574 CHEMISTRY OF THE PROTEIDS CHAP. 



to Krukenberg. 1 Attention is again drawn to the other compounds 

 described by Krukenberg, which have been mentioned on p. 554, and 

 to the substance forming the casing of Echinococcus, which has been 

 studied by Lucke. 2 



6. Amyloid 



Amyloid is generally held to be a pathological product, but 

 Krawkow 3 has shown it to occur normally in healthy aortse, and 

 occasionally also in old cartilage. Under certain pathological conditions, 

 especially those accompanied by great proteid-disintegration, it is found 

 in enormous quantities. It is found either in the form of the so-called 

 corpora amylacea in the brain and in other places, or as a diffused 

 mass in the parenchyma of the liver, the spleen, the kidney, etc., 

 whenever these organs have undergone an amyloid degeneration. 

 Amyloid was first discovered by Virchow, 4 who originally held 

 it to be a carbohydrate because of its peculiar colour-reactions, and 

 hence gave it its name. That amyloid is an albumin was first shown 

 by Schmidt 5 and Friedreich and Kekul6, 6 arid Kiihne and Rudneff. 7 

 Amyloid occurs as shiny, homogeneous masses, which, if they be present 

 in large amount, give to the affected organs a firm, almost wooden con- 

 sistency, and a peculiar greasy appearance resembling bacon. 



The colour-reactions given by amyloid are very characteristic : 



1 . With iodine + potassium iodide it is stained a deep reddish- 

 brown mahogany colour, while normal tissues appear pale yellow. If 

 amyloid stained with iodine is subsequently treated with sulphuric 

 acid or with a solution of zinc chloride, its colour is deepened still 

 more, or becomes bright red or violet or more bluish or green; 

 occasionally a violet colour is seen by simple treatment with iodine. 



2. With methyl-violet amyloid is stained a beautiful ruby colour 

 or pink or reddish violet, and not blue or bluish violet, as are normal 

 tissues. The colour-reactions of amyloid have been fully dealt with 

 by Lubarsch in the Encyclopaedia of Microscopical Technique.^ 1 



Apart from the authors mentioned above, amyloid has also been pre- 



1 F. C. W. Krukenberg, Ber. d. deutsch. chem. Ges. 17. II. 1843 (1884) ; Zeitschr. 

 f. Biol. 22. 241 (1886). 



2 A. Lucke, Virchow s Archiv, 19. 189 (1860). 



3 N. P. Krawkow, Arch. f. exper. Path. u. Pharm. 40. 195 (1897). 

 R. Virchow, Virchow's Arch. 6. 135, 268, 416 (1853). 



C. Schmidt, Liebig's Annalcn, 110. 250 (1859). 

 N. Friedreich and A. Kekule, Virchow's Archiv, 16. 50 (1859). 

 W. Kiihne and Rudneff, ibid. 33. 66 (1865). 



Encyklopddie der mikroskopischen Technik, Urban and Schwarzenberg, Berlin, 

 1903. 



