The problem of the amount of independence possessed by the units which go to make up the nervous system is one which has long occupied the attention of neuro-pathologists, and is still far from solved. That degenerative changes, as the result of peripheral injury, may extend across several intermediate neurons is indicated by the work of many investigators, notably v. Monakow, Campbell, Bolton, etc. Thus after enucleation of the eyeball changes have been met with in the visual cortex, showing that degeneration has travelled over the neurons situated at the basal ganglia of the cerebrum to the neurons in the visual cortex itself. Interruption of the sensory conduction path affects the integrity of themore centrally placed neurons. The question of the stability of the peripheral neurons under similar conditions has not received attention. Birch-Hirschfeld in 1900 published the results of a large series of experiments upon the retina, including a few cases of the effects of experimental section of the optic nerve.