. Elementary text-book of zoology, general part and special part: protozoa to insecta. Animals. NT) repeated mechanical action (masticatory stomach of Cray-fish) or by the secretion of digestive fluids (pepsin) furthers digestion; or it may, as in birds, subserve both these functions. From the stomach the food passes into the mid-gut. Dilatations and out-growths of the buccal cavity give rise to cheek and throat pouches, of the oeosphagus to the crop, of the stomach to blind sacs which serve as reservoirs for the food (stomach of Ruminants) (figs. 47 & 48). In the middle section of the ali
. Elementary text-book of zoology, general part and special part: protozoa to insecta. Animals. NT) repeated mechanical action (masticatory stomach of Cray-fish) or by the secretion of digestive fluids (pepsin) furthers digestion; or it may, as in birds, subserve both these functions. From the stomach the food passes into the mid-gut. Dilatations and out-growths of the buccal cavity give rise to cheek and throat pouches, of the oeosphagus to the crop, of the stomach to blind sacs which serve as reservoirs for the food (stomach of Ruminants) (figs. 47 & 48). In the middle section of the alimentary ca- nal,or intestine, the digestive processes, al- ready c o m - menced in the mouth by the action of the salivary secre- tion and con- tinued in the stomach by the action of the pepsin of the gastric juice (upon albumins in an acid solution), is completed. The food constituents which have been so far unacted upon (chyme) are in the intestine submitted to the action of the secretions of the liver, pancreas, and intestinal glands, and by them converted into the chyle, which is absorbed by the intestinal walls; the albumins being converted, as in the stomach, into soluble Fig. 49.—Alimentary oanai of modifications by the action of ti-ypsin lt^XlZt7t^Z'. (^-^ting, however, only in alkaline solutions). Oe, oesophagus; s, suckinrj The intestine often attains a great length, t?breS:...?ect^!''''''" and becomes divided into regions_ possessing a difierent structure; , in the intestine of mammals three regions can be distinguished—duodenum, jejunum, and ileum. Its surface is, as a rule, increased by the develop- ment of folds and villi, and sometimes of outgrowths. Amongst Fig. 47.—Alimentary canal and ac- cessory glands of a caterpillar. O, mouth; Oe, oesophagus ; Sp D, salivary glands; Se, spinning glands ; MD, intestine (mid-gut); AT), rectum (hind gut); M(J, Mal- pighian Please note that these images are extracted from scanned page images that may hav
Size: 1323px × 1888px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectanimals, bookyear1892
