120 THE GROUSE IN HEALTH AND IN DISEASE 



(5.) There may be appearances of recovery. In a good many birds the 

 caecal mucosa is dotted all over with minute black pigment granules, in other 

 words some of the villi show no blood-vessels injected, but are filled with 

 pio-ment granules instead. These are sometimes so abundant as to colour the 

 gut. They lie in the villi in great numbers (see Plate xxxr., Figs. 7 and 8). 



It is possible that they result from previous chronic congestion and 



that there are circumstances under which the bird may rid itself of an 



excessive number of Trichostrongylus. If there is any plant 



Possibility . in 



of recovery which acts as a vermifuge to this nematode on the Grouse moor, 

 strongy- aud if it could be discovered and encouraged to grow one cannot 

 help thinking that the Grouse might learn to eat it. If this 

 supposed recovery from Strongylosis has not resulted from some unknown 

 vermifuge herb, then it must have resulted from improved conditions of 

 life ; and the one condition of life which is in the hands of the moor pro- 

 prietor is the food supply. It thus becomes imperative to give every Grouse 

 on the moor the best possible chance of overcoming the parasitic pest which 

 produces what is probably the most harmful feature of the disease, namely 

 the chronic congestion of the villi of the cseca. Improve the conditions of 

 life, improve the circulation so that the heart and lungs work more efficiently, 

 and the digestion automatically improves, as also does the elimination of 

 toxins, whether produced by the parasitic worms, or by the food eaten, or by 

 bacteria in the gut. The worms, one must suppose, remain in the gut ; 

 but the congestion is overcome, and the bird is not very much the worse 

 for their presence. But, if the congestion is allowed to continue and become 

 chronic, the digestion and absorption of food must go from bad to worse, 

 and with it every other function of the body. Nothing will prevent the bird 

 in this case from losing its weight, and eventually its life. 



As for the exact cause of the congestion, it may be due to mechanical 

 constriction of the filamentous processes of the villi by the nematode worms. 

 The iin- Each time the gut acts peristaltically the worms have to hold on 

 caule'of tightly to the mucosa or else be dislodged with the dejecta, and 

 congestion, ^j^g rcsult is sGcu in sections where the villi are evidently mixed 

 up inextricably with the coils of Trichostrongylus. Or it may be due to the 

 chemical irritation of some poison produced in the gut by the worms, or by the 

 defective digestion of food stuffs, or by bacteria living in the gut in its unwhole- 

 some state. Or it may be due to some or all of these conditions together. 



