116 THE GROUSE IN HEALTH AND IN DISEASE 



bad case of Helminthiasis, with intussusception ; the caeca also were 

 intensely congested and very much thickened, the lower third especially was 

 blood - red, and full of Trichostrongylus. The duodenum also was much 

 inflamed, and for a male the weight, 15f ounces, was, of course, exceedingly 

 small, showing that it had suffered severely in its struggle with so many 

 parasitic worms. Of this condition, therefore, one might expect well-marked 

 post-mortem evidence. The intussusception was probably the result of great 

 irritation. 



The only pathological appearance which is commonly seen in the rectum of 

 the Grouse is a reddening along the glandular ridges, due to villous engorge- 

 ment. This appearance is illustrated on PL xxix. where Fig. 2 



Inflamma- . 



tionof shows the rectum in a normal healthy condition. Jig. 3 shows the 

 same when inflamed throughout its length. Fig. 4 shows the rectum 

 with the posterior third very much inflamed. Fig. 5 represents the punctiform 

 injection of the villi, while Fig. 6 shows the same injection when magnified under 

 a 1-inch objective. The cause of this villous engorgement is obscure, but it is 

 much more frequently found about the lower third of this portion of the gut 

 than about the upper two-thirds, though it may be general throughout the 

 rectum. It does not appear to be dependent upon disease or sickness, though 

 apparently sometimes it has some relation with an excessive number of tape- 

 worms in the main gut. 



In the caeca of the Grouse lies the whole origin and cause of " Grouse 

 Disease" in the adult bird. In these blind guts lives Trichostrongylus 

 pergracilis, and these, when present in enormous numbers, produce 

 an excessive amount of irritation and congestion of the vessels and of the 

 Tricko- capillaries in the villi, desquamation of the endot helium, and so much 

 strongyius. disturbance of the proper functions of this portion of the gut that 

 the contents, consisting of food, mucus, nematode worms, and nematode ova 

 in a pasty and decomposing mess, not only become useless as food, but a grave 

 danger to the bird owing to the amount of toxins produced and absorbed into 

 the circulation. The internal appearance of the normal caecal mucosa is shown 

 on PI. xxx., Fig. 1, which represents a section of the caecum of a healthy 

 bird ; the nodules and granular ridges are yellowish, and the interstices are dark 

 reddish brown. The external appearance of the normal healthy caecum as it lies 

 in the body of the Grouse is seen in PI. xxvu., Fig. 1 (i). But when badly 



