102 THE GEOUSE IN HEALTH AND IN DISEASE 



were found distinctly wet, were, without exception, in birds showing definite 

 signs of sickness, and in sickness there is no doubt that the bird 



Drinking , . . . -i i i. 



habits of secks Water and often drinks it. It is, however, very possible that 

 water is swallowed straight into the proventriculus, passing by without 

 entering the opening into the crop. If this be so, too much stress must not 

 be laid on the dryness of the food in the crop, in considering the drinking 

 habits of the bird. 



But with food in the crop, and there is no hour in the day when the 

 crop may not contain some food, all the evidence afforded by an examination 

 of many hundreds of crop-contents goes to prove that water is not freely 

 taken, or if taken, is not admitted to the crop. Probably, when there is 

 food in the crop, no water is drunk, for there is no general condition of 

 wetness at any time either in the crop or in the proventriculus, or in the 

 gizzard, all of which are occupied in turn by the gradual passage downwards 

 of the morsels of food collected in the crop. 



In the proventriculus, as has been said, the bits of food, coated now with 



a tenacious and slightly acid mucus, are passed into the muscular gizzard 



(Pis. XXVI. (g.), xxvii., Fig. 1 (c), xxvii.a, xliv.), a familiar object 



Gizzard. . .... 



m the anatomy of the common fowl, and an organ oi very similar 

 shape and of equal muscularity in the Grouse. Its walls are very thick, and 

 the muscles which compose them act from tendinous sheets, into which they are 

 firmly fixed. The cavity of the gizzard is comparatively small, and is lined with 

 a very tough resistant lining membrane of fibrous tissue, and contains about 

 a teaspoonful of small hard subangular or rounded grains of hard rock. 



The substance almost universally chosen by the Red Grouse is quartz, and 



although on the moor, as in captivity, the bird will swallow any small portion 



of hard material which comes in its way, quartz is most suitable, 



not only for the Grouse but for every other graminivorous bird 



in health. A very extensive collection of Grouse's gizzard grits has been 



^ , made by the Committee, and carefully examined, and the result 



Quartz •' ' J ' 



most shows the variety of material of which a Grouse will make use when 



common. _ •' 



quartz is not locally abundant.' But the point conclusively proved 

 is that quartz, both on account of its hardness and its method of fracture, 

 is the gizzard grit most abundantly used by Grouse. The subject of 

 gizzard grit is more fully dealt with in chapter iv. 



' Vide chap. iv. p. 9.5. 



