The principles which he extracts from the brain by this method, are-1. a white sub stance called cerebric acid ; 2. cholesterine ; 3. a peculiar fatty acid called oleophosphorie ; 4. traces of elaine, margarine, and fatty acids. These principles are not always found in an isolated state ; for the cerebric acid is often combined with soda or phosphate of lime; arid the oleophosphoric acid is commonly found in the state of a salt of soda.
Cerebric acid, when purified, is white, and is in the form of crystalline grains. It dissolves without residue in boiling alcohol, is almost insoluble in cold ether, more soluble in boiling ether. It has the remarkable property of swel ling up, like starch, in boiling water, but ap pears to be insoluble in that liquid. It enters into fusion at a high temperature, approaching closely that at which it is decomposed, and is combustible. It contains no sulphur, but some phosphorus. The result of its a»alysis by Fremy is 66.7 per cent. of carbon, 10.6 of hydiogen, 2.3 of nitrogen, 0.9 of phosphorus, 19.5 of oxygen.
Oleaphosphorie acid is separated from cere bric acid by its solubility in ether. It is still accompanied by elaine and cholesterine, which are withdrawn from it by alcohol and ether. This acid is of a viscid consistence, insoluble in cold alcohol, but dissolving readily in boil ing alcohol ; it is insoiuble in ether. Placed in contact with soda, potass, and ammonia, it immediately gives soapy compounds. It forms compounds insoluble in water with other bases. M. Fremy has observed a remarkable transformation of oleo-phosphoric acid. When boiled for a long time in water or alcohol, it gradnally loses its viscidity and becomes a fluid oil, which is pure elaine, while the liquor con tains phosphoric acid. This decomposition be comes very rapid, when the liquor is rendered slightly acid. Although 111. Fremy's attempts to fonn this acid directly, by uniting elaine and phosphoric acid, were unsuccessful, he still deems it probable that this acid may consist of the elements in question and be analogous to the compound of sulphuric acid and elaine, or sulph-oleic acid. It contains from 1.9 to 2 per cent. of phosphorus in the condition of phos phoric acid.
111. Fremy also finds, as Couerbe had previ ously done, that cholestcrine may be extracted from the brain in considerable quantity. Ile
obtains it by boiling the ethereal product in alcohol rendered strongly alkaline by potass. A cerebrate, an olKite, and a phosphate of pot ass are thus obtained, with glycerine and cho lesterine. On cooling, the alcohol deposits the cerebrate and phosphate of potass and the cho lesterine; and in treating the deposit by cold ether, we remove all the cholesterine, which may be purified by subsequent crystallizations.
In preparations of the brain, preserved in spirits, a substance of crystalline character, which resembles cholesterine, is apt to form round the piece.
The quantity of phosphorus varies conside rably in different periods of life, and is greatly diminished in idiotcy. The following table from some analyses of L'Ileritie will illustrate this statement.
From theie comparative analyses it appears that the minimum of phosphorus exists in in fancy, in idiotcy, and in old age; and that the maximum of water is found in the infant. This latter fact is of practical interest, and affords some explanation of the greater tendency to liquid effusions in early childhood than in more advanced life.
Nervous actions.—In order to offer a clear explanation of the working of the nervous sys tem, it will not be amiss to quote a few ex amples of actions effected through its instru mentality.
Let me, however, first remark, that as the mind is connected more especially with the nervous system, so that system becomes the channel of its mandates, as well as of impres sions conveyed to it. But there can be no doubt that the nervous system can act inde pendently of the mind, and that certain actions which need the intervention of nerves and ner vous centres, are accomplished without the consciousness of the individual, and some tinzes in spite of his Will.
It seems, therefore, a correct, as it is cer tainly a convenient arrangement of nervous acts, to divide them into those in which the mind is concerned, either as an agent or as a recipient, ( mental nervous acts,) and into those which result from mere modifications in the nervous matter, quite independent of mental interference (physicol nervous acts).