Viscera of Birds. 



59 



a glandular stomach (c) communicating with the 

 gizzard, or true muscular stomach (c). This cavity 

 has a thick muscular wall consisting chiefly of two 

 masses of muscle united by a strong tendon, and 

 lined by a rough horny cuticle ; into this birds fre- 

 quently introduce small stones which assist in tri- 

 turating or grinding the food, as this organ is chiefly 

 the place where the material of the food is reduced 



FIG. 24. 



b, crop : i; c, glandular stomach and gizzard. 



mechanically to a condition of pulp to prepare it for 

 further digestive changes. The gastric juice secreted in 

 the glandular stomach is here thoroughly mixed up 

 with it, and the food mass is thus prepared for the 

 intestinal canal. The gizzard is especially strong in 

 grain, or fruit-eaters, weak or absent in flesh-eaters. 



Birds have two separate ventricles in the strong 

 muscular heart ; one on the right side for propelling 



