ALKALIES ON THE NERVOUS SYSTEM. 183 



these compounds, by means of their elements, take 

 a share in the formation of new, or the transforma- 

 tion of existing brain and nervous matter. 



However strange the idea may, at first sight, ap- 

 pear, that the alkaloids of opium or of cinchona 

 bark, the elements of codeine, morphia, quinine, 

 &c., may be converted into constituents of brain 

 and nervous matter, into organs of vital energy, 

 from which the organic motions of the body derive 

 their origin ; that these substances form a consti- 

 tuent of that matter, by the removal of which the 

 seat of intellectual life, of sensation, and of con- 

 sciousness, is annihilated: it is, nevertheless, cer- 

 tain, that all these forms of power and activity are 

 most closely dependant, not only on the existence, 

 but also on a certain quality of the substance of the 

 brain, spinal marrow, and nerves; insomuch, that 

 all the manifestations of the life or vital energy of 

 these modifications of nervous matter, which are 

 recognized as the phenomena of motion, sensation, 

 or feeling, assume another form as soon as their 

 composition is altered. The animal organism has 

 produced the brain and nerves out of compounds 

 furnished to it by vegetables ; it is the constituents 

 of the food of the animal, which, in consequence 

 of a series of changes, have assumed the properties 

 and the structure which we find in the brain and 

 nerves. 



90. If it must be admitted as an undeniable 

 truth, that the substance of the brain and nerves is 



