80 INTRODUCTION. 



fibrin is incapable of organization ; and it may be further 

 stated as a general law that no single proximate principle, 

 nor mere mechanical mixture of proximate principles, effused 

 into any part of the body, ever acts in any other way than as 

 a foreign substance. 



In certain instances of morbid action, effusions take place, 

 either on the surfaces of membranes, or between two opposing 

 surfaces, attaching them to each other by bridles or adhe- 

 sions, which actually become organized. This occurs most 

 frequently in serous membranes, and the structure thus 

 formed is entirely different from coagulated fibrin, which has 

 no connection with the parts, except that of contiguity. Both 

 of these formations have been included in the term, false 

 membranes; but Robin makes a very proper distinction be- 

 tween them, calling the one, which is merely coagulated 

 fibrin, like the membrane of croup, false membranes, or 

 pseudo-membranes / and the others membranes of new forma- 

 tion, or neo-membranes. The former consist simply of the 

 fibrin, which nature has been unable to remove by absorption ; 

 and the latter, of regularly elaborated anatomical elements, 

 endowed with the properties of self-regeneration common 

 to all organized structures. 



Origin and Function of Fibrin. The fibrin of the blood 

 has its direct origin, in part at least, from the albumen, by 

 the catalytic transformation which so often takes place in 

 principles of this class. It has been noticed that when fibrin 

 is increased in the blood, albumen is diminished. In some 

 experiments presented to the Society of Biology of Paris by 

 Dr. Brown-Sequard, it was shown that defibrinated blood 

 injected into the arteries of a criminal just after death, on 

 being returned by the veins, coagulated, and presented a 

 notable quantity of fibrin. 1 The remote origin of fibrin is 

 from the organic nitrogenized elements of food ; which, after 

 having undergone the catalytic changes incident to digestion, 



1 ROBIN and VERDEIL, op. cit., tome iii., p. 260. 



