336 



TEXT-BOOK OF ENTOMOLOGY 



by the epithelial cells passes into the salivary duct. The glands 

 are externally bathed by the blood. 



In many insects, including lepidopterous larvae, the single median 

 opening of the salivary duct is converted into a spraying apparatus. 



In the adult Lepidoptera, according to Kirbach : 



B 



FIG. 329. Salivary glands of the honey-bee : systems No. 1-3. x 15: r, salivary valve (of 

 systems 2 and 3) at base of tongue ; Ip, labial palpus ; nix, maxilla ; *. salivary opening of system 

 1 in hypopharyngeal plate ; no, openings in plate for termination of taste-nerve ; ', oesophagus ; 

 gd, salivary duct ; b, junction of ducts of system No. 2 ; c, junction of ducts of system No. 3 ; 

 c, go, salivary sacs ; j#, front lobe ; bl. back lobe ; a, chitinous duct, with spiral thread. />. .-inj_ r k> 

 acinus of system No. 1, x 70 : it, nucleus ; <, salivary track ; d, large duct. C, single pouch, or 

 acinus, from system No. 2: a propria or outer membrane; so, secreting cells. /'. termination of 

 system No. 3 :\, 2 , 3 , 4, lines marking end of section.; d, duct in section ; sc, secreting cells in sec- 

 tion ; n, nucleus. After Cheshire. 



" Its lower half forms a thick chitinous gutter, with a concave cover above, 

 in which the similarly shaped upper half lies encased, so that between the 

 two only a small semicircular opening remains. Powerful muscles extend from 

 the cover to the lower side and to the two ridges of the bottom plate ; through 

 their contraction the upper channel is elevated, and presses out of the hinder 

 part of the ducts into the space thus formed a great quantity of the saliva, 

 which by allowing the contraction of the cover-muscle through the crevice- 

 like opening, which is situated in the lower edge of the mouth-opening, becomes 



