THE GllEAT-CRESTED GREBE. 183 



the Podiceps cristatus this tubular prolongatiou was full of feathers, 

 which consisted of the shafts and barbs deprived of the barbules. These 

 were not wound up confusedly in a ball, but lay parallel to each other 

 and to the long axis of the tube. In the general cavity there were a 

 large quantity of feathers, many fish-bones, portions of coleopterous 

 insects, and a few pieces of the firm stems of vegetables. Some of the 

 feathers are perfect, but slightly broken ; others with the shaft and 

 barb, but without the barbules ; or the barbs alone, the shaft and 

 barbules being removed. Had I not carefully examined the gradual 

 but progressive alteration in the general cavity, I would undoubtedly 

 have said that the tubular prolongation was occupied by a bundle of 

 hairs, and not feathers, so close is the resemblance. The amount of 

 barbules in the gizzard far exceeds that of the barbs or shafts, so much 

 so, that it would require twenty times the number of feathers to pro- 

 duce an amount of barbules equal to those present. The bones in the 

 gizzard seem to be little if at all acted upon by the proventricular 

 fluid, and, from the thickness and density of the inner coat, it is pro- 

 bable that there is no secretion except that fluid. Now these circum- 

 stances deserve consideration, as they seem to imply that the proven- 

 tricular fluid, which dissolves the soft parts, has no action whatever 

 upon the bones, and that they, after being triturated, especially in the 

 tubular prolongation of the gizzard, pass onwards into the small intes- 

 tine, and there being mixed with the biliary and other secretions, form 

 the dark-coloured and friable masses found in its upper part, which, as 

 they pass onwards towards the vent, are gi'adually assimilated and con- 

 . verted into fluid excrement. 



" In the gizzard of Fodiccps ruhrlcollis there are, comparatively, few 

 feathers, and they are also less worn. There is also a less degree of 

 muscularity, and a more perfect solution of the solid parts of its food 

 by the proventricular fluid. From the preceding obseiTations I infer 

 that the feathers perform a threefold office. First, as a protecting 

 medium, to defend the epidermic coat from laceration by the sharp 

 edges and points of the fish-bones. Secondly, as a triturating appa- 

 ratus. Thirdly, as a filter, the tubular prolongation allowing the fluids 

 and triturated bones to pass into the intestine, whilst the coarser por- 

 tions arc retained, to be subjected to further action." 



