168 THE GROUSE IN HEALTH AND IN DISEASE 



ramify over the peritoneal surface are almost invisible. 

 The pancreas also should be pale creamy white or faintly 

 pink. 



The alkaline mixture now passes from the duodenum into 

 the convoluted upper portion of the small intestine (PI. xvi.). 

 This extends from the lower end of the duodenum to the 

 upper end of the rectum (PL xvi.), where the two caeca 

 enter it. The small intestine measures in all 35 inches, but 

 there is a distinction to be made between the upper con- 

 voluted portion and the lower straighter portion (PI. xvi.), 

 for the convoluted portion is freely movable, whereas the 

 straight portion is so intimately folded with the long caecal 

 appendices, and so closely bound together with them in a 

 common mesentery as to be very limited in its movement. 

 The various parts of the lower intestine are shown laid out 

 in the accompanying diagram (PI. xvi.). 



Returning, however, to the changes which are being ex- 

 perienced by the particle of food in question, as it passes from 

 the duodenum into the convoluted portion of the main gut, 

 it is first noticed that the duodenal tapeworm, Hymenolepis 

 microps, wholly disappears, and that its place is taken by the 

 much larger and more conspicuous tapeworm, Davainea 

 urogalli, often in such quantity that the outward appear- 

 ance of the small intestine is altered to a swollen, bulky 

 gut of a creamy white colour due to the enclosed mass of 

 white tapeworms shining through its thin and distended walls. 



It has already been noticed that the neutral or faintly acid 

 reaction of the contents of the duodenum has gradually changed 

 to a more and more markedly alkaline reaction. Hymenolepis 

 affects a neutral medium, and Davainea an alkaline medium. 



These changes in the character of the intestinal contents 

 can, of course, be easily tested by the use of litmus papers ; 

 but when a Grouse, which has been feeding upon ripe Blaeberries, 

 Cranberries, or Crowberries with coloured juices, is examined, 

 the contents of the alimentary canal of the bird itself are found 

 to be coloured within from end to end, in such a way as to make 



