DIGESTIVE SYSTEM 395 



side of the proventriculus is a small red body, the 

 spleen. 



3. The gizzard is a large hard body, somewhat flattened 



laterally, and with very thick muscular walls, the 

 muscular fibres radiating outwards from a bluish 

 tendon in the centre of each lateral surface. It 

 forms a powerful mill for grinding up the food. 



The proventriculus opens into the gizzard at its 

 dorsal border, and rather to the left side ; while the 

 duodenum leaves it close to the same spot, but more 

 to the right side. 



Split open the gizzard along its ventral edge, and wash 

 out the contents. Note the following points : — 



a. The great thickness of the muscular walls. 



b. The thick horny epidermis which lines the cavity of 



the gizzard, and in which small stones are usually 

 found imbedded. 

 C. The openings of the proventriculus and duodenum, 

 placed side by side at the dorsal edge. 



4. The duodenum is a. U-shaped loop, formed by the first 



part of the intestine. The pancreas lies between the 

 two limbs of the loop, the further dissection of which 



Fig. 48. — Columba livia. Dissection of the male from the right side. 

 Half the liver and the greater part of the intestine have been 

 removed. In the right wing, the bones and the arrangement of the 

 primary and secondary feathers are shown. The reproductive 

 organs are omitted, (a. m. m.) 



A. , nostril. AD, ad-digital primary feather. B, external auditory meatus, 

 B"W",,bastaxd wing. C, oesophaglis. CA, right carotid artery, D, crop. 

 DA, aorta., E, keel of the sternum, F, right auricle. Q-, right ven- 

 tricle. ■ B.V', hepatic vein. H 1, left bile-duct. H 2, right bile-duct. 

 I, distal' end of stomach. I A, right innominate artery. IV, posterior vena 

 cava. ,JA, left innominate artery. JV, right jugular vein, K, gizzard, 

 L, liver. M, proximal limb of duodenum. MD, the two mid-digital primary 

 feathers. MP, the six metacarpal primary feathers. M 1, first metacarpal. 

 M2, secpnd metacarpal. M3, third metacarpal. IM", cloacal aperture. 

 N 1, first digit of manus, O, bursa IFabricii. 1, proximal phalanx of second 

 digit of manus. O 2, distal phalanx of second digit of manus. P, pancreas. 

 PA, right pectoral artery. PD, pre-digital primary feather. PV, portal 

 vein. ;'P 1, first pancreatic duct. P 2, second pancreatic duct. P 3, third 

 pancreatic duct. Q, pygostyle. B, rectum. BC radial carpal bone. 

 BX, reotrioes, or tail-feathers. B 1, third digit of manus. S, ureter. 

 SA, right subclavian artery. SV, right anterior vena cava. T, rectal 

 diverticulum. U, kidney. UO, ulnar carpal bone. V, pelvis. 'W, lung. 

 X,' humerus, y, radius. Z, ulna. 



