CHEMICAL COMPOSITIOX OF XERYE. 153 



•u-hilst it may contain filjres sent by the s^nniiarhetic to the spinal nen-es or to the 

 spinal cord, must necessarily contain all those which yiroceed from the cord to the 

 sjnnpathetic. and that, on the otlier hand, the peripheral division must contain. 

 the filjres immediately proceeding from the s;5^npathetic and distributed peri- 

 pherally ^vith the spinal nerve. 



It seems on the whole reasonable to conclude that nerve-fibres take 

 their rise in the ganglia both of the cerebro-spinal and sjanpathetic 

 nerves, and are in both kinds of nerves mixed "with fibres of cerebral 

 or spinal origin ; that the ganglia are nervous centres which may pro- 

 bably receive through afferent fibres impressions of which we are uncon- 

 scious and reflect these impressioual stimuli upon efferent or motor 

 fibres: that perhaps, even, certain motorial stimuli emanate from them; 

 the movements excited by or through the ganglia being always invo- 

 luntary, and affecting chiefly the muscular parts of the viscera, the 

 sanguiferous, and perhajis the absorbent vessels ; and that, in fine, the 

 chief purpose served in the animal economy by the ganglia and the gan- 

 glionic nerve fibres, whether existing in acknowledged branches of the 

 sympathetic, or contained in other nerves, is to govern the involuntary, 

 and, for the most part,imperceptible movements of the vascular system, 

 as well as the secretory and nutritive processes, in so far at least as 

 these are not dependent on the brain and spinal cord, 



CHEMICAL COMPOSITION. 



The information we possess respecting the chemical composition of 

 nervous matter is for the most part founded on analyses of portions of 

 the brain and spinal cord ; but the substance contained in the nerves, 

 which is continuous with that of the brain and cord, and similar in 

 physical characters, appears also, as far as it has been examined, to be 

 of tlie same general chemical constitution. Xo very careful comparative 

 analysis has yet been made of the grey and white matter, to say nothing 

 of the different structural elements of the nervous substance ; and 

 indeed it must be remembered, that, in portions of brain subjected to 

 chemical examination, capillary blood-vessels, connective and perhaps 

 other accessory tissues, as well as interstitial fluid, are mixed up in 

 greater or less quantity with the true nervous matter, and must so far 

 affect the result. 



Like most of the other tissues of the Ijody the nervous substance 

 contains a large pro]wrtion of water (from three-fourths to four-fifths 

 of its weiglit). Of the residue which remains after the removal of this 

 by evaporation or other means the larger part consists of a phosphur- 

 reted fat, which may be obtained crystallized, and in this condition was 

 termed by 0. Liebreich protagon. The crystalline substance, however, 

 is in reality a mixture of two othei' substances — kcifhin and neiirin 

 (Hoppe-Seyler) — and doubtless includes the fatty acids which were 

 enumerated by Fremy and others : it appears mainly to compose the 

 medullary sheath of the nerves. 



Lecithin was first obtained from yelk of egg (by Gobley). It con- 

 tains nearly 4 per cent, of phosphorus, and has a very complex constitu- 

 tion. 



STeurin, sometimes termed cholin, is found also in the bile. It 

 possesses basic properties, and is, moreover, said to be one of the pro- 

 ducts of decomposition of lecithin. 



A substance named Cerebrin is also described as being frequently 



