1910-11.] Independence of Peripheral Sensory Neurons. 
351 
Exp. ix. 3 weeks. Ganglion cells much shrunken, pale or densely 
staining. Granules dust-like. Outer neurons normal. 
Exp. x. 6 weeks. Ganglion cells much shrivelled, the nucleus often 
alone remaining. Occasionally dust-like granules are seen, 
but the staining is mostly diffuse. Outer neurons normal. 
Exp. xi. 15 weeks. Ganglion cells very much shrivelled, and diffusely 
stained. Outer neurons normal. 
Exp. xii. 16 J weeks. Ganglion cells mostly atrophic. Outer neurons 
practically normal. 
Exp. xiii. 38 weeks. Ganglion cells completely atrophic. Outer 
neurons practically normal. 
Discussion of Results . — Many more experiments were performed, but 
were rejected on account of complications, e.g. haemorrhage, injury to the 
ciliary nerves, etc. The thirteen cases given above may be taken as uncom- 
plicated examples of the effect of section of the optic nerve upon the retina. 
These results show that as early as 48 hours after operation slight 
degenerative changes have appeared in the ganglion cells. The degenera- 
tion, however, does not proceed very rapidly, no pronounced change being 
observed before the lapse of 3 weeks. At 15 weeks the changes in the 
ganglion cells are very marked, and at 38 weeks atrophy is complete. The 
outer neurons, on the other hand, remain practically unchanged throughout. 
The question of inherent stability on the part of the outer neurons 
had to be considered, and a series of autolytic experiments was carried 
out. Fresh eyeballs from the ox, cat, dog, and rabbit were dipped in melted 
paraffin (in order to seal from the atmosphere and obviate putrefactive 
conditions) and left for varying lengths of time. On histological examina- 
tion it was found that the outer neurons, far from exhibiting any marked 
power of resistance to autolysis, were of all the retinal elements the most 
perishable. The ganglion cells, on the other hand, were comparatively well 
preserved, even after a considerable lapse of time. 
The conclusion is arrived at that the changes, which in the case of the 
ganglion cells after section of the optic nerve were so pronounced, were 
degenerative and the result of the abnormal anatomical conditions. The 
preservation of the easily perishable outer neurons indicated that these 
latter elements are unaffected by such conditions ; in other words, that the 
peripheral sensory neuron of the retina is anatomically an independent 
organism. 
( Issued separately April 12 , 1911 .) 
