58 



ANIMAL CHEMISTRY. 



tables, intermediate in composition between 

 the fats and the compounds of proteiue, 

 may be applied in the organism to the same 

 purpose. 



91. According to the researches of Fremy, 

 the chief constituent of the fat found in the 

 brain is a compound of soda with a peculiar 

 acid, the cerebric acid, which contains, in 

 100 parts, 



Carbon 66-7 



Hydrogen 10'6 



Nitrogen 2'3 



Phosphorus 0*9 



Oxygen 19-5 



It is easy to see that the composition of 

 cerebric acid differs entirely, both from that 

 of ordinary fats and of the compounds of 

 proteine. Common fats contain no nitrogen, 

 while the compounds of proteine contain 

 nearly 17 per cent. Leaving the phos- 

 phorus out of view, the composition of this 

 acid approaches most nearly to that of 

 choleic acid, although these two compounds 

 are quite distinct. 



92. Brain and nervous matter is, at all 

 events, formed in a manner similar to that 

 in which bile is produced; either by the 

 separation of a highly nitrogenized com- 

 pound from the elements of blood, or by 

 the combination of a nitrogenized product 

 of the vital process with a non-azotized 

 compound (probably, a fatty body.) All 

 that has been said in the preceding pages 

 on the various possible ways by which the 

 bile might be supposed to be formed, all the 

 conclusions which we attained in regard 

 to the co-operation of azotized and non- 

 azotized elements of food, may be applied 

 with equal justice and ecjual probability to 

 the formation and production of the nervous 

 substance. 



We must not forget that, in whatever 

 light we may view the vital operations, the 

 production of nervous matter from blood 

 presupposes a change in the composition 

 and qualities of the constituents of blood. 

 That such a change occurs is as certain as 

 that the existence of the nervous matter 

 cannot be denied. In this sense, we must 

 assume, that from a compound of proteine 

 may be formed a first, second, third, &,c., 

 product before a certain number of its ele- 

 ments can become constituents of the nerv- 

 ous matter; and it must be considered as 

 quite certain, that a product of the vital pro- 

 cess in a plant, introduced into the blood, 

 will, if its composition be adapted to this 

 purpose, supply the place of the first, se- 

 cond, or third product of the alteration of 

 the compound of proieine. Indeed it can- 

 not be considered merely accidental, that 

 the composition of the most active remedies, 

 namely, the vegetable alkaloids, cannot be 

 shown to be related to that of any consti- 

 tuent of the body, except only the substance 

 of the nerves and brain. All of these con- 

 tain a certain quantity of nitrogen, and, in 

 regard to their composition, they are inter- 



| mediate between the compounds ot proteine 

 and the fats. 



93. In contradistinction to their chemical 

 character, we find that the substance of the 

 brain exhibits the characters of an acid. It 

 contains far more oxygen than the organic 

 basis or alkaloids. We observe, that qui- 

 nine an'd cinchonine, morphia and codeine, 

 strychnia and brucia, which are, respec- 

 tively, so nearly alike in composition, 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 speak- 

 ing, no one of them can be entirely replaced 

 by another. There cannot be a more de- 

 dsive proof of the nature of their action 

 than this last fact ; it must stand in the 

 closest relation to their composition. If 

 these compounds, in point of fact, are capa- 

 ble of taking a share in the formation or in 

 the alteration of the qualities of brain and 

 nervous matter, their action on the healthy 

 as well as the deceased organism admits of 

 a surprisingly simple explanation. If we 

 are not tempted to deny, that the chief con- 

 stituent of soup may be applied to a purpose 

 corresponding to its composition in the 

 human body, or that the organic constituent 

 of bones may be so employed in the body 

 of the dog, although that substance (gelan- 

 tine in both cases) is absolutely incapable 

 of yielding blood ; if, therefore, nitrogenized 

 compounds, totally different from the com- 

 pounds of proteine, may be employed for 

 purposes corresponding to their composi- 

 tion; we may thence conclude that a pro- 

 duct of vegetable life, also different from 

 proteine, but similar to a constituent of the 

 animal body, may be employed by the organ 

 ism in the same way and for the same pur- 

 pose as the natural product, originally 

 formed by the vital energy of the animal 

 organs, and that indeed from a vegetable 

 substance. 



The time is not long gone by, when we 

 had not the very slightest conception of the 

 cause of the various effects of opium, and 

 when the action of cinchona bark was 

 shrouded in incomprehensible obscurity. 

 Now that we know that these effects are 

 caused by crystallizable compounds, which 

 differ as much in composition as in their 

 action on the system ; now that we know 

 the substances to which the medicinal or 

 poisonous energy must be ascribed, it would 

 argue only want of sense to consider the 

 action of these substances inexplicable- ; and 

 to do so, as many have done, because they 

 act in very minute doses, is as unreasonable 

 as it would be to judge of the sharpness of 

 a razor by its weight. 



94. It would serve no purpose to give 

 these considerations a greater extension at 

 present. However hypothetical they may 

 appear, they only deserve attention in so far 



