Guide to the study of insects, and a treatise on those injurious and beneficial to crops: for the use of colleges, farm-schools, and agriculturists . ia are very large and close together,the commissures, or connecting filaments being very short, andsmall in proportion. ORGANS OF NUTRITION. These consist of the alimentary canaland its appendages, or accessory glands (Fig. 44). We havealready treated of the external appendages (mouth-parts)which prepare the food for digestion. The simplest form ofthe alimentary canal is that of a straight tube. In the larvaof titylops and the sedentary young of
Guide to the study of insects, and a treatise on those injurious and beneficial to crops: for the use of colleges, farm-schools, and agriculturists . ia are very large and close together,the commissures, or connecting filaments being very short, andsmall in proportion. ORGANS OF NUTRITION. These consist of the alimentary canaland its appendages, or accessory glands (Fig. 44). We havealready treated of the external appendages (mouth-parts)which prepare the food for digestion. The simplest form ofthe alimentary canal is that of a straight tube. In the larvaof titylops and the sedentary young of Bees, it ends in a blindsac, as they live on liquid food and expel no solid well developed, as in the adult insect, it becomes a long-convoluted thick muscular tube, subdivided into different partswhich perform different functions and have distinct names,taken from analogous organs in the vertebrate animals. Thisdigestive tube is composed of three coats, the outer, or peri- ORGANS OF NUTRITION. 35 toneal; the middle, or muscular; and the inner, or mucous. Themucous coat is variously modified, being plaited or folded ; or, h f k. in as in the Orthoptera and carnivorous Coleoptera, it is solidifiedand covered with rows of strong horny teeth, forming a sort ofgizzard. The alimentary canal is held in place by retractormuscles, but principally by exceedingly numerous branches ofthe main tracheae. This canal (Fig. 45) is subdivided into the mouth and plia-i; the oesophagus, supplementary to which is the crop, or sucking stomach of Diptera, Lepidoptera, and Hymenoptera ;theproventriculus, or gizzard ; theventriculus, or true stomach,and the intestine, which consists of the ilcum, or short intes- FK;. 44. Anatomy of Sphinx ligustri. in, i, q, the nervous cord resting onthe floor of the body; at e, the ganglia form a brain-like organ, much larger thanthe ganglia of the thorax (m) and abdomen ( which, when at rest, is rolled np between thelabial palpi (b). From
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Keywords: ., bookcentury1800, bookdecade1870, bookpublishe, booksubjectinsects
