288 THE GROUSE IN HEALTH AND IN DISEASE 



Strongyli (1460), caught on the moor differ in certain respects (PI. XLIIL, Fig. 17). 



The muscular walls contain distinct bands of wavy, fibrous tissue. The quantity 



of fibrous tissue in the cores of the ridges seems to be increased ; but fat 



Where . . . 



worms is still present in the bifurcations. The ridges are large, and the villi 



present in . . 



healthy are markedly increased in size, especially those situated near the free 

 margins of the ridges. In the latter wavy bands of fibrous tissue may 

 be seen ; and lymphoid cells are found in considerable numbers within all the 

 villi. The epithelium appears hypertrophied, but is not markedly irregular except 

 over the villi on the free margins of the ridges. Worms are uncommon except 

 in certain situations in the depressions, where they seem to be entangled in what 

 appears to be dry, concentrated gut contents. No lymphoid follicles can be seen. 

 In a diseased Grouse (No. 6), in which the macroscopic changes are well 

 marked, the following condition is found. The muscular wall contains well- 

 in diseased mai> ked strands of fibrous tissue. The fat at the bases of the ridges 



Grouse. ^ as completely disappeared, and the vessels show considerable thicken- 

 ing of their walls. The connective tissue in the cores of the ridges is also 

 greatly increased in amount and in density, and the vessels dilated. The sub- 

 epithelial connective tissue of the villi is also increased in amount, and the 

 vessels in it dilated, and probably increased in number, and in some cases full of 

 blood. The connective tissue is in most places loose and contains large numbers 

 of cells, probably inflammatory in origin, and in some places, especially near the 

 free ends of the villi and in the neighbourhood of the worms, shows fibroid change. 

 The epithelium is proliferated and thrown into folds (PI. XLIIL, Fig. 18). 



In a Grouse (No. 15) badly infected with Strongyli, and showing well-marked 

 macroscopic lesions, all the changes just described are more evident. Much 

 fibrous tissue is present in the muscular coat, and the walls of the vessels are 

 very markedly thickened. The villi appear increased in size, and their con- 

 nective tissue is more dense, and contains a considerable amount of fibrous tissue, 

 replacing the more delicate connective tissue. In this tissue a large number 

 of the nuclei are clearly those of newly-formed fibrous tissue, being elongated 

 and spindle-shaped, though round cells are still present in considerable numbers. 

 Nuclei of the former type are now found in all situations, and are not limited 

 to the cores of the ridges as in the case of specimens from normal birds. The 

 epithelium shows great proliferative changes, and is thrown into irregular folds. 

 In all specimens from diseased birds the lymphoid follicles are indistinguishable 

 (PI. XLIIL, Figs. 19 and 20). 



