CHEMICAL COMPOSITION OF THE BODY. 



87 



PROTAGON, which Liebreich and Bayer' regarded as a constituent of nerve- 

 tissm 1 , is stated by Frey to be a mixture of Cerebrin and Lecithin. 



[J. L. W.Thudk'hum says that nerve-matter contains an abundance of water 

 termed " water of colloidation." He says there are three groups of nerve- 

 matter in the brain : phosphorized bodies, nitrogenized bodies, and oxygen- 

 ized bodies. Phosphorized bodies contain the phosphorus in the .shape of 

 phosphoric acid, proximately combined with glycerin; and they may be 

 subdivided as follows: kephalins, which have a free affinity for oxygen; 

 myelins, which have none, and lecithins. The nitrogenized bodies imitate 

 the phosphorized, but in a lesser degree, and are cerebrin, phreuosin, and 

 kerasin. The oxygenized bodies consist mainly of alcohols. Jour, of Physi- 

 ology.] 



MYELIX. The term My el in was applied by Virchow 2 to the substance 

 which constitutes the medullary portion of the nerves, but which he, Gobley, 

 and others, also obtained from the blood and bile, spleen, thymus gland, the 

 yolk of egg, the testes and spermatic fluid of the bull, and the ovary of the 

 calf. It is a viscid substance, assuming a variety of forms, that present the 

 most deceptive resemblance to nerve-fibres. It is easily soluble in. ether, 

 chloroform, turpentine, and hot alcohol, but separates from the latter on 

 cooling. In water it swells up like'sago. It is only slowly decomposed by 

 acids or alkalies. Beneke 3 observing that myeliu gave a red color with 

 sulphuric acid and sugar (Pettenkofer's test) regarded it as the glyceride of 

 cholic acid, and considered the presence of cholesterin to be a necessary 

 condition of its production, and both he and Neubauer 4 obtained forms simi- 

 lar to myelin from an emulsion of cholesterin in soap and water, and from 

 a mixture of oleine, ammonia, and water, and it seems very doubtful whether 

 it can be regarded as a true chemical compound of constant composition. 



AMYLOID SUBSTANCE. A peculiar form of degeneration sometimes takes 

 place in certain tissues and glands, known as waxy degeneration, in which 

 a homogeneous dull gray substance is deposited differing from other albu- 

 minoid compounds in turning of a bluish violet, or mahogany red color, 

 when acted upon by iodine. In some instances corpuscles are met with re- 

 sembling starch-grains in presenting concentric striatiou. These laminated 

 concretions are believed by Eiudfleisch 3 to be the result of successive de- 



FIG. 43. 



Myelin. 



Leucin. 



posits of fibrin in cells, or on hremorrhagic deposits or other normal or ab- 

 normal elements of the tissues. 



LEUCIN, C 6 H 12 N 2 O 2 , or Amido-caprouic acid, C B O n (]S". 2 H) 2 , appears in 

 the form of iridescent scales, which are made up of fine microscopic needles, 



1 Virehow's Archiv, Band xxxix, 1867, p. 183. 2 Ib., Band vi, p. 562. 



3 Studien iib. d. Vorkom. v. Gall, in Thier. u. Pflanz, 1862. 



4 Beneke, in Archiv f. wissensch. Heilkunde, 18G5, p. 375; and Neubauer in Vir- 

 chnw's Archiv, xxxvi, p 303. 



* Pathological Histology, Syd. Soc. Trans., 1872, p. 44. 



