. Useful birds and their protection. Containing brief descriptions of the more common and useful species of Massachusetts, with accounts of their food habits, and a chapter on the means of attracting and protecting birds . y of food. Thefood passes from the gullet or the ci-op tothe proventriculus or glandular portion ofthe stomach. This is where the processof digestion begins. Mixed with salivary,ingluvial, and proventricular secretions, thefood next passes to the gizzard or musculardivision of the stomach, where the food grist is ground fineAmong seed-eating birds the heavy, powc-rful muscle
. Useful birds and their protection. Containing brief descriptions of the more common and useful species of Massachusetts, with accounts of their food habits, and a chapter on the means of attracting and protecting birds . y of food. Thefood passes from the gullet or the ci-op tothe proventriculus or glandular portion ofthe stomach. This is where the processof digestion begins. Mixed with salivary,ingluvial, and proventricular secretions, thefood next passes to the gizzard or musculardivision of the stomach, where the food grist is ground fineAmong seed-eating birds the heavy, powc-rful muscles ofthis portion of the stomach are, with the rough, callousedstomach lining, assisted in their work by sand and gravelAvhich are swallowed. This mineral matter takes thei)laceof teeth in grinding the food. In vegetable-feeding birds the intestine is very lono- andmuch coiled, while the digestive tract is generally shorterand simpler in the flesh-eating and fish-eating species. Allthe processes of digestion are remarkably rapid. The sali-vary glands, the liver and the pancreas afl quicklv pour theircopious secretions into the alimentary canal ; the food ischylified after impregnati(m with the biliary and pancreatic. Pig. 17.— Alimen-tary canal of Blue-bird, reiluced; afterAudubon. «,/), gul-let or oesophagus; c,proventriculus; d,gizzard; e, f, h, in-testine; /, cloaca. 42 USEFUL BIRDS. fluids ; the chyle is drawn off by the lacteals, and the residueis excreted. The viijor, perfection, and rai)idity of theseprocesses in insect-eatino- l)irds are such as might be expectedamong animals of such high temperature, perfect respiration,and rapid circulation. The various dilations of the digestive tract serve well their[)urpose of enabling the bird to consume the large amountof food necessary for its maintenance. Digestion is partic-ularlv rapid in the growing young of most birds, for thc}^re{juire not only food sufficient to sustain life, but an extrasu})plv as well to enable them t
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