584 NERVOUS SYSTEM. 



Regarding cholesteriiie as an excrementitious product, to be classed with principles 

 destined simply to be eliminated from the organism, the nerve-substance proper has been 

 found to contain the following proximate principles, the chemical properties of which 

 have been more or less accurately determined ; viz., protagon, neurine, fatty matters 

 combined with phosphorus, and bases combined with peculiar fatty acids. 



Protagon. This principle was discovered by Liebreich and was first described in 1865. 

 Its formula is CnaHauOaaiNUP. It may be extracted by the following process : The cere- 

 bral substance is bruised in a mortar and afterward shaken with water and ether in a 

 closed vessel. The mixture is then exposed to a temperature of 32 Fahr., and the 

 ethereal layer, containing cholesterine, is removed. The insoluble mass is then extracted 

 with alcohol (85 per cent.) at 113, is again filtered, and is exposed to a temperature of 

 32. An abundant precipitate then separates, which is washed with ether and desiccated 

 in vaciw. The protagon is thus obtained in the form of a white powder. Since this 

 principle has been described in the brain-substance, a compound analogous to if not 

 identical with protagon has been discovered by Hermann in the blood-corpuscles. In 

 its general and chemical characters, protagon resembles the albuminoid proximate prin- 

 ciples ; but it presents the remarkable difference, that the sulphur, which exists in many 

 of the principles of this class, is replaced by phosphorus. It is stated by Robin that pro- 

 tagon is not a true proximate principle but is simply impure or imperfectly-prepared 

 lecithene. 



Neurine. This name has been applied to a rather indefinite principle supposed to 

 represent the albuminoid element of the nervous tissue ; but its characters as a proximate 

 constituent of the nerve-substance have never been well determined. Robin and Verdeil 

 place neurine among the proximate principles of probable existence. According to these 

 authors, this is the organic substance of the brain, not soluble in alcohol. When inciner- 

 ated it does not leave a residue impregnated with phosphoric acid, like the cerebral fatty 

 matter. According to more recent investigations, particularly those of Liebreich, neurine 

 is a derivative of protagon. The neurine of Liebreich is obtained by boiling protagon 

 for twenty-four hours in baryta-water, when there are formed the phospho-glycerate of 

 baryta, and a new base, neurine. It is evident that this substance cannot properly be 

 regarded as a well-determined proximate principle. 



The observations of Wurtz upon the synthesis of neurine are important as a step tow- 

 ard the synthesis of organic nitrogenized principles, but they do not afford an example 

 of the actual formation of a characteristic nitrogenized constituent of the nerve-tissue. 

 They simply show that the chlorohydrate of an artificial organic compound presents crys- 

 tals identical with the chlorohydrate of neurine extracted from the brain. 



Cerebral Fatty Principles. Researches into the composition of the fatty principles 

 found in the nervous substance have been so indefinite and unsatisfactory in their results, 

 that, even now, they possess but little physiological interest. In the earlier observations, 

 the fats extracted from the nerve-tissue were generally combined with cholesterine. 

 This substance has now been isolated, and the residue contains a variety of principles, 

 which seem, under physiological conditions, to be intimately united with the nitrogen- 

 ized substance, presenting one of the exceptions to the general law that fats exist in the 

 body uncombined except with each other. In this mass of fatty matter, we can deter- 

 mine the presence of oleine, margarine, and stearine ; but these are combined with other 

 fats, fatty acids, etc., the remarkable peculiarity of most of which is, that they contain 

 a certain proportion of phosphorus. These peculiar principles have received a variety 

 of names, as they have been described more or less minutely by different observers, such 

 as cerebrine, white and red phosphorized fat, lecithene, cerebric acid, and cerebrate of 

 soda. The application of most of these names is very indefinite, and when we say that 



