436 VEDDER AND CLARK. 



globules must remain more or less a matter of speculation. 

 Our observations lead us to believe that they occur somewhere 

 near the same time. 



Certain nerve fibers observed by us from nerves showing 

 marked myelin degeneration gave indications of a segmentation 

 of the myelin sheath and a disappearance of myelin with a 

 persistence of the axis cylinder. This, however, has not been 

 sufficiently confirmed to claim it as a possible type of degeneration 

 in polyneuritis. 



The neurilemma. — The neurilemma persists throughout all 

 degenerative stages and in all fibers. No fiber was seen in 

 which the neurilemma could not be easily distinguished. In 

 Plate II, fig. 4, showing well-marked degeneration in a fiber 

 of the sciatic nerve, the typical appearance of the neurilemma 

 is well illustrated. Here the sheath of Schwann does not appear 

 hypertrophied nor is there present an increase in the number 

 of nuclei. " 



Degeneration in the 'proximal part of the sciatic and in its 

 peripheral rami. — All phases of the degeneration described above 

 for the fibers of the sciatic were to be seen in its peripheral 

 branches and no additional type was seen. On the theory that 

 the affection begins in the peripheral branches and progresses 

 toward the spinal cord, one would expect to find in preparations 

 from a given fowl more advanced and more extensive degenera- 

 tion in the peripheral rami than near the spinal cord. Further, 

 that degeneration might be found in the peripheral nerves — 

 those supplying the foot and lower part of the leg — and not 

 be apparent in the sciatic. Our observations do not warrant 

 either assumption. In two teased preparations from a given 

 nerve stained by the Marchi method, it is impossible to distin- 

 guish which is peripheral and which central. In both cases all 

 fibers show some degeneration. As stated above, in prepara- 

 tions from fowls presenting well-marked symptoms of peripheral 

 neuritis, 10 to 15 per cent of the fibers show well-marked degen- 

 eration. These are clearly differentiated from the remainder 

 of the fibers. The number of these fibers showing marked degen- 

 eration has always been found practically the same near the 

 cord and in the peripheral branches; thus in fowl 37, suffering 

 from marked peripheral neuritis, in 500 fibers from different 

 portions of the central end of the sciatic, 51, or 10.2 per cent, 

 showed well-marked degeneration. One of the finer peripheral 

 rami taken from near the foot contained 535 fibers of which 

 58, or 10.8 per cent, showed marked degeneration. 



