NERVOUS SYSTEM IN GENERAL. 27 



a nerve globule to an element of another variety, or simply 

 to another nerve globule. 



These nerve fibres seem to be only a physiological sup- 

 plement to the globule from which they originate; every 

 excitation of the fibre is retained by the globule, arid vice 

 versa : the fibre disconnected from its globule undergoes a 

 degeneration (fatty) more or less complete. 



2. Life of the Nervous System. This physiological whole 

 (globule and its prolongations) lives and is nourished : the 

 nerve centres, composed practically of globules, need an 

 enormous quantity of material, and give back to the sur- 

 rounding media (by means of the blood) a large quantity of 

 refuse matter. The mass of nerve fibres (nerves) consumes 

 likewise some materials, and produces refuse matter ; they 

 in other words are fed; they are very vascular, and when 

 the supply of blood is shut off, phenomena resembling de- 

 composition may be observed. 



It will be noticed, farther on, that the materials consumed by 

 the muscles during their activity are principally hydro-carbons 

 (sugars and fats) and also albuminoids in small quantity. On the 

 other hand, the nerve element seems to require albuminoid sub- 

 stances; and the more intense the nerve work, the greater will be 

 the amount of refuse material, caused by combustion of the albu- 

 minoids (especially urea), in the excretions, in the urine, and in 

 the products of the liver. According to Biasson (1868) the amount 

 of urea excreted by man varies according to the amount of cerebral 

 activity. Again, Oscar Liebreich has shown that, in animals who 

 have been made to die by pain, after cutting the sensitive roots of 

 one side of the spinal cord, this side (reduced to inertia) would 

 consume less protagon than the other side. Protagon, whose com- 

 position is not yet defined, seems to be a compound of fatty phos- 

 phates and neurine, and serves for the nutrition of the nervous 

 system, to which it is carried by the blood globule. According to 

 Austin Flint, Jr., the excrementitial product formed by the dis- 

 assimilation of the brain and of the nerves, at the expense of prot- 

 agon, is represented by cholesterine, which is separated from the 

 blood by means of the liver, and then thrown into the intestines. 

 This view is based upon a number of experiments, which show, 

 moreover, that the excretion of cholesterine is in direct ratio to 

 the nervous activity. The common expression, "to feel bilious," 

 seems justified by one of the elements of the bile, viz., cholesterine. 



These acts of nutrition produce in the nerves a disengage- 

 ment of forces, which are brought to light by electrical 

 currents ; this phenomenon, though not directly observed in 

 the nerve globules, is very evident in the peripheral nerves. 



