The dyeing of textile fabrics . ^ regular intervals of four to six days. Onor about the thirtieth day the animal ceases to take food,and evinces a restless activity. At this period it is placedon birch twigs, tfcc, where it soon begins to spin-. Fig. 12.—Silkworm on Mulberry Leaf. Chap. SILK GLANDS OF THE SILKWORM. 45 The silk substance is secreted by two glands symmetri-cally situated on each side of the body of the caterpillar,below the intestinal canal. Each gland, as shown inFig. 13, consists of three parts : a narrow tube IC withnumerous convolutions, the veritable secreting portion
The dyeing of textile fabrics . ^ regular intervals of four to six days. Onor about the thirtieth day the animal ceases to take food,and evinces a restless activity. At this period it is placedon birch twigs, tfcc, where it soon begins to spin-. Fig. 12.—Silkworm on Mulberry Leaf. Chap. SILK GLANDS OF THE SILKWORM. 45 The silk substance is secreted by two glands symmetri-cally situated on each side of the body of the caterpillar,below the intestinal canal. Each gland, as shown inFig. 13, consists of three parts : a narrow tube IC withnumerous convolutions, the veritable secreting portion ;a central part (c b) somewhat expanded, and constitutingthe reservoir of thesilk substance; acapillary tube B A,connecting the re-servoir with a simi-lar capillary canalat A, common toboth glands, andsituated in the headof the animal,whence issues thesilk. The silk sub-stance as containedin the central re-servoir is a clear,colourless, gelatin-ous liquid. Accord-ing to Duseigneur,this is surroundedby a layer of anothersubstance, colour-less when the silk is white, coloured when it is yellow,and which possibly constitutes the silk-gum to bealluded to subsequently. The whole is enclosed in a thinmembrane. A transverse section (Fig. 14)
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectdyesanddyeing, bookye
