STUDY OF POLYNEURITIS GALLINARUM. 449 



(b) A form in which there is pronounced neuritis, but the fowl 

 remains in good general health. These fowls will also recover 

 from the neuritis after several months' treatment with the ex- 

 tract of rice polishings. 



(c) A form described above as fulminating cases, in which the 

 symptoms of neuritis are absent, but in which greater general 

 prostration occurs. These fowls recover speedily when given 

 extract of rice polishings. 



2. In polyneuritis gallinarum developing after a prolonged 

 diet of polished rice the heart may show no microscopic change. 

 In other cases the heart may show slight oedema, a slight increase 

 in pigment, or an appearance of beginning mucoid or parenchym- 

 atous degeneration. 



3. While in marked cases of neuritis every fiber of the vagus 

 may and usually does show degenerative changes, as indicated 

 by the Marchi method, no fiber has been observed in which the 

 change was far advanced. We have not been able to correlate 

 the extent of degeneration in the vagus with the change in the 

 heart nor with the severity of the symptoms before death. 



4. No marked changes suggestive of degeneration have been 

 observed in the cervical sympathetic ganglia nor in the post- or 

 preganglionic fibers. 



5. In every one of the 56 fowls which had been fed thirty- 

 five days or more on polished rice, changes indicative of degen- 

 eration (Marchi method) were seen in the fibers of the sciatic 

 nerve, regardless of whether symptoms of neuritis had or had 

 not manifested themselves before death. (Plate II, fig. 3, and 

 Plate XI, fig. 24.) 



6. Advanced degeneration in the peripheral nerve fibers mani- 

 fests itself by a change in both myelin sheath and in the axis 

 cylinder. The myelin sheath breaks up into globules and drop- 

 lets, which stain black in the Marchi solution — indicative of 

 fatty degeneration. The axis cylinder breaks up into segments 

 or disintegrates in all those fibers showing advanced degeneration 

 in the medullary sheath. (Plate V, fig. 9.) 



7. The degree of degeneration in the sciatic nerve corresponds 

 closely with the extent of the paralysis of the legs. Advanced 

 degeneration was observed in only 10 to 15 per cent of the fibers 

 of the sciatic nerve of fowls showing pronounced symptoms of 

 leg paralysis. In the remaining fibers the change was not ad- 

 vanced. 



8. We could detect no difference in the degeneration in the 

 sciatic and its peripheral branches either as regards extent or 

 time of onset. 



