Entomology for beginners; for the use of young folks, fruitgrowers, farmers, and gardeners; . FIG. 35. — Profile view of embryoHoney-bee, lettering as in Fig , nervous cord; uG, brain; D,digestive canal; sch, the oesophagus;St, stigmatal openings of the tra-cheal system; R, heart.—After Bliit-schli. ,-am Of-. FIG. 36.—Embryo of the Louse, am,serous membrane; db, amnion; as,antennas; rfc, forehead.—After Mel-nikow. insect hatches the last steps in the elaboration of the larvalform are taken. As to the development of the internal organs, the nervoussystem first originates; the alimen
Entomology for beginners; for the use of young folks, fruitgrowers, farmers, and gardeners; . FIG. 35. — Profile view of embryoHoney-bee, lettering as in Fig , nervous cord; uG, brain; D,digestive canal; sch, the oesophagus;St, stigmatal openings of the tra-cheal system; R, heart.—After Bliit-schli. ,-am Of-. FIG. 36.—Embryo of the Louse, am,serous membrane; db, amnion; as,antennas; rfc, forehead.—After Mel-nikow. insect hatches the last steps in the elaboration of the larvalform are taken. As to the development of the internal organs, the nervoussystem first originates; the alimentary canal is next formed;and at about this time the stigmata and air-tubes arise as 38 ENTOMOLOGY, invaginations of the outer germ-layer. The development ofthe salivary glands precedes that of the urinary tubes; which,with the genital glands, are originally offshoots of theprimitive digestive tract. Finally the heart is formed. When the insect hatches, it either cuts its way throughthe egg-shell by a temporary egg-cutter, as in the flea; orthe expansion of the head and thorax and the convulsivemovements of the body, as in the grasshopper, burst theshell asunder. The serous membrane is left in the shell,but in the case of grasshoppers the larva on hatching isstill enveloped in the amnion. This is soon cast as
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Keywords: ., bookcentury1800, bookdecade1880, bookpublishe, booksubjectinsects
