GRIT 95 



North Wales ; Blackgame from Koss-shire and Exmoor ; and Partridges and 

 Pheasants from various counties in England and Scotland. 



The gizzards of Grouse naturally received most attention ; but for purposes 

 of comparison those of other game-birds were also examined. The quantity 

 of grit found in a single gizzard varies very slightly. Samples taken Bulk of 

 from adult cocks were each found to be equal in bulk to an ounce of f^ 1 ( ! a f ( ^ md 

 shot, although, of course, much lighter, and the number of grains in s izzard - 

 each ranged from three hundred and fifty to five hundred and fifty. It was 

 also noticed that, especially in the case of Pheasants, the cock birds have a 

 larger quantity of gritty material, while the individual grains also appear to 

 be larger. This is doubtless correlated with the larger size of the si zeo f grit 

 bird, for in the smaller varieties of game - birds and in immature P artlcles - 

 individuals it is invariably found that the grains of grit are fewer and 

 smaller than in the larger and full-grown specimens. The gizzard of a chick 

 of fourteen to twenty days old was examined, and the grit was found \v e i g htof 

 to weigh 3 grains. It consisted of fragments of quartz, smooth grits- 

 and water-worn, and evidently picked up in the bed of a stream. Two only 

 were minute but perfect prisms of quartz, quite unworn. All the grains were 

 decidedly smaller than in an adult. In a half-grown chick the grit weighed 

 58 grains, while in adults the average weight is 118 to 120 grains. Grits 

 are present even in very young birds ; in one case they were found in a 

 chick only forty-eight hours old. 



The grit of an old bird can be at once recognised by the large size of 

 the grains, and by the excessive polish and smoothness of the well-worn 

 surfaces, suggesting that the larger grains are in use for a considerable period 

 of time. Between extreme youth and old age all stages of wear and polish 

 may be found as well as every gradation in point of size. 



A full analysis of the petrological character of the specimens is contained 

 in the Interim Report of the Committee ; it is unnecessary to repeat all the 

 details here, but a short summary of the general conclusions may c onst j tu _ 

 be given. As would naturally be expected the constituents of these entsof grit- 

 samples are nearly always hard rocks and minerals. Minerals or rocks softer 

 than quartz, flint, or felspar are hardly ever found ; this may be due partly 

 to selection by the bird, but it must also be borne in mind that soft substances 

 would soon be ground up by the action of the gizzard, and disappear. To this 

 also is probably due the almost complete absence of any calcareous matter, 



