NITROGENOUS OEGANIC CELL-CONSTITUENTS. 103 



appears to be a derivative of fibrin, and is found as a deposit in numerous 

 of the organs of the body, such as the spleen, liver, etc. It is insoluble 

 in water, alcohol, ether, dilute acids, and alkaline carbonates, and is not 

 dissolved by the digestive juices. When acted on by concentrated hydro- 

 chloric acid it passes into solution and is converted into syntonin, which 

 may be precipitated by dilution with water. With sulphuric acid it dis- 

 solves when boiled, forming a violet solution, and with strong sulphuric 

 acid it is converted into leucin and tyrosin. In its composition it appears 

 identical with other proteids. It behaves differently, however, to certain 

 of the proteid tests, and must, therefore, be regarded as a modified 

 proteid. Thus, with iodine, instead of the yellow color produced with 

 other proteids, a reddish-brown color is formed. With iodine and 

 chloride of zinc or sulphuric acid a violet-bluish color is produced, thus 

 resembling cellulose in its reaction, to which similarity it owes its name 

 of amyloid, though it must be remembered that this is the only point of 

 similarity between amyloid substances and the starchy bodies ; for it 

 contains nitrogen, which is absent from all starches, and it cannot be 

 converted into sugar. Aniline violet on amyloid substance causes a 

 reddish-violet color, and is a test which may be readily used for detecting 

 the presence of amyloid degeneration in various animal organs. Amyloid 

 substance yields the Millon's and xantho-proteic reactions. 



VII. Peptones. — A peptone is a modified form of proteid which 

 occurs when any of the albuminous bodies, with the exception of lardacein, 

 are subjected to the action of gastric or pancreatic juices, prolonged 

 boiling at high temperature under great pressure, or by the action of 

 heat and dilute acids at moderate temperature. Their general charac- 

 teristics will be referred to under the subject of Digestion. 



In addition to the above classes of albuminous bodies, albumen has 

 been said to exist under two other forms, that of meta-albumen and para- 

 albumen, although as yet very little is known about their characteristics, or 

 in fact whether they are not simply ordinary albuminous bodies modified by 

 the accidental addition of some other substance. Thus, meta-albumen 

 might possibly be regarded as a mixture of albumen and mucin, since it is 

 precipitated by alcohol without undergoing coagulation ; it is not coagu- 

 lated by boiling, although its solutions become cloudy when heated, and 

 it is not precipitated by acetic or hydrochloric acids, or acetic acid and 

 potassium ferrocyanide. It is, however, precipitated by mercuric chloride 

 and gallic acid. It has been found in ovarian cysts, and in the fluid of 

 ascites. When precipitated by alcohol the precipitate is again soluble in 

 water. Para-albumen has also been found in the fluid of ovarian cysts, 

 where its presence was supposed to be characteristic, but has also been 

 found elsewhere. It is precipitated by alcohol, and when so precipitated 



