64 PHILOSOPHY OF ZOOLOGY. 



which remains is more copious than that which is left by 

 the two preceding substances. It is incinerated with difficul- 

 ty, as a glassy coating forms on its surface, and excludes the 

 action of the air. The residue consists of the phosphate of 

 soda and lime, together with carbonate faf lime. Fibrin 

 we have seen, exists in the blood, and was formerly calle_ 

 the fibrous part of the blood. It likewise exists in all 

 muscles, forming the essential part or basis of these organs. 

 It exhibits many remarkable varieties, as it appears in the 

 flesh of quadrupeds, birds and fishes. 



4. Extractive.* When the flesh of an animal is boiled 

 for some time in water, the fibrin and albumen remain, 

 and the solution contains the gelatine and other substances 

 soluble in water. If the solution be evaporated to dryness, 

 and treated with alcohol, the gelatine remains undissolved, 

 and a solution of extractive is obtained. It is the sapona- 

 ceous extract of meat of ROUELLE, and the osmazome of 

 TIIENARD. 



When freed from the alcohol by evaporation, the ex- 

 tractive is of a reddish-brown colour, semitransparent, has 

 an acrid taste, and an odour similar to the juice of meat. It 

 attracts moisture from the air, and becomes soft. It is so- 

 luble in alcohol and water. It is precipitated by the in- 

 fusion of nut-galls. When heated, it swells, and emits 

 the odour of burning animal matter. Its charcoal affords 

 carbonate of potash. When distilled, it yields ammonia. 

 Its constituent principles appear to be the same with those 

 of the three preceding substances. According to BERZE- 

 LIUS, it is always combined with the lactate of soda *. 



Extractive exists in the muscles of animals, in the blood 

 and in the brain. It communicates the peculiar flavour 

 of meat to soups. In the opinion of FOURCROY, the 

 brown crust of roasted meat consists of it. 



* Annals of Phil. ii. p. 202. 



