48 PKOTEID6, 



Tlie colour is not due to the peptones or albuinoses (Kuhne). The 

 colouring matter obtained by the addition of these reagents has been 

 examined by Krukenberg : and nn>re recently by Stadelniann.- 



CLASS VII. Lardacein, or the so-called amyloid substance.* 



The substance, to which the above name is applied, is found as 

 a pathological deposit in the spleen and liver, also in nuinerous 

 other organs, such as the blood-vessels, kidneys, lungs, &c. 



It is insoluble in water, dilute acids and alkalis, and neutral 

 saline solutions. 



In percentage composition it is almost identical with other 

 proteids,* viz. : 



O. and S. H. N. C. 



24-4 7-0 15-0 53-6 



The sulphur in this body exists in the oxidised state, for boil- 

 ing with caustic potash gives no sulphide of the alkali. The 

 above results of analysis would lead at once to the ranking of 

 lardacein as a proteid, and this is strongly supported by other 

 facts. Strong hydrochloric acid converts it into acid-albumin, 

 and caustic alkalis into alkali-albumin. When boiled with dilute 

 sulphuric acid it yields leucin and tyrosin ; 5 by prolonged putre- 

 faction indol, phenol, &c. 6 On the other hand, it exhibits the 

 following marked differences from other proteids : It wholly 

 resists the action of ordinary digestive fluids ; it is coloured red, 

 not yellow, by iodine, and violet or pure blue by the joint action 

 of iodine and sulphuric acid. From these last reactions it has 

 derived one of its names, ' amyloid,' though this is evidently badly 

 chosen ; for not only does it differ from the starch group in com- 

 position, but by no means can it be made to yield sugar : ' this 

 latter is one of the crucial tests for a true member of the carbo- 

 hydrate group. According to Heschl 8 and Cornil 9 anilin-violet 

 (methyl-auiliu) colours lardaceous tissue rosy red, but sound 

 tissue blue. 



The colours mentioned above, as being produced by iodine and 

 sulphuric acid, are much clearer and brighter when the reagents are 

 applied to the purified lardaceiu. When the reagents are applied to 

 the crude substance in its normal position in the tissues, the colours 

 obtained are always dark and dirty-looking. 



1 Verhand. d. jihys.-med. GeseU. Wiirzburg, Bd. xvm. (1884), NT. 9, S. 7. 



- Zt. f. Biol. Bd. xxvi. (1890), S. 491. 



3 Virchow, Compt. Rend. T. xxxvu. p. 492, 860. 



* C. Schmidt, Ann. d. Chem. u. Pharm. Bd. ex. (1859), S. 250, and Friedreich 

 u. Kekule, Virchow's Archiv, Bd. xvi. (1859), S. 50. 



8 Modrzejewski, Arch. f. exp. Path. u. Phann. Bd. i. (1873), S. 426. 



6 Weyl, Zt. f. physiol'Chem. Bd. i. (1877), S. 339. 



7 C. Schmidt, lor. cit. 



8 Wien. med. IVochensckr. No. 32, S. 714. 



9 Compt. Rend. T. LXXX. (1875), p. 1288. 



