288 VIRCHOW, ON THE CELLULOSE QUESTION. 



matters. The corpora amylacea of the nervous centres, both 

 morphologically and chemically, approach the nearest to the 

 amylox-granules of plants. They have the same concentrically- 

 striated structure, the comparatively strongl}- -reflecting sur- 

 face, the bluish colour, upon the simple application of iodine, 

 and lastly, their swelling in hot, and their ultimate solution, 

 although with chemical change, in boiling water. Busk even 

 says, what Donders and myself have been unable to perceive, 

 that some of the smaller corpora amylacea exhibit, in polarized 

 light, a sharply-defined dark cross, the lines forming which 

 decussate in the centre of the granule at an angle of 45°, 

 though it must be allowed that most of them exhibit only a 

 single dark line. The same observer also believes that in 

 one case he perceived minute particles of the amyloid sub- 

 stance enclosed in cells, whose cavity they only partly oc- 

 cupied. 



Widely different from the above is the amyloid degeneration 

 of the vessels, of the connective tissue, and of the cells in the 

 spleen, liver and kidney. In these situations I have never 

 obtained a blue, nor even a bluish colour, by the addition of 

 iodine alone ; on the contrary, the peculiar yellowish-red is 

 exhibited, which has from the first surprised me (vol. vi., 

 p. 269), and which Meckel has since described as " iodine- 

 red," and proposed as a characteristic of his lardaceous sub- 

 stance. But at the same time care must be taken with respect to 

 this, since, especially all parts containing blood, often assume a 

 very similar appearance. At present it appears to me that 

 we are in no case justified in admitting the existence of 

 an amyloid substance, where a violet-blue or bluish-green 

 colour is not produced upon the subsequent addition of sul- 

 phuric acid or of chloride of zinc. But in all such cases it is 

 advisable by the simple addition of concentrated sulphuric 

 acid, to satisfy oneself that similar colours are not produced 

 by that reagent, as may very well be the case, especially in a 

 series of animal colouring matters. 



Whether the yellowish-red, or iodine-red appearance of the 

 parts indicate any specific substance, is still to be shown. 

 Busk seems inclined to compare with it a kind of immature 

 cellulose, such as is said to occur in the lower plants. In any 

 case, however, the deposition of the substance presents a close 

 resemblance to true lignification — the formation of cellulose 

 in plants. But in the vegetable kingdom, as is well known, 

 the most numerous combinations of cellulose with nitrogenous 

 substances are met with, so that, as Mulder in particular has 

 shown, on the addition of iodine with sulphuric acid all sorts 

 of impure colours are presented, constituted of a mixture of 



