7th. The alkalies have an effect upon the cerebral substance precisely opposite to that of the acids. They make it fluid, and even dissolve it completely after a short time. I have observed, with regard to this, that the grey substance is much quicker altered by them than the white, which is softened, disappears in part, but still leaves a considerable portion that is not dissolved. From whatever part we take these two substances to submit them to the action of the alkalies, the result is the same. The alkalies act also evidently upon the medullary substance of the nerves. This action, as I have said, has been of great assistance to Reil in his experiments.
8th. Thouret and Fourcroy have discovered, that the brain, after being buried, lessens considerably in size, and changes to a brittle substance, capable of softening under the finger, miscible in water, exhaling a disagreeable odour, having the properties of ammoniacal soap, and resembling very closely spermaceti in its nature. Do the nerves undergo a similar alteration in their medullary substance? We know nothing at present by which we can determine this question.
9th. The muriate of soda, when sprinkled upon slices of the brain and the pulpy nerves, increases their consistence.
10th. The digestive juices generally alter with ease the medullary substance of the brain. I think, however, that they would have a much more powerful action upon it in a natural than a boiled state; for all the re-agents are in general more powerful in the first of these states. We know that most carnivorous animals esteem the cerebral substance delicious food. Those that feed upon birds, the parietes of whose craniums are easily broken, almost always eat the brain first. The weasel, the polecat, &c. furnish examples of this. Man considers the brain as one of the most dainty parts of the animal. The nerves are much less easily digested; but this depends wholly upon their coat, which does not yield so readily to boiling as the other parts. For example, the tendons, which are as hard or harder than the nerves in a natural state, become much softer by boiling. We can distinguish in boiled meat each of these parts. The first, in its gelatinous state, is more pleasant and digestible.