AMYLOID 425 



amyloid, while the inethyl-violct stain is a chemical reaction, and hence the iodin 

 reaction is much the more readily altered or lost. As Dickinson^- says, amyloid 

 stains with iodin simph' as if it absorbed the iodin more than does the surrounding 

 tissue. Krawkow believed that the methyl-violet reaction is due to the dye forming 

 a compound with the chondroit in-sulphuric acid, for he found that these substances 

 unite with one another to form a rose-red precipitate. Hanssen, however, holds 

 that the dj'es react with the protein, the iodin with some other, unknown labile 

 substance. Schmidt found that implanted pieces of amyloid lost their iodin reac- 

 tion as they underwent digestion, while the methyl-violet reaction was still very 

 distinct. ■•* It is evident, therefore, that iodin is not by itself a specific stain for 

 amyloid, especially as glycogen gives a similar reaction,** while true amyloid may 

 not react. 



Leupold** summarizes his investigations as follows: Amyloid is a complex 

 of different substances which are differentiated by micro-chemical reactions. 

 The protein ground substance of the amyloid is refractory to the typical 

 amyloid reactions. The group which is responsible for the methyl-violet reaction 

 is intimately combined with this protein substance and is separated from it only by 

 the action of alkali. The groups which give respectively the iodin and the iodin- 

 sulphuric acid reactions are closely related to each other. Nevertheless the iodin- 

 sulphuric acid reaction is a completely independent one and is not a modification 

 of the iodin reaction. The occurrence of different colors in the iodin-sulphuric 

 acid reaction depends upon different degrees of oxidation. Amyloid is an emulsion 

 colloid in the gel state. After oxidation with potassium permanganate it is 

 soluble in ammonia, NaOH and Ba (OH) 2. Conjugated sulphuric acid plays an 

 important part in the production of amyloid in the organism. The.existence 

 of large amounts of conjugated sulphuric acid produces amyloid which gives the 

 iodin reaction. The methjd-violet reaction also depends on the presence of con- 

 jugated sulphuric acid; however, for its production there must probably occur a 

 reduction in the amyloid protein. The group which gives the iodin-sulphuric acid 

 reaction occurs through decomposition and perhaps does not depend upon the 

 sulphuric acid. 



The Origin of Amyloid 



This question has not been at all cleared up as yet by the advances 

 made in our knowledge of the chemistry of amyloid substance. The 

 fact that chondroitin-sulphuric acid is a characteristic constituent 

 suggests that this bodj^ niay be liberated in considerable amount dur- 

 ing the destructive processes to which amyloidosis is usually sec- 

 ondary; this idea is further supported by the fact that amyloidosis 

 occurs particularly after chronic suppuration in bone and lungs, both 

 of which tissues, according to Krawkow, contain chondroitin-sulphuric 

 acid. This idea was not substantiated, however, by the experiments 

 made by Oddi and by Kettner,*^ who fed and injected into animals 

 large quantities of the sodium salt of chondroitin-sulphuric acid with- 

 out producing amyloid changes. Unpublished experiments of the 

 writer with the same material, as well as with ground-up cartilage and 

 with mucin, were equally unsuccessful. Likewise mice injected by 



" Allbutt's System, vol. 3, p. 225. 



"Litten (Verh. Deut. Path. GeselL, 1904 (7), 47) states that thionin and 

 kresyl-violet are the most specific stains for amyloid, which they color blue; 

 whereas methyl-violet stains red not onlv amyloid but also mucin, mast cell 

 granules, and the ground substance of cartilage. V. Gieson's stain usually colors 

 amyloid pale yellow, and hyalin red. 



** See Wichmann, Ziegler's Beitr., 1893 (13), 487. 



" Beitr. path. Anat., 1918 (64), 347. 



« Arch. exp. Path. u. Pharm., 1902 (47), 178. 



