138 INTERNAL ANATOMY OF INSECTS. 



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 5 , 

 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 (zotteri) 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 larvae fix themselves previously to their be- 

 coming pupae S 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 l . Some- 



a VOL. II. p. 244. b Ramdohr Anat. t. ii. vi. 



c Ibid. 20. See above, p. 107. As some of the Sialistcria 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. 



e Reaum. vi. Pref. xxviii. 177. { Ibid. 253. 



* Ibid. iii. 375. h Anat. t. xii./. 6. ' Ibid. xxi./. 3. / /. 



