128 INTERNAL ANATOMY OF INSECTS. 
'Treviranus calls it a saliva-vessel*—since in the Mygale 
avicularia and other spiders, the effect of the bite is said 
to be so venomous as to occasion considerable inflamma- 
tion, and sometimes death”. ; 
v. Scent-secretors (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 Julzd@, at least Julus and Porcellio*, cover 
themselves, when alarmed, with a flud of this kind, or emit 
one, for this faculty is not peculiar tothe species noticed by 
Savi. I observed early in the year, when I handled Julus 
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 spiracies as has been supposed: each of these 
orifices, as we learn from Savi, terminates internally in 
a black vesicle, which is the reservoir of the fluid’. The 
most remarkable insect for its powers of annoyance in 
this way, is one on that account called the bombardier 
* Arachmd.-31. ¢t. nf 21. p. 9. b ON. Dict. d@’ Hist, Nat. xxii, 
14 comp:, Wor, Ieps 127, © N, Dict. @ Hist. xxviii, 4, 
* Osservazioni, &e. 18—, 
