1. The degeneration of peripheral nerve fibres in polyneuritis is not identical with Wallerian degeneration.2. Symptoms of polyneuritis gallinarum were observed to correspond in time and rate of onset with changes in the neuraxon, being independent of the condition of the myelin sheath.To the memory of Dr Sutherland Simpson is due a word of appreciation. Not only did he suggest the present investigation, but through instruction in his “clinics of physiology,” as we may term them—his never boresome lectures—it has been the privilege of the writer, along with many others, to be inspired to the desire to help chart the hitherto unknown regions of life.