444 VEDDER AND CLARK. 



of apparently empty space. This appearance is strongly sugges- 

 tive of a partial absorption of the large globules of degenerated 

 myelin seen in the nerves of fowls with marked peripheral 

 neuritis. These observations make it probable that regeneration 

 in those nerves showing advanced degeneration is very slow or 

 doubtful, that recovery after neuritis means a recovery of those 

 nerve fibers which do not show advanced degenerative processes, 

 and that in recovery after peripheral neuritis the fowl is able 

 to do without the 10 or 15 per cent of the fibers which are 

 the slowest to regenerate. Rapid regeneration after prostration 

 alone confirms the anatomical findings that degeneration is fur- 

 ther advanced in the nerves of those fowls showing symptoms 

 of peripheral neuritis than prostration without peripheral 

 neuritis. 



III. OBSERVATIONS ON THE EARLIEST DEGENERATIVE CHANGES IN 



THE NERVES. 



Time of onset of degenerative changes in the fibers of the 

 sciatic nerve. — Finding that degenerative changes were to be 

 observed in the sciatic nerve of all those fowls which had been 

 on a polished rice diet for thirty-five days or more, even though 

 symptoms of neuritis did not manifest themselves (Plate XI, 

 fig. 24), we sought to determine when the first changes are to 

 be detected. From the advanced degeneration occurring in 

 some fibers of such nerves, it became evident that degenerative 

 changes took place long before signs of neuritis were evident. 

 It became an interesting point to determine at what period these 

 degenerative changes are first to be detected. Accordingly 12 

 fowls were fed polished rice and killed at varying intervals of 

 time, ranging from seven to twenty-three days. Thus Nos. 24 

 and 25 were killed after seven days on polished rice; Nos. 26 

 and 27, after eleven days ; Nos. 28 and 29, after fourteen days ; 

 No. 30, after sixteen days ; No. 31, after seventeen days ; No. 32, 

 after eighteen days; No. 33, after nineteen days; No. 35, after 

 twenty-two, and No. 36, after twenty-three days on polished rice. 

 None of these fowls showed symptoms of peripheral neuritis 

 and, with the exception of Nos. 35 and 36 (somewhat droopy), 

 all were lively and apparently normal. As controls 4 normal 

 fowls were used. The mitochondria methods proved to be the 

 most delicate and serviceable in this series, and the methods 

 of Benda, Meves, Bensley, and Regaud were employed as checks 

 on each other. It was found that after prolonged fixation in 

 Miiller's fluid (two weeks or more in 2 or 3 changes), each 

 of the above methods gave excellent results. As the iron- 



