104 ON THE ELEMENTARY PARTS OF THE HUMAN FABRIC. 



It is not, perhaps, of any great moment whether this difference has a real 

 existence or not; for the conversion of Albumen into Fibrine is unquestion- 

 ably a process much more of vital than of chemical transformation. We 

 shall presently see, that Fibrine may be regarded as Albumen, in which the 

 process of Organization has begun ; its molecules being ready to assume the 

 peculiar arrangement that is so designated : this arrangement takes place 

 most completely, when the fibrinous mass is in contact with a living tissue, 

 and is therefore to a certain degree under its influence. Fibrine, like Albu- 

 men, may exist in a sohible or in a coagulated state ; its soluble form only 

 occurs, however, in certain living animal fluids, the Chyle, Lymph, and 

 Blood; and it seems to be the intermediate condition between the soluble al- 

 bumen, and the solid organized substances which are formed from it. When 

 withdrawn from the blood-vessels, the Blood soon coagulates, as do also the 

 Chyle and Lymph, when they contain sufficient fibrine ; and this coagulation 

 is entirely due to a change in the condition of the Fibrine, the particles of 

 which have a tendency to aggregation in a definite manner. The Fibrine may 

 be obtained in a separate form, by stirring fresh-drawn blood with a stick, to 

 which it adheres in threads ; these contain some fatty matter, which is to be 

 washed out with alcohol. In this condition it possesses the softness and elas- 

 ticity which characterize the flesh of animals; and contains about three-fourths 

 of its weight of water. It may be deprived of this water in dry air, and then 

 becomes a hard and brittle substance ; but, like flesh, it imbibes water again 

 when moistened, and recovers its original softness and elasticity. When 

 burned, it always leaves, like albumen, a portion of phosphate of lime. Fi- 

 brine is insoluble in alcohol and ether, and also, under ordinary circumstances, 

 in water; but when long boiled in water, especially underpressure, its nature 

 is altered, and it becomes soluble. This change, which may be effected also 

 in coagulated Albumen, is attributed by Mulder to the oxidation of the Pro- 

 teine, which is its principal constituent ( 116, ). When Fibrine is treated 

 with strong acetic acid, it imbibes the acid, and swells up into a transparent 

 colourless jelly, which is soluble in hot water; this solution is precipitated by 

 the addition of another acid. 



115. Fibrine, like Albumen, unites with acids as a base, forming definite 

 compounds ; and with bases as an acid. Its correspondence with Albumen 

 is further indicated by the fact (first stated by M. Denis), that it may be en- 

 tirely dissolved in a solution of nitrate of potash; and that this solution is 

 coagulated by heat, and greatly resembles a solution of Albumen. This is 

 only true, however, of the ordinary Fibrine of venous blood; for that which 

 is obtained from arterial blood or from the buffy coat, or which has been ex- 

 posed for some time to the air, is not thus soluble. This is an important and 

 interesting circumstance. The difference appears to depend upon the larger 

 quantity of oxygen contained in the latter; for a solution of Venous Fibrine in 

 nitre, contained in a deep cylindrical jar, allows a precipitate in fine flocks to fall 

 gradually, provided the air have access to the surface, but not if it be prevented 

 from coming in contact with the fluid ; this precipitate is insoluble in the solution 

 of nitre, and possesses the properties of arterial fibrine. Hence it may be 

 inferred, that the Fibrine of Venous blood most nearly resembles Albumen ; 

 whilst that of Arterial blood, and of the Buffy coat, contains more oxygen, 

 and is more highly animalized. When decomposition commences in a coagu- 

 lum of Fibrine withdrawn from the body (and even in the greatly-debilitated 

 living body, in which the Fibrine appears to be imperfectly formed), a granu- 

 lar mode of aggregation is evident in the particles of the mass, thus showing 

 its affinity to Albumen, when its peculiar vital characters have departed, or 

 are possessed by it in an inferior degree. 



116. The close chemical relation existing between Albumen and Fibrine 



