caustic potash we can ascertain that the cuticle of 

 the integument is continuous with the invaginated cuticle which 

 lines the interior of the gland. 



These three ahdominal find dorsal glands persist until the last 

 change of skin ; they then become atrophied and are replaced by a 

 ilioradc and sternal glandular ajiparatus. The Cimicides, which 

 drink blood, like the Scutclleridcs, Pentatomides, Coreides, Lygseides, 

 &c., which suck sap, are therefore provided with two systems of organs 

 of secretion, situated in two opposite regions of the body, according 

 as they are in the state of larva or pupa, or in the adult state. 



The presence at different ages in the same insect of glands having 

 different anatomical relations, but possessing the same physiological 

 attributes, is a fact which leads us to interesting deductions. In 

 fact when I first indicated it, in 1866*, I endeavoured to explain 

 it, and I said that the glands of the pupa3 became atrophied, because 

 in the Pentatomides and others the scutellum, elytra, and wings 

 coming to cover the su])erior arches of the abdomen, would place an 

 obstacle in the way of the performance of their physiological func- 

 tion ; but the bed-bug having onl)'^ a short scutellum, small elytra, 

 and no wings, the tergites of the abdomen are never covered, and it 

 would seem that my explanation was defective : it will suffice for 

 me to remark that this Hemipteron is an aberrant type, transformed 

 by adaptation, that is to say, having lost its aerial locomotor oi'gans 

 to conform to a sedentary existence subordinated to the biological 

 conditions imposed by its cohabitation with man ; on the other hand, 



* ' Comptes Rendus,' 2'' semestre, 18GG, p. 483. 



