PHYSIOLOGY AND ANATOMY OF RED GROUSE 109 



ceivable that after full feeding in the evening the Grouse jugs in the heather, 

 and the process of digestion and the action of the intestine proceed until there is 

 a large quantity of hard and soft food in the lower part of the small intestine 

 ready for selective absorption and separation. This separation probably proceeds 

 all night, the soft material constantly passing into the caeca, and the harder 

 waste matter passing on as constantly into the rectum and out at the vent. 



Then, early in the morning the action is reversed, the passage of food down 

 the main gut ceases because the supply from above has been stopped during the 

 night when, of course, nothing has been eaten. The useful part of the csecal 

 contents has now been absorbed, and is circulating in the blood, and the caecum 

 therefore contracts downward and expels all the waste matter that is in it. 

 This is borne out by what one sees upon the moor, by the absence of caecal 

 excreta amongst the heap of formed droppings passed in the night, and by the 

 occasional appearance of some caecal excreta on the top of these heaps, though 

 more frequently in their near neighbourhood or near the early morning drink- 

 ing and feeding resorts. There is, moreover, now no doubt that the 

 Grouse feeds more or less all day ; but, as a rule, the crop is found fullest times of 



. Grouse. 



in the evening. Probably digestion is sufficiently rapid during the day 

 to deal with the food almost as fast as it is picked and swallowed. It may be 

 that the caecum receives matter both by day and by night, and discharges its 

 contents only in the early hours of the morning ; but these details are not easy 

 to determine in the wild bird, though it is easy to see how indispensable it is to 

 the well-being of the Grouse that the caeca, whose combined length nearly equals 

 that of the rest of the alimentary tract, and which are responsible for the 

 absorption of most of its food, should be in good working order. It importance 

 seems impossible to exaggerate their importance in the bird's economy, of 08eca - 

 for if they are put out of action the bird may eat as much as ever and yet rapidly 

 lose flesh by sheer starvation. It may suffer even worse things owing to the 

 decomposition of the food and the diminished powers of selection during Danger of 

 absorption, thus causing toxaemia. That this happens is evident, for tox8enua - 

 it is a very usual occurrence to find the caeca in a case of Strongylosis, com- 

 pletely filled by a semi-dried mass of foul, caecal matter adhering to the mucosa, 

 leaving very little room down the centre for the passage of anything at all. In 

 such cases the Trichostrongylus is usually excessively abundant, and may Tricho- 

 be seen bridging the space by hundreds between the adherent faecal mass 

 and the mucosa from which the latter is being forcibly separated in dissection. 



