138 INTERNAL ANATOMY OF INSLCTS. 
sion I observed to you that many predaceous, carnivo- 
rous, 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 b , 
who, had there been such an organ, would doubtless 
have discovered it : but as the stomach of all of them 
is distinguished by those minute cceca or blind vessels, 
which he denominates shags (zotten) c , perhaps these 
may be the secretors of this fluid, probably analogous 
to the gastric juice d ; in which case its primary office 
would be the digestion of the food. We are not how- 
ever warranted in considering every fluid effused from 
the mouth as saliva. The glutinous material with which 
wasps cement the woody fibres for their paper edifices e ; 
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 f ; and that with which the aphi- 
divorous lame fix themselves previously to their be- 
coming pupae e , — may be a secretion distinct from sa- 
liva ; possibly intermediate between it and gum or the 
matter of silk, and secreted by peculiar organs. In the 
wasp, however, Ramdohr discovered nothing of the 
kind h ; and in Syrphus, as before observed, the saliva- 
secretors are very peculiar in their structure, as if ap- 
propriated to the secretion of a peculiar fluid '. Some- 
a Vol. II. p. 244 — . b Ramdohr Anat. t. ii.— vi. 
c Ibid. 20. See above, p. 107. As some of the Sialisteria render 
to the stomach (see above, p. 131), there seems no small affinity be- 
tween these shags and those organs. 
d Cuv. Anat. Comp. iv. 132, 136. 
c Reaum. vi. Pref. xxviii. 177—. f Ibid. 253—. 
g Ibid. iii. 375. '' Anat. t. xii./. 6. ' Ibid. xxi./. 3. / /. 
