STUDY OF POLYNEURITIS GALLINARUM. 429 



In considering in this connection the general question of 

 polyneuritis, it is natural to inquire whether the neuritis is 

 peripheral or involves the entire nervous system. The neuritis 

 produced in fowls by a prolonged diet of polished rice is, so far 

 as the best evidence indicates, a neuritis due to a deficiency of 

 some food constituent or constituents necessary for the main- 

 tenance of the metabolic and functional activity of the nervous 

 system. The numerous feeding experiments noted above and 

 the experience and results of Eijkman, Fraser and Stanton, 

 Chamberlain and Vedder, and others well-nigh place this hy- 

 pothesis beyond the pale of doubt. This being granted, it is 

 probable that the neuritis is, in a greater or lesser degree, a 

 general systematic affection — greater or lesser, because one would 

 not expect different animals to react similarly to any given 

 etiological factor. 



The observation that some of our fowls show prostration with- 

 out showing any well-marked symptoms of peripheral neuritis is 

 evidence favoring the theory of a general nervous affection. 

 This prostration comes on suddenly. It is extremely difficult to 

 bring about recovery after the severest prostration. On the 

 other hand, fowls show varying degrees of peripheral neuritis 

 in the legs while maintaining otherwise good systemic conditions. 

 As many cases come under this latter class, and as the affection 

 often appears to be distinctly limited to the legs in these fowls, 

 we are justified in saying that, whatever the state of the general 

 nervous system, the disease shows a great tendency to involve 

 the peripheral nerves. However, certain observations on the 

 ganglia cells, the nerve cells of the lumbosacral cord, and the 

 anatomical changes in the fiber tracts of the cord and the brain 

 stem itself have convinced us that the central nervous system 

 is much more involved than has been generally thought. 



In those cases where the affection is selective enough to be 

 termed peripheral neuritis, one naturally inquires whether it is 

 a primary or a secondary affection ; that is, whether the degen- 

 eration of the fibers of the peripheral nerve precedes or follows 

 changes in the nerve cells of these fibers. From our present 

 knowledge of the degeneration of nerves, there is little difficulty 

 in supposing that the degeneration in the fibers may be primary, 

 secondary to, or simultaneous with, degenerative changes in their 

 nerve cell. For we know on the Wallerian theory that a fiber 

 severed from its cell or deprived of the "tropic" influence of the 

 cell undergoes degeneration. And, on the other hand, in a cell 

 thus separated from its nerve fiber, atrophic changes occur from 

 disuse. 



