CHAPTER VI 



ANATOMY AND PHYSIOLOGY OF THE RED GROUSE 



As a preliminary to the proper understanding of the method 

 of infection in the forms of " Grouse Disease " known respectively 

 as Strongylosis and Coccidiosis certain facts concerning the 

 functional activities of the different parts of the Grouse's 

 alimentary canal should be explained. 



By the alimentary canal is meant the whole tract of the 

 digestive apparatus from the mouth to the anus or vent ; and 

 the following is briefly a history of the experiences undergone 

 by a morsel of food after it has been swallowed by a healthy 

 bird. 



In the case of the Grouse it is reasonable to take a small 

 sprig of heather, Calluna vulgaris, with a somewhat woody 

 stalk and a number of very small greenish or brownish green 

 leaves, and perhaps a few small pink flowers or shrivelled 

 flower heads containing a considerable number of very small 

 seeds. Other foods, of course, are frequently eaten, but all 

 the vegetable stuffs may be considered as partly composed of 

 soft, alterable, and digestible material, such as starch, protoplasm, 

 chlorophyll, and sap solutions, and partly of indigestible woody 

 fibres. The animal foods, whether they consist of insect or 

 mollusc, worm, crustacean or spider, can also be considered 

 as composed partly of soft, digestible material, and partly of 

 indigestible matter, such as chitin. 



And further, the function of the grit must be considered, 

 since it is as essential to the well-being of a herbivorous or 

 graminivorous bird as are teeth to the higher mammals. 



The sprig of heather is partly plucked, partly cut from the 



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