424 FUNCTIONS OF THE NERVES. [ch. hi. 



to maintain its continued existence by restoring^ the solid 

 and fluid particles worn away and dissipated by the movements 

 going on. It is necessary to the proper performance of this 

 function, that there be not only a due supply of food of a proper 

 quality, but also that those various viscera be healthy, which 

 carry on digestion, and by the combined function of which, the 

 food is converted into chyle, and rendered fit to be mixed with 

 the blood. Yet when this process is completed, nutrition is 

 not accomplished, but only the nutritive materials supplied to 

 the blood, from which the wasted portion of our body may 

 be restored; and the reparation of the lost material takes 

 place by some admirable arrangement, and by a power as yet 

 unknown, which knows how to restore to each portion of the 

 body its lost particles, to apply them, and cause them to 

 adhere. 



Many physiologists, both ancient and modern, have main- 

 tained that nutrition is carried on through the nerves. Thus 

 Sylvius, Willis, Glisson, and others, considered that there were 

 two fluids in the nerves, one thick and albuminous, subservient 

 to nutrition, the other very thin and spirituous, intimately 

 connected with the former, and subservient to sensation and 

 movement. The school of Boerhaave allowed one nervous fluid 

 only, and that most refined and active ; and held, not only that 

 sensation and motion were performed by this, but nutrition also 

 accomplished, when that fluid experienced the final elaboration 

 by which it was rendered similar to our organism. Haller 

 denied this nutritive property of the nervous fluid, because he 

 thought that our body must be nourished with a less spiritual 

 and more viscid fluid than the nervous fluid. ^ Marherr followed 

 Haller, and maintained the same doctrine.^ Tissot also adopted 

 it,* although in another place he attributes with Boerhaave a 



• This doctrine of attrition, and the destruction of the solid particles thence 

 arising, has been maintained by many distinguished persons, but too exclusively, 

 T think, as has been correctly shown by Kemme in his Essay entitled, ' Zweifel und 

 Errinnerungen wider die Lehre der Aerzte von der Ernahrung der festen Theile.' 

 Halle, 1778. This wearing away and loss of substance manifestly does not occur in 

 the nerves and brain, since the abrasion of so sensitive a substance could not occur 

 without pain, or, at least, without an unpleasant sensation. 



2 Elem. Phys,, tom. iv, p. 405. 



3 Prajlect. ad Boerh. Inst., torn. ii. 



< Yon Nerven, Iten Bandes, 2ter Theil, § 271. 



