BIRDS 



163 



The Internal Organs, or Viscera (Figs. 304 and 305). 

 — The viscera (vis'se-ra), as in most vertebrates, include 

 the food tube and its glands ; the lungs, the heart, and 

 larger blood vessels; the kidneys and bladder and the 

 reproductive organs. The lower part, or gullet, is en- 

 larged into a crop. It is largest in grain-eating birds. It 



Fig. 304. — Anatomy of Dove x%. 



bk, keel of breastbone; G, g, brain; Ir, 

 windpipe; hi, lung; A, heart; sr, gul- 

 let; k, crop; dr, glandular stomach; 

 mm, gizzard; d, intestine; n, kidney; 

 ///, ureter; eil, openings of ureter and 

 egg duct into cloaca, kl. 



Fig. 305. — Food Tube of Bird. 



P, pancreas; C, caeca. 

 Question: Identify each part by means 

 of Fig. 304. 



is found in the V-shaped depression at the angle of the 

 wishbone, just before the food tube enters the thorax. 

 The food is stored and softened in the crop. From the 

 crop the food passes at intervals into the glandular stomach. 

 Close to this is the muscular stomach, or gizzard. Are the 

 places of entrance and exit on opposite sides of the gizzard, 

 or near together ? (Fig. 304.) Is the lining of the gizzard 



