72 ELBERT CLARK 



medullary sheath or axis cylinder. Indeed, Mott, Halliburton 

 and Edmonds ('04) in regeneration in nerves after section, find 

 that the new medullary sheath, as well as the axis cylinder, 

 progresses from the point of union of central and peripheral 

 stumps. I will suggest that the multiplication of the nuclei of 

 the neurilemma sheath and the formation of the embryonic nerve 

 fiber in the rice-fed fowls is comparable to the proliferation of 

 connective tissue in organs undergoing atrophy or degeneration 

 from other causes. In the fowls degeneration of the nerve fibers 

 is ;low and it is probable that the stimulus is not sufficient to 

 bring about a multiplication of the neurilemma nuclei until very 

 late. On the other hand, the trauma occasioned by transsection 

 of the nerve introduces a violent reaction and multiplication of 

 the nuclei of the neurilemma sheath rapidly ensues. 



INFILTRATION OF PHAGOCYTES AND ABSORPTION OF THE 

 DEGENERATED MYELIN 



Stroebe ('93), Mott, Halliburton and Edmonds ('04), Nageotte 

 ('11) and other have described an infiltration of phagocytic 

 wandering cells into medullated fibers undergoing myelin degen- 

 eration. Nageotte ('11) claims it as a constant occurrence and 

 sees in their presence a means of removal of the degenerated 

 myelin. According to Nageotte ('11), these foreign elements 



constitute the agents of greatest activity in the resorption of the de- 

 generated myelin. This does not signify that the syncytium of Schwann 

 remains inert; it can, indeed, resorb the myelin, and it is probable that, 

 in the fine fibers, it accomplishes the work of phagocyotosis of the 

 mylein without the aid of the foreign elements. In the large fibers, 

 at the end of the third day, one sees in the perinuclear protoplasmic 

 mass special granulations which result from the disintegration of the 

 myelin; but, in these fibers the larger part of the myelin becomes the 

 prey of the leucocytes. It is probable that the leucocytes emigrate 

 once their work is accomplished. 



In nerves of fowls with marked leg paralysis after about 30 

 days on polished rice, I have sometimes seen fibers in degener- 

 ation in which the appearance of infiltration by wandering cells 

 is very striking. These cells were all very small and, after Miiller 

 fixation, scarcely anything but the nucleus was to be seen in 



