132 INTERNAL ANATOMY OF INSECTS 
and some herbivorous beetles, when alarmed emit a drop 
of coloured acrid fluid from the mouth?. That this is not 
secreted in any of the ordinary salival vessels is evident 
from Ramdohr’s dissections of those beetles®, who, had 
there been such an organ, would doubtless have disco- 
vered it: but as the stomach of all of them is distinguished 
by those minute c@ca or blind-vessels, which he denomi- 
nates shags (zotten)°, perhaps these may be the secretors 
of this fluid, probably analogous to the gastric juice‘; in 
which case its primary office would be the digestion of 
the food. We are not however warranted in consider- 
ing every fluid effused from the mouth as saliva. The 
glutinous material with which wasps cement the woody 
fibres for their paper edifices®; that with which some 
sand-wasps moisten the sand which they scrape away, 
of which they form the singular tubes that lead to their 
nests*; and that with which the aphidivorous larvae fix 
themselves previously to their becoming pupee £,—may be 
a secretion distinct from saliva; possibly intermediate be- 
tween it and gum or the matter of silk, and secreted by 
peculiar organs. In the wasp, however, Ramdohr dis- 
covered nothing of the kind*; and in Syrphus, as before 
observed, the saliva-secretors are very peculiar in their 
structure, as if appropriated to the secretion of a peculiar 
fluid‘, Something similar has been observed by Reau- 
* Vor. IL. p. 247—. » Ramdohr Anat, t. ii.—vi. 
* Ibid. 20. See above, p. 101. As some of the Sialisteria render 
to the stomach (see above, p. 125), there seems no small affinity be- 
tween these shags and those organs. i 
4 Cuv. Anat. Comp. iv. 132, 136. 
* Reanm, vi. Pref. xxviti. 177—. Pbide25g=—. 
& Thid, i. 375 » Anat. t. xii. f. 6. i Ibid. xxi. f. 8. 11 
