ILLUSTRATIONS. 



Photomicrographs by Martin and Cortes. Camera lucida outlines were used in the preparation 



of all the drawings. 



Plate I. 



Fig. 1. Photomicrograph of a teased preparation of sciatic nerve from a 

 normal fowl. (Marchi method.) Zeiss 4X4 mm. 

 2. Transverse section of lateral fiber column of thoracic spinal cord 

 of normal fowl. (Marchi method.) At (a) blackened masses 

 are seen in close proximity to the fibers. At (6) the black 

 globules appear to be within the fiber. 



Plate II. 



Fig. 3. Photomicrograph of a teased preparation of the sciatic nerve of 

 fowl 6. (Marchi method.) For two days this fowl had been 

 unable to stand, but appeared to be in good condition otherwise. 

 Different stages of degeneration are here illustrated. Note oc- 

 casional globules of degenerated myelin in some fibers (a), a 

 diffuse blackening of the medullary sheath with indications of 

 segmentation in fiber (6), and large globules of degenerated 

 myelin in fiber (c). Zeiss 4X4 mm. 

 4. Fiber from sciatic nerve of fowl 6, showing advanced degeneration. 

 (Marchi method.) Note large globules and small droplets of 

 degenerated myelin and clear spaces between. The neurilemma 

 sheath is well shown. Zeiss 4X4 mm. 



Plate III. 



Fig. 5. Teased preparation of vagus of fowl 13 (good general condition, 

 but unable to walk since three days). (Marchi method.) This 

 figTire shows relatively advanced degeneration (for our series). 

 Numerous large globules of degenerated myelin are seen hero 

 and there. At the periphery where the individual fibers aro 

 best seen, globules are to be observed at frequent intervals in 

 every fiber. Zeiss 4 X AA. 

 6. High-power magnification of an area of the same preparation. 



Plate IV. 



Fig. 7. Drawing of a nerve fiber from the sciatic to show early stage of 

 myelin degeneration. (Marchi method.) Note diffuse blacken- 

 ing, tendency to segmentation (s), and beginning globular ar- 

 rangement of the myelin (G) ; (n) is nucleus of neurilemma 

 sheath. Zeiss 4X4 mm. Apochomatic (?). 

 8. From a transverse section of a sciatic nerve showing marked 

 degeneration, to illustrate the percentage of fibers showing vary- 

 ing degrees of degeneration in a given plane. . A majority of 

 the fibers show blackening to some extent, a, b, c, etc., are cross 

 sections of the larger globules of degenerated myelin. Zeiss 

 2x4 mm. Apochomatic. 



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