ANATOMY AND PHYSIOLOGY OF RED GROUSE 169 



litmus unnecessary. The juices of the berries are red, and stain 

 the tissues red wherever the acidity is not overcome by alkaline 

 digestive juices. But wherever there is a slight alkalinity in 

 the juices there the tissues are stained bluish. 



In the convoluted intestine the food is in a somewhat fluid 

 state ; and as the mere presence of convolutions in the intestine 

 of any animal are evidence of the necessity for a retarded 

 passage, the function of the convolutions in this case is obviously 

 to hold the mixture for a sufficient length of time at a certain 

 regular temperature to enable the active digestive ferments 

 to complete their work upon the food-pulp. The heather 

 fragments are thus altered into a solution of digestible food 

 and indigestible refuse of woody fibre. The former is now ready 

 for use by the tissues of the body as soon as it can be brought 

 to them by the agency of the circulating lymph and blood. 

 Certain harmful and poisonous products will also unavoidably 

 appear in the Grouse's intestine as they do in the human intes- 

 tine and in the intestine of every living animal from time to 

 time, even in the ordinary course of digestion. These, as in 

 the human body, having been absorbed with the soluble food 

 supply into the blood are then eliminated, chiefly in their passage 

 through the liver, before the mixture of good and evil products 

 can be thrown upon the general circulation. The liver in man 

 is the great eliminator of poisons produced in the intestine, 

 and the liver in the Grouse almost certainly acts in a similar 

 way. 



By the time the food reaches the lower and straighter portion 

 of the small intestine it is seen that much of the fluid has dis- 

 appeared, the contents are becoming more and more thickened, 

 and are now converted into a semi - fluid paste intermixed 

 with woody particles. By the time that the contents reach 

 the junction of the small intestine with the rectum they have 

 been still further prepared for separation. At this point 

 the caecal appendices or caeca (PI. xvi.) open into the 

 main gut. Each caecum measures from 30 to 36 inches in 

 length. Their colour in health is a dull drab grey, while 



