176 RELATION OF VEGETABLE ALKALIES. 



quite certain, that a product of the vital process in a 

 plant, introduced into the blood, will, if its composition 

 be adapted to this purpose, supply the place of the first, 

 second, or third product of the alteration of the com- 

 pound of proteine. Indeed, it cannot be considered 

 merely accidental, that the composition of the most ac- 

 tive remedies, namely, the vegetable alkaloids, cannot 

 be shown to be related to that of any constituent of the 

 body, except only the substance of the nerves and brain. 

 All of these contain a certain quantity of nitrogen, and, 

 in regard to their composition, they are intermediate be- 

 tween the compounds of proteine and the fats. 



92. In contradistinction to the chemical character, 

 we find that the substance of the brain exhibits the char- 

 acters of an acid. It contains far more oxygen than 

 the organic bases or alkaloids. We observe, that quin- 

 ine and cinchonine, morphia and codeine, strychnia and 

 brucia, which are, respectively, so nearly alike in com- 

 position, if they do not produce absolutely the same 

 effect, yet resemble each other in their action more than 

 those which differ more widely in composition. We 

 find, that their energy of action diminishes, as the 

 amount of oxygen they contain increases (as in the case 

 of narcotine), and that, strictly speaking, no one of 

 them can be entirely replaced by another. There can- 

 not be a more decisive proof of the nature of their ac- 

 tion than this last fact ; it must stand in the closest rela- 

 tion to their composition. If these compounds, in point 

 of fact, are capable of taking a share in the formation or 

 in the alteration of the qualities of brain and nervous 



