Page:Insects - Their Ways and Means of Living.djvu/345

 CATERPILI.AR AND THE MOTH

The fresh silk is a liquid formed in two long, tubular glands extending far back from the head into the body of the caterpillar (Fig. 154, 8kGl). The middle part of each tube is enlarged to serve as a reservoir where the silk liquid may accumulate (Fig. 55 A, Res); the anterior narrowed part constitutes the duct (Da), and the ducts

FIG. I. The silk glands and spinning organs of the tent caterpillar A, the silk-forming organs, consisting of a pair of tubular glands (GI, GI), each enlarging into a reservoir (Res), and opening through a long duct (Dct) into the silk press (Pr), with a pair of accessory glands (glands of Filippi, GIF) opening into the ducts B, side view of the hypopharynx (Hphy) with terminal parts of right maxilla (Mx) and labium (Lb) attached, showing the silk press (Pr), its muscles, and the ducts (Dot) opening into it, and the spinneret (,çpt) through which the silk is discharged from the press C, upper view of the silk press (Pr), showing the four sets of muscles (Mcls) inserted on its walls and on the rod-like raphe (Rph) in its roof D, side view of the silk press, spinneret, raphe, and muscles E, cross-section of the silk press, showing its cavity, or lumen (Lum), which is expanded by the contraction of the muscles

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INSECTS