2o6 Retro o^rcssk'c Processes 



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to that of starch [when treated with iodine alone], and which is 

 found in the tissues as the result of a special process of meta- 

 morphosis. 



[The editor is accustomed to regard the process not as a 

 metamorphosis or true degeneration as here indicated, but rather 

 as an infiltrative process. The reasons for this view are, it is 

 true, not absolutely convincing, but are suggestive. The material 

 may in accordance with this idea be supposed to exist in the 

 blood or elsewhere in a soluble pre-amyloid state and to be car- 

 ried by the blood to be deposited in its favorite seat, the walls 

 of arteries, where for some unknown local cause it is precipitated 

 as amyloid matter. Its common occurrence in the walls of arte- 

 ries rather than those of veins, its appearance in masses in inter- 

 cellular positions Avhere normally there scarcely exists material 

 which could b}- any known mode of transformation assume the 

 size of the common amyloid masses (as between the basement 

 membrane and epithelium of the renal tubules), are the jirincipal 

 basis for this opinion.] 



When unstained, amyloid substance is, like hyaline or colloid, 

 of a glass-like, homogeneous appearance, and is principally found 

 deposited in the connective tissue framework of the blood vessels 

 in afifected organs as lumpy, swollen-looking, trabecular or clump- 

 like masses. While, however, the hyaline above discussed is 

 tinged like the tissues themselves a yellow straw color by iodine ; 

 amyloid substance takes a mahogan}-brown tint, sometimes with 

 a violet tone, and stands out conspicuously from the tissue. If 

 dilute sulphuric acid or zinc chloride be applied to such a prep- 

 aration, the amyloid substance takes on a deep violet to black 

 color ; its reaction being thus somewhat similar to that of starch 

 granules or cellulose, these, however, becoming blue directly on 

 the application of iodine alone. Other color reactions, charac- 

 teristic of amyloid substance, are given by various aniline dyes ; 

 methyl-violet staining it a ruby red, methyl-green a reddish 

 violet, in contrast to the bluish violet or green color given the 

 normal tissues. Amyloid is colored yellow by nitric acid, indi- 

 cating by this xanthoproteic reaction its albuminous nature. 



According to the investigations of Kraw'kow this substance is 

 a compound of an albuminate with chondritin-sulphuric acid. 

 This latter substance, to which the iodine reaction is mainlv due 

 (Ribbert) is found normally in cartilage and elastic tissue. 

 Amyloid material, as such, does not exist normally in any part 



