60 INTRODUCTION. 



conf?ervatlve in place of a solvent power ; and I have observed 

 the like in the Buzzard, Sparrow-Hawk, and other species. 

 When the crop, stomach, and intermediate space are found 

 filled, the solvent action is first perceived in the proventricular 

 space ; and it is probable that the secretion from its glandules 

 effects the solution of the food in all species, for in those of 

 which the epithelium or inner coat is horny and thick, there 

 can be no effusion from the stomach itself. The mass of flesh, 

 mixed with feathers, hair, and bones, being in the stomach re- 

 duced to a kind of pulp, the nutritious parts pass into the in- 

 testine through the pylorus, which rejects the indigestible sub- 

 stances. These, including the inner coats of gizzards, seeds, 

 and other vegetable substances, are, by the contraction of the 

 muscular fibres, thrust into the oesophagus, and voided in 

 rounded dense pellets, which falconers term castings. In 

 the duodenum the pulpy mass is further diluted by the pan- 

 creatic fluid, assumes a homogeneous appearance, and is of 

 a light red colour. On being mixed with the bile it acquires 

 a greenish tint, and deposits the chyle on the surface of the in- 

 testine, whence it is absorbed. The matter adheres tenaciously 

 to the villosities, so as to be with difficulty washed off, and is 

 found along the whole length of the small intestine. The re- 

 fuse enters the rectum, where it is farther diluted by the urine, 

 and is finally ejected in a semifluid state, of a dull green colour, 

 mixed with flakes of white, being projected to a considerable 

 distance. 



The modifications which the several parts of the digestive 

 organs undergo in the different families of birds are very numer- 

 ous. Thus, the oesophagus is extremely wide in some, and very 

 narrow in others ; the crop is sometimes altogether wanting, 

 sometimes small, or large, or extremely developed, membranous, 

 or muscular, forming merely a dilatation of the oesophagus, or 

 assuming the form of a large bag having a small orifice ; the 

 stomach is very thin, or has extremely thick, firm, and power- 

 ful muscles, very small, or very large ; the intestine is long or 

 short, wide or narrow ; the coeca rudimentary, moderate, long, 

 or so highly developed as to have a greater capacity than the 

 whole intestine besides. I shall have occasion to describe 



