134- INTERNAL ANATOMY OF INSECTS. 



Treviranus calls it a saliva- vessel a since in the My gale 

 avicularia and other spiders, the effect of the bite is said 

 to be so venomous as to occasion considerable inflamma- 

 tion, and sometimes death b . 



v. Scent-seer etor s (Osmateria). Amongst other means 

 with which insects are gifted for the annoyance of their 

 foes and pursuers, are the powerful scents which many of 

 them emit when alarmed and in danger. Concerning 

 the internal organs by which these effluvia are secreted 

 we possess but little information, but more notice has 

 been taken of the external ones by which they are emit- 

 ted. We may conclude in general, that the secretory 

 organs are membranous sacs or vesicles, perhaps termi- 

 nating in longer or shorter blind filiform vessels, some- 

 times secreting a fetid fluid, and at others a fetid gaseous 

 effluvium. The lulicUe, at least lulus and Porccllio c , cover 

 themselves when alarmed, with a fluid of this kind, or 

 emit one, for this faculty is not peculiar to the species 

 noticed by Savi. I observed early in the year, when I 

 handled lulus terrestris, that it was covered with a slimy 

 secretion, of a powerful scent, which stained my fingers 

 of an orange colour. The spiraculiform pores that mark 

 the sides of the animal are the outlets by which this fluid 

 is emitted, and not spiracles as has been supposed : each 

 of these orifices, as we learn from Savi, terminates in- 

 ternally in a black vesicle, which is the reservoir of the 

 fluid d . The most remarkable insect for its powers of 

 annoyance in this way, is one on that account called the 

 bombardier (Brachinus crept fans), which can fire nume- 



Arachnid. 31. /. ii./. 21. p. 9. h N. Diet. d'Hist. Nat. xxii. 

 114. 117. comp. VOL. I. p. 127. e Rid. xxviii. 6. 



d Osservazioni, &c, 13 , 



