LECTURE XVII. 



Essentially different from this separation of starch-like 

 matter, which lies between the elements, are the degene- 

 rations of the tissues themselves, in which all their con- 

 stituents (parenchyma and interstitial tissue), as such, 

 become directly filled with a substance also of an amy- 

 loid nature, and are gradually infiltrated with it just as 

 tissues become infiltrated with lime in calcification. No 

 two things can be more justly compared than calcification 

 and the amyloid change (lignification). This (amyloid) 

 substance, which produces the real degeneration of the 

 tissue, exhibits the peculiarity, that it never becomes blue 

 under the influence of iodine alone. At least no case is 

 as yet known, in which the substance has yielded this 

 colour with iodine in the parenchyma of tissues. On the 

 contrary, a peculiar yellowish red colour is seen to arise, 

 which it is true in many cases has a slight tinge of red- 

 dish violet, so that a certain approximation is manifested 

 to the blue of real starchy matter. On the other hand, it 

 displays pretty regularly a real, either perfectly blue, or 

 violet colour, when the application of iodine is followed 

 by the very cautious addition of sulphuric acid. A certain 

 degree of practice indeed is requisite ; the exact propor- 

 tion must be hit upon, inasmuch as the sulphuric acid 

 generally destroys the substance very quickly, and either 

 very indistinct colorations are obtained, or the colour 

 manifests itself only for a moment, and then immediately 

 disappears again. Thus this substance is less nearly allied 

 to starch properly so-called and more akin to cellulose, as 

 I have already described it (p. 31). But from cellulose 

 again it is also distinguished by the fact of its becoming 

 coloured upon the application of pure solution of iodine, 

 whilst real cellulose is not at all coloured by iodine alone. 

 Cellulose behaves precisely like cholestearine which re- 

 mains colourless when treated with iodine, but on the 



