ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
389 
Defensive Glands of Coleoptera.* — L. Bordas, from a series of ob- 
servations, finds that in most Coleoptera there are defensive or anal 
glands formed of the following parts : — (1) a glandular region ; (2) an 
efferent canal ; (3) a vesicular reservoir or receptacle ; and (4) an ex- 
cretory duct. The liquid secreted is expelled by the contraction of the 
muscular wall of the vesicle, but its discharge is assisted by the con- 
traction of certain muscles affixed to the excretory canal, and by the 
upward movement of the extremity of the abdomen. The excretory 
canal and vesicle are lined by the cuticle, and are therefore probably 
ectodermic in origin ; the glands themselves are metameric or appen- 
dicular, homologous with salivary glands, poison glands, and genital 
glands. 
Anal Gland of Dytiscus.f — Fr. Dierckx maintains that this has been 
misinterpreted by Bordas. The anal gland belongs to the unicellular 
type, and secretes an oily substance which facilitates respiration by 
keeping the water out of the air-reservoir under the elytra. The de- 
fensive apparatus is quite different ; it is the rectal pouch which is 
violently emptied when the beetle is irritated. 
Defensive Gland of Erachynus.J — Fr. Dierckx has a short note on 
this subject, showing wherein his results differ from those obtained by 
M. Bordas.§ In Brachynus crepitans the gland is double, consisting at 
either side of secretory lobes, a collecting canal, and a reservoir. The 
two reservoirs open by minute pores on the dorsal surface of the py- 
gidium. The collecting canals have no muscular coat, as asserted by 
Bordas. The secretion is limpid, colourless, and has only a faint odour ; 
the author believes that it contains an unknown active principle whose 
special character is its exceeding volatility. He believes that the liquid 
boils at a temperature of about -f- 9° under a pressure of 760 mm. In 
spite of the colourless nature of the fluid, the discharge stains paper or 
the skin a brown colour. This fact, and the mechanism of discharge, the 
author explains as follows : — When the orifices of the glands are opened, 
the liquid within the reservoir vaporises suddenly ; simultaneously the 
contents of the rectum are voided, and the escaping gas blows the excreta 
into minute particles, which constitute the solid staining portion of the 
discharge. 
Systematic Position of Pulicidse.|| — Herr Fr. Dahl briefly recapitu- 
lates his reasons for thinking that the Pulicidse are nearly related to the 
Diptera and especially to the Phoridse. He believes that Scatopse , Pulex , 
and PJiora have all arisen from a primitive form to which he gives the 
name of Archiscatopse. This form is regarded as having possessed five- 
jointed labial and maxillary palps and a simple hypopharynx. He 
believes further that from the Phora- stem lateral branches arose which 
approximated in character towards Pulex , and that Pulicipliora is an 
example of such transitional forms. 
* Comptes Remius, cxxviii. (1899) pp. 1009-12. f Tom. cit., pp. 1126-7. 
X Zool. Anzeig., xxii. (1899) pp. 153-7 (4 figs.). 
§ Tom. cit., p. 73. Cf. this Journal, ante, p. 157. 
|| Arch. Naturgeschichte, lxvi. (1899) pp. 71-86 (15 figs.). 
1899 2 d 
