THE SALIVARY GLANDS 



333 



these so-called " salivary glands" in lepidopterous larvae are different 

 structures. They are probably modified coxal glands, belonging to 



the mandibular segment. 



The polygonal epithelial cells of these glands contain branched nuclei, recall- 

 ing those of the spinning-glands. In those caterpillars which feed on leaves, the 

 salivary glands are slightly developed, but in such as 

 bore .into and eat wood, as the Cossidse, the glands are, 

 as figured by Lyonet, very large, forming two sausage- ( 

 shaped bodies passing back to the beginning of the mid- 

 intestine, each ending in a long convoluted filament. 

 The salivary glands of the imago are very long and con- 

 voluted (Fig. 310, sd). 



In the PanorpidiB these glands differ in the sexes, the 

 males having three pairs of very long tortuous tubes, 

 while, in the females, they are reduced to two indistinct 

 vesicles. (Siebold.) 



In the Diptera in general there are two pairs, 

 one situated in the beak, the other in the thorax. 

 In the larvee there is a single pair (Fig. 341). 

 Kraepelin describes a third pair in the Muscidae 

 at the point of transition from the fulcrum to 

 the oesophagus, but Kiuippel has apparently 

 found only what may be fat cells at this point, 

 so that the supposed presence of a third pair in 

 Diptera needs confirmation. In the Psocidae 

 there are two salivary glands, of simple tubular 

 shape (Fig. 325). 



In the Nepidae the salivary glands are four 

 in number, and of conglomerate structure, two 

 being long and extending back into the begin- 

 ning of the abdomen, while the other two are 

 about one-fourth as long. (Figs. 327, 328.) In 

 Cicada, besides a pair of simple tortuous tubes, 

 there is in the head another pair of glands, 

 each composed of two tufts of short lobes, 



situated one behind the other. (Dufour.) In FIO. 325. one of the 

 many Hemiptera (Pyrrhocoris, Capsus, etc.) /"',' 

 there is but a single pair, each gland consisting !,'"'; 

 of four lobes; in the Coccidas each gland is saliv '"' y flufd '-- After Kolbe: 

 divided into two lobes (Fig. 32G) ; in the Aphidae, according to "\Vit- 

 laczil, they consist of two lobes grown together. In the Psyllidae 

 they are said to be absent. 



In Phylloxera vastatrix the saliva is forced through a salivary 



