CHAPTER V 



PHYSIOLOGY AND ANATOMY OF THE EED GROUSE 



By Edivard A. Wilson 



As a preliminary to the proper understanding of the method of infection in the 

 Object of forms of "Grouse Disease" known respectively as Strongylosis and 

 chapter. 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 

 canal de- 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 vulgans, with a somewhat woody stalk and a number of very small 

 Character greenish or brownish green leaves, and perhaps a few small pink 

 eatenby Aowers or shrivelled flower heads containing a considerable number 

 Grouse. ^f 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 solu- 

 tions, 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 growing plant by 

 the beak of the bird. In captivity it is found necessary to fix the bunches of 

 heather either by tying them to the wire run or bv placing a heavv weight upon 



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