430 VEDDER AND CLARK. 



Some claim that degeneration in the sciatic nerve in beriberi 

 begins in the most peripheral rami, in the smaller branches of 

 the lower part of the leg and foot, and proceeds centrally. These 

 observers claim that the large sciatic nerve shows degeneration 

 at a later period than its peripheral and smaller rami and that 

 at any given time the degeneration in a small peripheral ramus 

 is relatively greater and further advanced than in the fibers of 

 the sciatic in the upper thigh region and precedes any changes 

 in the nerve cells. Were these observations confirmed and proved 

 beyond doubt for polyneuritis in the fowl, the question of the 

 primary affection would be settled. On such a theory of periph- 

 eral neuritis we would not expect to find degenerative changes 

 in fiber tracts of the cord and the higher nerve centers. At 

 most, degenerative changes in the fiber tracts of the cord would 

 follow only after atrophic changes in the cells of the dorsal 

 root ganglia and of the ventral horn of gray matter had ad- 

 vanced to a considerable degree. Since, as Engelmann(9) has 

 shown, in a sectioned nerve "in the central stump, despite its 

 functional inactivity, no further changes (i. e., beyond the first 

 node of Ranvier) occurred for months," we should scarcely 

 expect to find degenerative changes in the fiber tracts of the cord 

 (aside from those fibers running between the nerve cells and 

 the periphery of the cord) during at least the first two months 

 of the experiment. This, however, does not agree with our 

 observations which show degenerative changes in the fiber tracts 

 of the cord and changes in its nerve cells. In view of the fact 

 that fowls die shortly after symptoms of neuritis manifest them- 

 selves, which circumstance occurs in most cases before the 

 thirtieth day of the experiment and rarely later than forty 

 days, it would seem that degeneration in the cord — on the 

 above hypothesis, a degeneration of disuse — would not be ex- 

 pected. We were not able to confirm the assumption, as will 

 be shown, that degeneration begins in and is more extensive 

 in the most peripheral fibers. 



Our microscopic study comprises : 



A. Pathology. 



1. Changes in the heart. 



2. Degenerative changes in the peripheral nerves including 



the vagus. 



3. Degenerative changes in the nerve roots. 



4. Changes within the fiber tracts of the cord and brain. 



5. Changes in the nerve cells of the cord and dorsal root 



ganglia. 



6. Regeneration. 



B. Time of onset of degeneration in peripheral nerves. 



