BLOOD. 359 



in cold water. When thus dried 100 parts of albumen were re- 

 duced to 25 parts. 



Albumen combines both with acids and bases. It is pre- 

 cipitated in grey flocks by tannin. 



2. Fibrin. When the crassamentum of blood is put into a 

 linen cloth, and carefully washed till all the red colouring matter 

 is removed, the substance which remains has received the name 

 ofjibrin. When moist it is white, soft, and composed of long 

 fibres or threads. Hence the reason of the name, which seems 

 to have been first imposed by Fourcroy and Vauquelin. 



It was long the opinion of physiologists, that the globules of 

 the blood consisted of a nucleus of fibrin inclosed in a vesicle of 

 colouring matter. Hence was inferred the reason why it exists 

 in the crassamentum. But later observations have considerably 

 modified this opinion. Piorry and Scelles de Mondezert have 

 remarked, that if we cautiously and rapidly remove the serum 

 which floats upon the crassamentum, we will frequently find it 

 become opaline and muddy, and finally, it is covered with a skin 

 analogous if not identical with fibrin.* According to Muller, if 

 we amputate the thigh of a frog, and mixing the blood with an 

 equal quantity of water, holding sugar in solution, throw the 

 whole upon a moistened filter, the red globules, which are very 

 large in that animal, are retained upon the filter, while a colour- 

 less and clear liquid passes through. In this liquid a coagulum 

 of fibrin speedily appears. 



From these facts there seems no reason to doubt that the fi- 

 brin exists in the serum as well as albumen ; and that the glo- 

 bules consist of a red colouring matter, and a white insoluble 

 substance, the nature of which has not been ascertained ; though 

 in all probability it is analogous to coagulated albumen or fibrin. 

 Indeed, Lecanu has shown by numerous experiments, that the 

 globules consist essentially of three distinct substances, namely, 

 hematosin, albumen, and fibrin. f 



Fibrin may be procured likewise from the muscles of animals. 

 Mr Hatchett cut a quantity of lean beef into small pieces, and 

 macerated it in water for fifteen days, changing the water every 

 day, and subjecting the beef to pressure at the same time, in or- 

 der to squeeze out the water. The u shreds of muscle, which 

 amounted to about 3 Ibs., were now boiled for five hours every 



* Lecanu, p. 43. f Ibid. p. 50. 



