Entomology : with special reference to its biological and economic aspects . y reservoirs (Fig. 153) may bepresent, and the glands are frequentlybranched or lobed, and, though usuallyconfined to the head, may extend into thethorax or even into the abdomen. Many insects have more than one pairof glands opening into the pharynx orcesophagus; thus the honey bee has sixpairs and Hymenoptera as a whole haveas many as ten different pairs. Thoughall these are loosely spoken of as salivaryglands, it is better to restrict that term tothe pair of glands that open at the hypo-pharynx. All these cephalic
Entomology : with special reference to its biological and economic aspects . y reservoirs (Fig. 153) may bepresent, and the glands are frequentlybranched or lobed, and, though usuallyconfined to the head, may extend into thethorax or even into the abdomen. Many insects have more than one pairof glands opening into the pharynx orcesophagus; thus the honey bee has sixpairs and Hymenoptera as a whole haveas many as ten different pairs. Thoughall these are loosely spoken of as salivaryglands, it is better to restrict that term tothe pair of glands that open at the hypo-pharynx. All these cephalic glands are evagina-tions of the stomod?eum (ectodermal inorigin) and consist of an epithelial layerwith the customary intima and basementmembrane (Fig. 154). The nuclei arelarge, as is usually the case in glandularcells, and the cytoplasm consists of a denseframework (appearing in sections as anetwork) enclosing vacuoles of a clearsubstance—the secretion; the chitinousFig. 153. A simple salivarygland of Ccccilius. c,canal; d, duct; g, g, gland-ular cells.—After Right salivary gland of cockroach, ventral aspect, c, common duct; g, gland; h,hypopharynx; r, reservoir.—After Miall and Denny. ANATOMY AND PHYSIOLOGY 123
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectentomology, bookyear1
