"GEOUSE DISEASE "—PATHOLOGY 287 



embedded in some cementing material, which in microscopic sections appeared 

 to be composed of a mixture of mucous and granular debris, which could not be 

 removed by gentle washing. Even after free washing numerous Strongyli could 

 be seen adherent to the mucous membrane, and frequently penetrating between 

 the villi (PI. XLii., Fig. 11). In some of the worst cases the ridges are so 

 deformed as to resemble masses of coral, with smooth but irregular surfaces, 

 on which the individual villi are frequently indistinguishable, and with cave- like 

 depressions between them from which one or more Strongyli can be seen pro- 

 truding (PI. XLi., Fig. 8). These appearances, we believe, are due to the 

 matting together of the villi and sometimes of the neighbouring ridges by the 

 cementing material described above. 



With the small amount of material at our disposal ' it was impossible to 

 follow out in detail the various changes which occur in the cteca, and we 

 therefore confine ourselves to comparing the condition found in severely Histoioo-i- 

 affected birds with that found in normal birds. In the investigation of ^^ the^"^*^^ 

 the histological changes we had the advantage of the expert opinion of ^'^™' 

 Mr T. S. P. Strangeways, Huddersfield Lecturer in Special Pathology, Cambridge. 



Sections of the ctecum of the normal bird (No. 81) without Strongyli show 

 the following structures. 



There is under the peritoneum a well-marked muscular coat, and within this 

 delicate areolar tissue supporting a layer of well-formed connective tissue on 

 which the mucous membrane rests. At intervals the connective tissue 



. Normal 



layer projects towards the lumen of the gut forming the central core caecum 

 of the ridges which have been described. At their bases these pro- 

 longations appear bifurcated, and the spaces between the bifurcations are filled 

 with fat and some large blood-vessels. Both the ridges and the depressions 

 between them are covered with villi of fairly uniform length, which 



■^ . Where no 



consist of a central core of vessels surrounded by a small quantity worms 



c T T -ii-i • • present. 



of delicate sub - epithelial connective tissue, together with a few 

 lymphoid cells, covered with a single layer of columnar epithelium. Here and 

 there in the depressions may be seen sections of lymphoid follicles covered with 

 villi. The contents lying in the lumen of the gut consist of a mass of granular 

 material and mucus (PI. XLiii., Figs. 15 and 16). 



Sections of the csecum of an apparently healthy Grouse (No. 69), with many 



1 In tweuty-six specimens the contents of both caeca were used for counting the Strongyli ; and fourteen 

 specimens arrived dead and therefore useless for minute histological examination. 



