214 
THOMPSON YATES LABORATORIES REPORT 
III. ON THE ULTIMATE FATE OF NERVE CELLS WHICH HAVE UNDER- 
GONE STRUCTURAL ALTERATION {a) AFTER SECTION OF THEIR 
AXONS, {h) AFTER CUTTING OFF OF THE AFFERENT IMPULSES 
IMPINGING UPON THEM 
{a) In one of his earlier papers Nissl* states that after section of the facial nerve the cells 
of the nucleus in the medulla gradually return to their normal appearance, ' probably because of 
the formation of new connections.' Since the appearance of this communication Marinesco and 
Van Gehuchten have published many papers on the question of the repair of the nerve cells. 
Both these observers have studied the change in the hypoglossal nucleus, and agree that if the cut 
ends of the sectioned nerve become united total repair is the rule, so that after the lapse of about 
100 days tlie two nuclei of the hypoglossal nerve are indistinguishable from each other. 
MARiNEscOjt however, regards the regeneration of the cut nerve as necessary ; thus he says : — 
' La regenerescence des nerfs peripheriques est done la fonction de la reparation cellulaire, 
et celli-ci depend de la premiere.' 
Van Gehuchten,! however, and in this he is supported by Nissl,§ states that he does not 
know of any evidence to show that suture makes any diflPerence at all in the rate of repair, though 
it may influence the nutrition of the cells in such a way that ultimately gradual atrophy takes 
place. He states that 14 months after enucleation of the eye in a rabbit he has found 
complete atrophy of the oculo-motor nucleus. 
Both II these writers describe in detail the series of changes which take place in a nerve 
cell on its way to resume the normal state, and though there are some minor diflferences in their 
description the general features observed are the same, viz., the cells gradually increase in volume 
up to about the lOOth day, whilst the Nissl granules become denser and more pressed together, 
causing the cell to have the appearance described as the pycnomorphic state. Later they slowly 
diminish in size, and ultimately become indistinguishable from the normal. 
In my former communication {/oc. c'lt.) I showed that after section of an anterior root of 
the cord the cells on that side in the ventral horn underwent obvious changes in from 10 to 
14 days. 
I have now observed the condition of the cord after a much longer period of time has 
elapsed. 
Exp. I. Cat. Vlth anterior post-thoracic root divided. Animal allowed to live \o dajs. 
The distal piece of the nerve was found to have undergone complete Wallerian degeneration. 
Sections were cut 10, 6, 3, and 2^ in thicicness. The cells showed distinct alteration, though not so 
marked as the condition which occurred at an earlier period. 
There was no increase in volume noticeable. The blue stain was more diffused, and the chromo- 
phylic granules had a powdery appearance. The nucleus was generally situated centrally, and its contour 
in some cells had a rosette shape ; it was occasionally, though rarel}', peripheral. The cells did not exhibit 
the pycnomorphic appearance. 
* Nissl. ' CenU'alb. fiir Nervenheilk. unci Psychiatric,' July, § Nissl. ' Miinch. metl. Woch.,' 1898, p. 6. 
1894. II IVIarinesco. 'Neurol. Centralb.,' 1898, p. 882. 
t Marinesco. 'La Presse Meilicale,' Oct. 5th, 1898, p. 202. V. Gehuchten. ' L'anatomie fine de la 
I Van Gehuchten. 'La Presse Medicale,' Jan. 4th, 1899. cellule nerveuse,' 1897. 
