ALBUMINOUS COMPOUNDS. 59 



teristic of organization. Whether all Albuminous substances, however, must 

 pass through the condition of Fibrin, before they can be applied to the purposes 

 of nutrition, is a question which cannot as yet be determined ; and it is safer, 

 in the present state of our knowledge (or rather of our ignorance), not to dog- 

 matize upon the subject. We shall first consider the chemico-physical, and then 

 the physiological or vital properties of Fibrin. 



25. The ultimate composition of Fibrin cannot be said with any degree of 

 certainty to diifer from that of Albumen, as will be seen from the following 

 analytical results, which scarcely diifer more from those already given for Albu- 

 men, than they differ from each other : 



Scherer. Mulder. 



Carbon T /" . . . ."' ' . ' 53.6 52.7 



Hydrogen .... i 1 : 'V'"/ ;V 6.9 6.9 



Nitrogen . . -'-;V t^J.*'. v..- ;;;... --.s 15.7 15.4 



Oxygen ) (23.5 



Sulphur L . ,.,.':*..*,, ., ...v,,.* 23.8 \ 1.2 



Phosphorus J ( 0.3 



100.0 100.0 



Most of the later elementary analyses of Fibrin support the view, that there is 

 rather a larger quantity of oxygen contained in it than in Albumen ; but all 

 these results are liable to fallacy, arising from the extreme difficulty of obtain- 

 ing fibrin in a perfectly pure state; 1 and it would not be safe to rest much upon 

 them. So long as Fibrin exists in solution (as in frog's blood, diluted with 

 sugared water, and deprived of its corpuscles by filtration), it can scarcely be 

 distinguished from Albumen by the effects of reagents upon it, nearly all sub- 

 stances which precipitate the one, precipitating the other also; ether, however, 

 is an exception, for it causes fibrin to coagulate, whilst the albumen remains 

 dissolved. In its spontaneously coagulated state, Fibrin is a yellowish, opaque, 

 fibrous mass, insoluble in water, alcohol, and ether; it possesses in this condi- 

 tion somewhat of the softness and elasticity which characterize the /flesh of 

 animals, and contains about three-fourths of its weight of water. By drying, 

 this water may be expelled, and the fibrin becomes a hard and brittle substance ; 

 but, like flesh, it imbibes water again when moistened, and recovers its original 

 softness and elasticity. Fibrin in this state is remarkably distinguished from 

 coagulated Albumen, by its power of decomposing the peroxide of hydrogen, 

 on which albumen has no effect. When Fibrin is treated with strong acetic acid, 

 it imbibes the acid, and swells up into a transparent colorless jelly, which is 

 soluble in hot water; this peculiar change showing a marked difference between 

 fibrin and albumen, and indicating the relationship of the former to the sub- 

 stance of the gelatigenous tissues ( 29). Again, when treated with water 

 acidified with one-tenth part of hydrochloric acid, Fibrin swells up, and forms 

 a gelatinous mass, returning to its original volume when more acid is added, 

 and again swelling up on the addition of water, without any notable proportion 

 of it being dissolved; in this respect differing completely from the substance of 

 Muscle, which is readily dissolved by dilute hydrochloric acid. 3 Coagulated 

 fibrin, however, may be converted into a substance closely resembling albumen, 

 by means which tend to destroy its peculiar molecular arrangement. This 

 change happens, indeed, as a simple result of incipient decomposition ; for under 

 exposure to air, and with the presence of a sufficient amount of water, Fibrin 

 at first dissolves away into a substance, which, like albumen, is coagulable by 

 heat; during this process it attracts oxygen; and a continuance of the decom- 



1 See Lehmann, op. cit. p. 353. 



2 See Prof. Liebig's important Memoir on the distinction between the Fibrin of the 

 Blood and that of Muscle, in the "Annalen der Chemie und Pharmacie," Band Ixxiii. 



