SOLID PARTS OF ANIMALS. 



The portion of brain which had been digested in ether was next 

 treated with boiling alcohol repeatedly, as long as any white matter 

 was deposited, when the alcohol cooled. This white matter was 

 cerebrate; the substance which had been already obtained by 

 Vauquelin by a similar process, and which he had distinguished 

 by the name of cerebral matter. 



The brain deprived of these fatty matters has not materially 

 changed its appearance or its bulk. Vauquelin has shown that 

 this neurilema contains albumen and coagulated globules of a 

 membranous substance, soluble in potash. This substance, when 

 dried, assumes a gray colour, a semitransparence, and a fracture 

 similar to that of gum arabic. When put into water it becomes 

 opaque, swells up and softens, and water dissolves a very small 

 portion of it. Thus softened it readily dissolves in caustic potash 

 by the assistance of heat, and during the solution no ammonia 

 is disengaged. The potash solution is slightly brown, and has a 

 weak smell. The acids throw it down in white flocks, and dis- 

 engage a very fetid odour. When acetate of lead is dropt into 

 the solution, a dark brown precipitate falls, showing the presence 

 of sulphur. When cautiously distilled, it furnishes carbonate 

 of ammonia in crystals, and a red oil similar to that which al- 

 bumen yields when treated in the same way. 



According to Vauquelin, the medulla oblongata and spinalis 

 are of the same nature with the brain, but contain much more 

 fatty matter, and less albumen, osmazome, and water. Hence, 

 the reason why the spinal marrow has greater consistence than 

 the brain. The portion insoluble in alcohol is albumen. 



The nerves are likewise of the same nature as the brain, but 

 they contain much less fatty matter and much more albumen. 

 They contain besides common fat, which separates from them 

 when treated with boiling alcohol. When the nerves are de- 

 prived as much as possible of their fatty matter by alcohol, they 

 become transparent When digested in that state in boiling water, 

 they do not dissolve but become white, opaque, and swell up ob- 

 viously in consequence of absorbing moisture. The residue of 

 nerve which has been treated with alcohol and water dissolves 

 almost completely in caustic potash. No ammonia is evolved 

 during the solution. The potash solution is precipitated in pur- 

 ple flocks by acids.* 



* Annals of Philosophy, i. 345. 

 4 



