INTERNAL ANATOMY OF INSECTS. 131 
pathi, Chrysopa Perla, and lulus tcrrestris. The most 
usual number of the saliva-secretors is tivo a ; but some- 
times, as in the first of the last-named insects, there is 
only one b ; in others [Pentatoma Baccarum) there are 
three, the exterior one consisting of a pair of reservoirs 
connecting'with the gullet by a single capillary tube c ; in 
Pentatoma prasina there appear to be four d ; in Nepa 
cinerea, even six — the exterior double pair in this insect, 
under a powerful lens, is found to consist of spherical 
vesicles, resembling somewhat a bunch of currants'; and 
in Sgrphus arcuatus they are covered with four rows of 
similar ones f . In the flea they consist of two pair of 
spherical reservoirs, each of which is connected with a 
short tube, which uniting with that of the other forms a 
common capillary one connecting with the mouth or 
gullet s ; these organs sometimes terminate below in 
slender vessels; — thus, in Nepa, the inner pair terminates 
in a single vessel of this description h , and in Tabanus and 
Hemerobius apparently in many '. It admits of a doubt 
however, as was lately observed, whether in the Hemi- 
ptera, which have usually more than apairof these organs, 
some are not rather food-reservoirs as in the Diptera. 
The saliva-secretors open either into the instruments 
of suction themselves ( Tabanus, Mused) ; or into the en- 
trance of the gullet (Pentatoma, &c.) ; or, lastly, into that 
of the stomach (Sgrphus, Bombylius). Those which lie at 
the entrance of the stomach consist only of a blind uni- 
3 Ramdohr Anat. t. xviii./. 1. M.f. 5. F. •> Ibid. t. x.f. 1. m. 
c Ibid. t. xxii./. 3. M L. Ramdohr regards the double one as a 
pair; but as they terminate in a single tube, they ought to be reckoned 
as one. * Ibid./. 4. c Ibid./. 2. K, L, M t N. t. xxiii./. 6. 
« Ibid. 177. t. xxi./. 3. 7^. F. e jud.f. 2. G, H. 
'' Ibid. t. xxii./. 2. L. ' Ibid. t. xxi./. 1.0./. xvii./. 0. n. 
K 2 
