2o8 Rctrogrcssk'c Processes. 



stand out like swollen sago-grains (sago-sl^!ccii) . In the kidney 

 the substance is hkely to be deposited in the glonieruH. giving in 

 these early cases the appearance of glassy granules ; in more ad- 

 vanced cases the whole organ may. however, become waxy and firm. 

 Microscopic study shows very clearl_\- in these structures the 

 deposition just outside the capillaries and along the connective 

 tissue elements of the larger blood vessels. In the advanced 

 stages of the process the substance is seen in thick homogeneous, 

 bulging and lumpy strands. The glandular cells and connective 

 tissue corpuscles generally only suffer passively by pressure 

 atrophy, that is, they do not themselves become amyloid ; Johne. 

 however, states that in the horse the liver cells also become en- 

 larged, lobular and shining and lose their nuclei, this indicating, 

 therefore, their ])articipation in the process. 



Amyloid infiltration may also occur as a purely local process, 

 especially in the connective tissue of tumors and inflammatory 

 thickenings of mucous membranes having a substructure rich 

 in elastic tissue, as in the growths in the nasal mucous mem- 

 branes of horses known as narioblastomata. 



Finally, amyloid may be met in the form of concrement-like 

 deposits. The hyaline casts [waxy casts J forming in the urinary 

 tubules in inflammations of the kidneys sometimes show amyloid 

 reactions ; so, too, the round granules made up of epithelial 

 conglomerations and showing a concentric structure, which 

 are found in the prostate in man and in old dogs and oc- 

 casionally in the ependyma of the cerebral ventricles ( Bruck- 

 miiller. Johne). These bodies are known as corpora aniyJacca or 

 versicolorata in case they are colored brown, red and violet by 

 tincture of iodine atid sulphuric acid ; and as corpora flava when 

 they are merely turned yellow with iodine. Because of the 

 lack of uniformity of these color reactions, and because amyloid 

 substance in its earlier phases exhibits only the general charac- 

 teristics of hyaline, it is reasonable to suppose that albumens, so 

 modified as to appear hyaline, are precedents of the amyloid 

 material. 



The pathological significance of amyloid degeneration depends 

 upon the extent to which it has proceeded. Small local deposits 

 are merely incidental. In diffuse infiltration the progressive 

 character of the process, the marked increase of the volume 

 of the organ, the consequences of pressure atrophy on the paren- 

 chymatous cells, constitute the most important factors in pro- 

 duction of immediate funtional disturbance of the organ. 



