122 ENTOMOLOGY 
two salivary ducts into a common, or evacuating, duct; a pair 
of salivary reservoirs (Fig. 153) may be 
present, and the glands are frequently 
branched or lobed, and, though usually 
confined to the head, may extend into the 
thorax or even into the abdomen. 
Many insects have more than one pair 
of glands opening into the pharynx or 
cesophagus; thus the honey bee has six 
pairs and Hymenoptera as a whole have 
as many as ten different pairs. Though 
all these are loosely spoken of as salivary 
glands, it 1s better to restrict that term to 
the pair of glands that open at the hypo- 
pharynx. 
All these cephalic glands are evagina- 
tions of the stomodeum (ectodermal in 
origin) and consist of an epithelial layer 
with the customary intima and basement 
membrane (Fig. 154). The nuclei are 
large, as is usually the case in glandular 
cells, and the cytoplasm consists of a dense 
A simple salivary : ; : ; 
gland of Cacilius. c, {Yamework (appearing in sections as a 
canal; d, duct; g,g, gland- network) enclosing vacuoles of a clear 
ular cells.—After Kose. $ . . 
substance—the secretion; the chitinous 
Big. 153: 
Right salivary gland of cockroach, ventral aspect. c, common duct; g, gland; h, 
After Miatyt and DENNY. 
hypopharynx; r, reservoir. 
